Operational modes for closed-loop neuromodulation systems

Abstract

A medical device includes one or more memories; and processing circuitry coupled to the one or more memories, wherein the processing circuitry is configured to: determine a stimulation intensity at which the medical device is delivering electrical stimulation; based on the stimulation intensity, select an operation mode as one of a dual threshold mode or a single threshold mode, wherein in the dual threshold mode, the medical device determines adjustment to delivery of electrical stimulation based on characteristics of a first sensed bioelectric signal being outside an upper threshold and a lower threshold of the dual threshold mode, and wherein in the single threshold mode, the medical device determines adjustment to delivery of the electrical stimulation based on characteristics of a second sensed bioelectric signal being greater than or less than a single bioelectric signal threshold; and cause the medical device to operate in the selected operation mode.

Description

Docket No.: A0013938W001 OPERATIONAL MODES FOR CLOSED-LOOP NEUROMODULATION SYSTEMSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 765,087 filed February 28, 2025, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] This disclosure generally relates to medical devices and, more particularly, electrical stimulation therapy.BACKGROUND

[0003] Medical devices may be external or implanted and may be used to deliver electrical stimulation therapy to various tissue sites of a patient to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson’s disease, other movement disorders, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, or gastroparesis. A medical device may deliver electrical stimulation therapy via one or more leads that include electrodes located proximate to target locations associated with the brain, the spinal cord, pelvic nerves, peripheral nerves, or the gastrointestinal tract of a patient. Hence, electrical stimulation may be used in different therapeutic applications, such as deep brain stimulation (DBS), spinal cord stimulation (SCS), pelvic stimulation, gastric stimulation, or peripheral nerve field stimulation (PNFS).SUMMARY

[0004] In general, the disclosure describes devices, systems, and techniques for automatic adjustment of a closed-loop feedback policy for example closed-loop operational modes with limited user interaction, as well as examples of automatic transition between different closed-loop operational modes. In the context of neuromodulation therapy, such as deep brain stimulation (DBS), closed -loop therapy refers to a medical device receiving a sensed bioelectric signal (e.g., a local field potential) signal, and controlling delivery of electrical stimulation based on the sensed bioelectric signal.

[0005] Examples of the closed-loop operations modes includes dual threshold (DT) mode, in which the closed-loop feedback policy defines a homeostatic window that includes an upper threshold and a lower threshold, and single threshold (ST) mode, in which the closed-loop feedback policy defines a single bioelectric signal threshold. In one or more examples, with limited to no user interaction, the medical device may automatically adjust the homeostatic window or adjust the single bioelectric signal threshold to achieve a desired modification to theDocket No.: A0013938W001 closed-loop feedback policy. Furthermore, in one or more examples, the medical device may be configured to automatically switch between the different operational modes (e.g., between DT and ST mode) with limited to no user interaction. In this manner, the example techniques may improve the technology of therapy delivery by automating changes to the closed-loop feedback policy or changes in operation modes with limited to no user interaction.

[0006] In one example, the disclosure describes a medical device comprises one or more memories; and processing circuitry coupled to the one or more memories, wherein the processing circuitry is configured to: determine a stimulation intensity at which the medical device is delivering electrical stimulation; based on the stimulation intensity, select an operation mode as one of a dual threshold mode or a single threshold mode, wherein in the dual threshold mode, the medical device determines adjustment to delivery of electrical stimulation based on characteristics of a first sensed bioelectric signal being outside an upper threshold and a lower threshold of the dual threshold mode, and wherein in the single threshold mode, the medical device determines adjustment to delivery of the electrical stimulation based on characteristics of a second sensed bioelectric signal being greater than or less than a single bioelectric signal threshold; and cause the medical device to operate in the selected operation mode.

[0007] In one example, the disclosure describes a method for delivery of electrical stimulation, the method comprising: determining, with processing circuitry of a medical device, a stimulation intensity at which the medical device is delivering electrical stimulation; based on the stimulation intensity, selecting, with the processing circuitry, an operation mode as one of a dual threshold mode or a single threshold mode, wherein in the dual threshold mode, the medical device determines adjustment to delivery of electrical stimulation based on characteristics of a first sensed bioelectric signal being outside an upper threshold and a lower threshold of the dual threshold mode, and wherein in the single threshold mode, the medical device determines adjustment to delivery of the electrical stimulation based on characteristics of a second sensed bioelectric signal being greater than or less than a single bioelectric signal threshold; and causing, with the processing circuitry, the medical device to operate in the selected operation mode.

[0008] The details of one or more examples of the techniques of this disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. l is a conceptual diagram illustrating an example system that includes an implantable medical device (IMD) configured to deliver DBS to a patient according to an example of the techniques of the disclosure.Docket No.: A0013938W001

[0010] FIG. 2 is a block diagram of the example IMD of FIG. 1 for delivering DBS therapy according to an example of the techniques of the disclosure.

[0011] FIG. 3 is a block diagram of the external programmer of FIG. 1 for controlling delivery of DBS therapy according to an example of the techniques of the disclosure.

[0012] FIG. 4 is a flow diagram illustrating example techniques of automatically adjusting a closed-loop feedback policy for a dual threshold operational mode.

[0013] FIGS. 5A-5E are conceptual diagrams illustrating examples of adjusting a center target of the homeostatic window or a homeostatic window range of the homeostatic window to generate an adjusted homeostatic window of the closed-loop feedback policy for the dual threshold operational mode.

[0014] FIG. 6 is a flow diagram illustrating example techniques of automatically adjusting a closed-loop feedback policy for a single threshold operational mode.

[0015] FIG. 7A is a conceptual diagram illustrating an example of an averaged bioelectric signal with a bioelectric signal threshold.

[0016] FIG. 7B is a conceptual diagram illustrating an example of an average intensity of electrical stimulation delivered over a period of time and average intensity thresholds.

[0017] FIG. 7C is a conceptual diagram illustrating an example of a bioelectric signal.

[0018] FIG. 7D is a conceptual diagram illustrating an example of changes to electrical stimulation intensity.

[0019] FIG. 8 is a conceptual diagram illustrating example of changing intensity levels for single threshold operational mode.

[0020] FIG. 9 is a flow diagram illustrating example techniques of selecting between operational modes.

[0021] FIG. 10 is a conceptual diagram illustrating example of stimulation intensity for selecting between operation modes.

[0022] FIG. 11 is a flowchart illustrating an example method of operation for adjusting a closed-loop feedback policy for a dual threshold operational mode.

[0023] FIG. 12 is a flowchart illustrating an example method of operation for adjusting a closed-loop feedback policy for a single threshold operational mode.

[0024] FIG. 13 is a flowchart illustrating an example method of selecting an operational mode.DETAILED DESCRIPTION

[0025] This disclosure describes example devices, systems, and techniques for automatically adjusting a closed-loop feedback policy for examples of operational modes, as well asDocket No.: A0013938W001 automatically selecting between operational modes. For purposes of illustration, the example techniques are described with respect to deep brain stimulation (DBS), such as automated DBS (aDBS), but the example techniques should not be considered limited to DBS or aDBS.

[0026] A patient may suffer from one or more symptoms treatable by electrical stimulation therapy. For example, a patient may suffer from brain disorder such as Parkinson’s disease, Alzheimer’s disease, or another type of movement disorder. DBS may be an effective treatment to reduce the symptoms associated with such disorders. In some example DBS therapies, a medical device (e.g., implantable medical device (IMD)) may be configured to deliver a set electrical stimulation (e.g., a set intensity).

[0027] While standard DBS therapies may address patient symptoms, with aDBS, the medical device receives as input sensed bioelectric signals, and the medical device controls the electrical stimulation (e.g., adjusts the delivery of electrical stimulation) based on the sensed bioelectric signals. In this manner, aDBS therapies form a closed-loop feedback, where the sensed bioelectric signals are used as feedback to control electrical stimulation. One example of the sensed bioelectric signal is a local field potential (LFP) signal, but other examples are possible, and generally include intrinsic or evoked bioelectric signals. A bioelectric signal may be a signal generated within and by the body (e.g., brain) of the patient.

[0028] A closed-loop feedback policy for an aDBS therapy may include example criteria used to determine whether, by how much, and / or how quickly to adjust the electrical stimulation. For instance, there are different example operational modes for aDBS therapy, such as a dual threshold (DT) mode or a single threshold (ST) mode. In DT mode, the closed-loop feedback policy may define a homeostatic window for the sensed bioelectric signal. The homeostatic window includes an upper threshold and a lower threshold. If a characteristic of the sensed bioelectric signal is greater than the upper threshold or less than the lower threshold, the medical device may adjust the delivery of the electrical stimulation. In ST mode, the closed-loop feedback policy may define a single bioelectric signal threshold. If a characteristic of the sensed bioelectric signal is greater than or less than the bioelectric signal threshold, the medical device may adjust the delivery of the electrical stimulation.

[0029] In addition to having different number of thresholds (e.g., two thresholds for DT mode and one threshold for ST mode), the DT mode and the ST mode may operate at different sampling rates. For example, in DT mode, the sensed bioelectric signal may be sampled at a relatively lower sampling rate (e.g., 1-50 Hz, such as approximately 5 Hz or below), and in ST mode, the sensed bioelectric signal may be sampled at a higher rate than in DT mode (e.g., 1-50 Hz, such as approximately 20 Hz or below). The sampling rate for ST mode may be greater than the sampling rate for DT mode.Docket No.: A0013938W001

[0030] While closed-loop therapy in DT mode or ST mode automatically adjusts parameters of the electrical stimulation (e.g., amplitude, pulse width, and / or frequency), a user (e.g., clinician, caregiver, or the patient) may desire to change the closed-loop feedback policy for more effective therapy. Changes to the closed-loop feedback policy may include changes to the homeostatic window for DT or changes to the single bioelectric signal threshold for ST to achieve a desired therapy goal.

[0031] In some examples, if the amplitude of the bioelectric signal is higher than a threshold (e.g., upper threshold for DT or single bioelectric signal threshold for ST), than the medical device may increase the stimulation intensity of the electrical stimulation (e.g., increase amplitude). If the amplitude of the bioelectric signal is less than a threshold (e.g., lower threshold for DT or single bioelectric signal threshold for ST), than the medical device may decrease the stimulation intensity of the electrical stimulation (e.g., decrease amplitude).

[0032] As an example, a clinician may determine that a patient benefits with delivery of higher intensity electrical stimulation more often than delivery of lower intensity electrical stimulation. In this case, there may be benefit in lowering the homeostatic window (e.g., the upper and lower thresholds) closer to a lower limit for DT or lowering the bioelectric signal threshold for ST so that medical device is biased towards delivering higher stimulation intensity. Stated another way, for DT mode, assume the upper threshold of the homeostatic window is at a first level. If the upper threshold of the homeostatic window is lowered from the first level to a second level, then there is a higher chance that the amplitude of the bioelectric signal will be greater than the upper threshold when the upper threshold is at the second level as compared to the first level. The same applies for ST mode, but with a single bioelectric signal threshold.

[0033] As another example, a clinician may determine that a patient benefits with delivery of lower intensity electrical stimulation more often than delivery of higher intensity electrical stimulation. In this case, there may be benefit in raising the homeostatic window (e.g., the upper and lower thresholds) closer to an upper limit for DT mode or raising the bioelectric signal threshold for ST mode so that medical device is biased towards delivering lower stimulation intensity. Stated another way, for DT mode, assume the lower threshold of the homeostatic window is at a first level. If the lower threshold of the homeostatic window is increased from the first level to a second level, then there is a higher chance that the amplitude of the bioelectric signal will be less than the lower threshold when the lower threshold is at the second level as compared to the first level. The same applies for ST mode, but with a single bioelectric signal threshold.

[0034] As yet another example, for DT mode, a clinician may determine that a patient benefits with adjustments to delivery of electrical stimulation in response to small changes in theDocket No.: A0013938W001 sensed bioelectric signal. In such examples, there may be benefit in narrowing the range of the homeostatic window (e.g., bring the upper threshold and lower threshold closer together to make a thinner homeostatic window). In some cases, for DT mode, a clinician may determine that a patient benefits with adjustments to delivery of electrical stimulation in response to large changes in the sensed bioelectric signal. In such examples, there may be benefit in widening the range of the homeostatic window (e.g., move the upper threshold and lower threshold further apart to make a wider homeostatic window).

[0035] Users may consider it challenging to manually control each of the parameters of the closed-loop feedback policy. That is, the user may find it cumbersome to define the upper and lower thresholds for DT mode or the bioelectric signal threshold for ST mode to achieve desired therapy goals. The user may also make errors in manually controlling each of the parameters of the closed-loop feedback policy to achieve a desired therapy goal. For instance, the user may increase the upper threshold for DT mode when the user should have decreased the upper threshold for DT mode.

[0036] With the example techniques described in this disclosure, manual control of parameters of the closed-loop feedback policy may not necessarily be available to a user, although manual control is possible. The user may be presented with options that indicate a generalized end-goal for the electrical stimulation (e.g., deliver higher intensity electrical stimulation more often), and the medical device may automatically adjust the closed-loop feedback policy based on user input.

[0037] For example, the medical device may receive a request to adjust a closed-loop feedback policy. The request itself may not define any of parameters of the closed-loop feedback, but may instead generalized therapy goals.

[0038] As an example, for DT mode, the closed-loop feedback policy may define a homeostatic window for a bioelectric signal. The request to adjust the closed-loop feedback policy may not define the upper or lower thresholds, or a center target for the homeostatic window, and may not define a range for the homeostatic window. In this example, the request may include at least one of a treatment level component indicating whether the medical device is to be biased to deliver higher intensity electrical stimulation or lower intensity electrical stimulation more often, or a responsiveness level component indicating whether the medical device is to be biased to adjust the delivery of electrical stimulation more often or less often. In this example, the medical device may automatically adjust a center target of the homeostatic window or a homeostatic window range of the homeostatic window to generate an adjusted homeostatic window.Docket No.: A0013938W001

[0039] As another example, for ST mode, the closed-loop feedback policy may define a bioelectric signal threshold for a bioelectric signal. The request to adjust the closed-loop feedback policy may not define an adjusted bioelectric signal threshold. In this example, the request may include a boost mode intensity component indicating whether the medical device is biased to deliver electrical stimulation more often at a first intensity or a second intensity. In this example, the medical device may automatically adjust the bioelectric signal threshold to generate an adjusted bioelectric signal threshold by biasing the medical device to deliver electrical stimulation more often at a first intensity than a second intensity, as indicated in the boost mode intensity component.

[0040] In one or more examples, the adjustment to the closed-loop feedback policy may bias the medical device to deliver electrical stimulation more often, or more often at a higher or lower stimulation intensity. However, such an adjustment to the closed-loop feedback policy may not require that electrical stimulation is actually delivered more often, or that electrical stimulation at a higher stimulation intensity is actually delivered more often than at a lower stimulation intensity, or vice-versa. The actual stimulation intensity may still be controlled by the sensed bioelectric signal. The example techniques may bias (e.g., increase or decrease the likelihood) the medical device to deliver electrical stimulation more often, or more often at a higher or lower stimulation intensity response to the request to adjust the closed-loop feedback policy.

[0041] Furthermore, in some examples, the medical device may be configured to automatically select between the DT mode and the ST mode. For instance, the medical device may default to operation in the DT mode. If the stimulation intensity (e.g., amplitude of the current of the electrical stimulation) increases above a threshold, the medical device may switch from DT mode to ST mode. Once in ST mode, if a duty cycle, as described in more detail, falls below a threshold, the medical device may switch back from ST mode to DT mode.

[0042] FIG. 1 is a conceptual diagram illustrating an example system 100 that includes an implantable medical device (IMD) 106 configured to deliver DBS to a patient 112 according to an example of the techniques of the disclosure. In some examples, DBS may be adaptive (aDBS) in the sense that IMD 106 may adjust, increase, or decrease the value of one or more stimulation parameters of electrical stimulation that define the DBS in response to changes in patient activity or movement, a severity of one or more symptoms of a disease of the patient, a presence of one or more side effects due to the DBS, or one or more sensed signals of the patient, etc. For example, system 100 may use a bioelectric signal, e.g., an LFP signal, of patient 112 as a control signal such that the IMD 106 adjusts the magnitude of the one or more parameters of the electrical stimulation in response to the magnitude or change in magnitude of characteristic values, e.g., an amplitude, of the bioelectric signal. This process enables system 100 toDocket No.: A0013938W001 automatically adjust stimulation therapy in response to changes to the patient condition, such as changes to brain activity indicative of a level of therapy efficacy.

[0043] Example therapy system 100 includes medical device programmer 104, IMD 106, lead extension 110, and leads 114A and 114B with respective sets of electrodes 116, 118. In the example shown in FIG. 1, electrodes 116, 118 of leads 114 A, 114B are positioned to deliver electrical stimulation to a tissue site within brain 120, such as a deep brain site under the dura mater of brain 120 of patient 112. In some examples, delivery of stimulation to one or more regions of brain 120, such as the subthalamic nucleus, globus pallidus or thalamus, may be an effective treatment to manage movement disorders, such as Parkinson’s disease. Some or all of electrodes 116, 118 also may be positioned to sense the bioelectric signal within brain 120 of patient 112. In some examples, some of electrodes 116, 118 may be configured to sense the bioelectric signal and others of electrodes 116, 118 may be configured to deliver adaptive electrical stimulation to brain 120. In other examples, all of electrodes 116, 118 are configured to both sense the bioelectric signal and deliver adaptive electrical stimulation to brain 120.

[0044] IMD 106 includes a therapy module (e.g., which may include processing circuitry, signal generation circuitry or other electrical circuitry configured to perform the functions attributed to IMD 106) that includes a stimulation generator configured to generate and deliver electrical stimulation therapy to patient 112 via a subset of electrodes 116, 118 of leads 114A and 114B, respectively. The subset of electrodes 116, 118 that are used to deliver electrical stimulation to patient 112, and, in some cases, the polarity of the subset of electrodes 116, 118, may be referred to as a stimulation electrode combination. As described in further detail below, the stimulation electrode combination can be selected for a particular patient 112 and target tissue site (e.g., selected based on bioelectric signal information and the patient condition). The group of electrodes 116, 118 includes at least one electrode and can include a plurality of electrodes. In some examples, the plurality of electrodes 116 and / or 118 may have a complex electrode geometry such that two or more electrodes are located at different positions around the perimeter of the respective lead.

[0045] According to some techniques of the disclosure, system 100, via IMD 106, delivers electrical stimulation therapy defined by one or more parameters, such as voltage or current amplitude within a therapeutic window (e.g., a window defined by one or more limits for the voltage or current amplitude), adjusted based on the characteristic the bioelectric signal feature and the one or more threshold values. System 100 may continuously monitor the bioelectric signal feature.

[0046] In some examples, system 100 adjusts the parameter of the electrical stimulation therapy adjusted in response to the bioelectric signal falling outside the one or more thresholdDocket No.: A0013938W001 values. In some examples, the one or more threshold values include one or more of an upper threshold or a lower threshold that forms a homeostatic window. The homeostatic window may be used as part of an adaptive mode for adjusting stimulation therapy over time. In some examples, system 100 may change other parameters in response to sensed signals such as stimulation pulse frequency, pulse burst duration, pulse burst frequency, duty cycle, or electrode combination. Throughout this disclosure, the terms “limit,” “threshold,” and “bound” can refer to similar concepts, e.g., each defines a window or range of acceptable values associated with adaptive therapy. Although the homeostatic window may be described as including an upper and lower threshold, only a single threshold (e.g., upper threshold or lower threshold) may be used in other examples.

[0047] That is, IMD 106 may be configured to operate in dual threshold (DT) mode or in single threshold (ST) mode. In DT mode, IMD 106 may define a homeostatic window with upper threshold and lower threshold. In ST mode, IMD 106 may define a single bioelectric signal threshold. In either case, a closed-loop feedback policy may define the homeostatic window in DT mode or the bioelectric signal threshold in ST mode. In DT mode or ST mode, IMD 106 may be configured to deliver electrical stimulation that reduce or suppresses symptoms of patient 112.

[0048] As described herein, “reducing” or “suppressing” the symptoms of the patient refer to alleviating, in whole or in part, the severity of one or more symptoms of the patient. In one example, the clinician makes a determination of the severity of one or more symptoms of Parkinson’s disease of patient 112 with reference to the Unified Parkinson's Disease Rating Scale (UPDRS) or the Movement Disorder Society-Sponsored Revision of the Unified Parkinson’s Disease Rating Scale (MDS-UPDRS). A discussion of the application of the MDS-UPDRS is provided by Movement Disorder Society-Sponsored Revision of the Unified Parkinson’s Disease Rating Scale (MDS-UPDRS): Scale Presentation and Clinimetric Testing Results, C. Goetz et al, Movement Disorders, Vol. 23, No. 15, pp. 2129-2170 (2008).

[0049] As described herein, system 100 can monitor one or more signals of patient 112 for selecting one or more parameters defining stimulation and / or adjusting stimulation in a closed-loop feedback manner. In one example, the signal is a bioelectric signal of patient 112, such as an LFP signal with a frequency within an Alpha-Beta frequency band and / or a Gamma frequency band of the brain of patient 112. For example, the sensed bioelectric signal may be a power of the respective Alpha-Beta frequency band and / or Gamma frequency band. In yet a further example, the signal can be a signal indicative of a bioelectric parameter of the patient, such as a severity of a symptom of the patient, a movement of the patient, a posture of the patient, a respiratory function of the patient, a heart rate, or an activity level of the patient.Docket No.: A0013938W001

[0050] System 100 may use a single signal or combination of different signals for initially selecting and / or adjusting one or more parameters that define subsequent electrical stimulation therapy. System 100, via IMD 106, can be configured to deliver electrical stimulation to patient 112, wherein one or more parameters defining the electrical stimulation are related by a transfer function (which may or may not be proportional to the magnitude of the monitored signal or adjusted in response to a magnitude of the monitored signal exceeding one or more thresholds).

[0051] System 100 may be configured to treat one or more patient conditions, such as a movement disorder, neurodegenerative impairment, a mood disorder, or a seizure disorder of patient 112. Patient 112 ordinarily is a human patient. In some cases, however, therapy system 100 may be applied to other mammalian or non-mammalian, non-human patients. While movement disorders and neurodegenerative impairment are primarily referred to herein, in other examples, therapy system 100 may provide therapy to manage symptoms of other patient conditions, such as, but not limited to, seizure disorders (e.g., epilepsy) or mood (or psychological) disorders (e.g., major depressive disorder (MDD), bipolar disorder, anxiety disorders, post-traumatic stress disorder, dysthymic disorder, and obsessive-compulsive disorder (OCD)). At least some of these disorders may be manifested in one or more patient movement behaviors. As described herein, a movement disorder or other neurodegenerative impairment may include symptoms such as, for example, muscle control impairment, motion impairment or other movement problems, such as rigidity, spasticity, bradykinesia, rhythmic hyperkinesia, nonrhythmic hyperkinesia, and akinesia. In some cases, the movement disorder may be a symptom of Parkinson’s disease. However, the movement disorder may be attributable to other patient conditions.

[0052] In some examples, the bioelectric signals sensed within brain 120 may reflect changes in electrical current produced by the sum of electrical potential differences across brain tissue, or any voltage potentials between electrodes. In some examples, the bioelectric signal that is used to select a stimulation electrode combination may be sensed within the same region of brain 120 as the target tissue site for the electrical stimulation. As previously indicated, these tissue sites may include tissue sites within anatomical structures such as the thalamus, subthalamic nucleus or globus pallidus of brain 120, as well as other target tissue sites. The specific target tissue sites and / or regions within brain 120 may be selected based on the patient condition. Thus, in some examples, the electrodes used for delivering electrical stimulation may be different than the electrodes used for sensing the bioelectric signal. In other examples, the same electrodes may be used to deliver electrical stimulation and sense brain signals. However, this configuration may require system 100 to switch between stimulation generation and sensing circuitry and may reduce the time system 100 can sense brain signals.Docket No.: A0013938W001

[0053] Electrical stimulation generated by IMD 106 may be configured to manage a variety of disorders and conditions. In some examples, the stimulation generator of IMD 106 is configured to generate and deliver electrical stimulation pulses to patient 112 via electrodes of a selected stimulation electrode combination. However, in other examples, the stimulation generator of IMD 106 may be configured to generate and deliver a continuous wave signal, e.g., a sine wave or triangle wave. In either case, a stimulation generator within IMD 106 may generate the electrical stimulation therapy for DBS according to a therapy program that is selected at that given time in therapy. In examples in which IMD 106 delivers electrical stimulation in the form of stimulation pulses, a therapy program may include a set of therapy parameter values (e.g., stimulation parameters), such as a stimulation electrode combination for delivering stimulation to patient 112, pulse frequency, pulse width, stimulation cycling, and a current or voltage amplitude of the pulses. As previously indicated, the electrode combination may indicate the specific electrodes 116, 118 that are selected to deliver stimulation signals to tissue of patient 112 and the respective polarities of the selected electrodes. In some examples, a clinician may set up a plurality of therapy programs that patient 112 can manually switch between and / or that IMD 106 can cycle through. Based on patient feedback and / or sensed signals, the clinician, the patient, and / or IMD 106 may select a therapy program for subsequent use.

[0054] IMD 106 may be implanted within a subcutaneous pocket above the clavicle, or, alternatively, on or within cranium 122 or at any other suitable site within patient 112. Generally, IMD 106 is constructed of a biocompatible material that resists corrosion and degradation from bodily fluids. IMD 106 may comprise a hermetic housing to substantially enclose components, such as a processor, therapy module, and memory.

[0055] As shown in FIG. 1, implanted lead extension 110 is coupled to IMD 106 via connector 108 (also referred to as a connector block or a header of IMD 106). In the example of FIG. 1, lead extension 110 traverses from the implant site of IMD 106 and along the neck of patient 112 to cranium 122 of patient 112 to access brain 120. In the example shown in FIG. 1, leads 114A and 114B (collectively “leads 114”) are implanted within the right and left hemispheres, respectively, of patient 112 in order deliver electrical stimulation to one or more regions of brain 120, which may be selected based on the patient condition or disorder controlled by therapy system 100. In some examples, more than two leads may be used in total or in each hemisphere, e.g., two leads per hemisphere (4 leads total), or an uneven number of leads between the hemispheres. The specific target tissue site and the stimulation electrodes used to deliver stimulation to the target tissue site, however, may be selected, e.g., according to the identified patient behaviors and / or other sensed patient parameters. Other lead 114 and IMD 106 implantDocket No.: A0013938W001 sites are contemplated. For example, IMD 106 may be implanted on or within cranium 122, in some examples. Or leads 114 may be implanted within the same hemisphere or IMD 106 may be coupled to a single lead implanted in a single hemisphere.

[0056] Existing lead sets include axial leads carrying ring electrodes disposed at different axial positions and so-called “paddle” leads carrying planar arrays of electrodes. Selection of electrode combinations within an axial lead, a paddle lead, or among two or more different leads presents a challenge to the clinician. In some examples, more complex lead array geometries may be used.

[0057] Although leads 114 are shown in FIG. 1 as being coupled to a common lead extension 110, in other examples, leads 114 may be coupled to IMD 106 via separate lead extensions or directly to connector 108. Leads 114 may be positioned to deliver electrical stimulation to one or more target tissue sites within brain 120 to manage patient symptoms associated with a movement disorder of patient 112. Leads 114 may be implanted to position electrodes 116, 118 at desired locations of brain 120 through respective holes in cranium 122. Leads 114 may be placed at any location within brain 120 such that electrodes 116, 118 are capable of providing electrical stimulation to target tissue sites within brain 120 during treatment. For example, electrodes 116, 118 may be surgically implanted under the dura mater of brain 120 or within the cerebral cortex of brain 120 via a burr hole in cranium 122 of patient 112, and electrically coupled to IMD 106 via one or more leads 114.

[0058] In the example shown in FIG. 1, electrodes 116, 118 of leads 114 are shown as ring electrodes. Ring electrodes may be used in aDBS applications because they are relatively simple to program and are capable of delivering an electrical field to any tissue adjacent to electrodes 116, 118. In other examples, electrodes 116, 118 may have different configurations. For example, in some examples, at least some of the electrodes 116, 118 of leads 114 may have a complex electrode array geometry that is capable of producing shaped electrical fields. The complex electrode array geometry may include multiple electrodes (e.g., partial ring or segmented electrodes) around the outer perimeter of each lead 114, rather than one ring electrode. In this manner, electrical stimulation may be directed in a specific direction from leads 114 to enhance therapy efficacy and reduce possible adverse side effects from stimulating a large volume of tissue. In some examples, a housing of IMD 106 may include one or more stimulation and / or sensing electrodes. In alternative examples, leads 114 may have shapes other than elongated cylinders as shown in FIG. 1. For example, leads 114 may be paddle leads, spherical leads, bendable leads, or any other type of shape effective in treating patient 112 and / or minimizing invasiveness of leads 114.Docket No.: A0013938W001

[0059] In the example shown in FIG. 1, IMD 106 includes a memory to store a plurality of therapy programs that each define a set of therapy parameter values. In some examples, IMD 106 may select a therapy program from the memory based on various parameters, such as sensed patient parameters and the identified patient behaviors. IMD 106 may generate electrical stimulation based on the selected therapy program to manage the patient symptoms associated with a movement disorder.

[0060] External programmer 104 wirelessly communicates with IMD 106 as needed to provide or retrieve therapy information. Programmer 104 is an external computing device that a user, e.g., a clinician and / or patient 112, may use to communicate with IMD 106. For example, programmer 104 may be a clinician programmer that the clinician uses to communicate with IMD 106 and program one or more therapy programs for IMD 106. Alternatively, programmer 104 may be a patient programmer that allows patient 112 to select programs and / or view and modify therapy parameters. The clinician programmer may include more programming features than the patient programmer. In other words, more complex or sensitive tasks may only be allowed by the clinician programmer to prevent an untrained patient from making undesirable changes to IMD 106.

[0061] When programmer 104 is configured for use by the clinician, programmer 104 may be used to transmit initial programming information to IMD 106. This initial information may include hardware information, such as the type of leads 114 and the electrode arrangement, the position of leads 114 within brain 120, the configuration of electrode array 116, 118, initial programs defining therapy parameter values, and any other information the clinician desires to program into IMD 106. Programmer 104 may also be capable of completing functional tests (e.g., measuring the impedance of electrodes 116, 118 of leads 114). In addition, or as an alternative, to programmer 104, a different external computing device may perform any of the functionality of programmer 104. The external computing device may be a networked device and in communication with IMD 106 directly or via programmer 104.

[0062] The clinician may also store therapy programs within IMD 106 with the aid of programmer 104. During a programming session, system 100 may determine one or more therapy programs that may provide efficacious therapy to patient 112 to address symptoms associated with the patient condition, and, in some cases, specific to one or more different patient states, such as a sleep state, movement state or rest state. For example, system 100 may select one or more stimulation electrode combinations with which stimulation is delivered to brain 120. During the programming session, system 100 may evaluate the efficacy of the specific program being evaluated based on feedback provided by the clinician or patient 112 or based on one or more physiological parameters of patient 112 (e.g., muscle activity, muscle tone, rigidity, tremor,Docket No.: A0013938W001 etc.). Alternatively, identified patient behavior from video information may be used as feedback during the initial and subsequent programming sessions.

[0063] Programmer 104 may also be configured for use by patient 112. When configured as a patient programmer, programmer 104 may have limited functionality (compared to a clinician programmer) in order to prevent patient 112 from altering critical functions of IMD 106 or applications that may be detrimental to patient 112. In this manner, programmer 104 may only allow patient 112 to mark events and to adjust values for certain therapy parameters or set an available range of values for a particular therapy parameter. When programmer 104 is configured for use by patient 112 (e.g., a patient programmer), programmer 104 may have a limited set of adjustments and / or data available to the user compared with a clinician programmer. In this manner, the patient programmer version may prevent the patient from causing detrimental changes to therapy but allow the patient to make some adjustments to therapy as desired.

[0064] Therapy system 100 may be implemented to provide chronic stimulation therapy to patient 112 over the course of several months or years. However, system 100 may also be employed on a trial basis to evaluate therapy before committing to full implantation. If implemented temporarily, some components of system 100 may not be implanted within patient 112. For example, patient 112 may be fitted with an external medical device, such as a trial stimulator, rather than IMD 106. The external medical device may be coupled to percutaneous leads or to implanted leads via a percutaneous extension. If the trial stimulator indicates DBS system 100 provides effective treatment to patient 112, the clinician may implant a chronic stimulator within patient 112 for relatively long-term treatment.

[0065] Although IMD 104 is described as delivering electrical stimulation therapy to brain 120, IMD 106 may be configured to direct electrical stimulation to other anatomical regions of patient 112 in other examples. As examples, IMD 106 may be configured to sacral neuromodulation therapy or tibial neuromodulation therapy. In some examples, system 100 may include an implantable drug pump in addition to, or in place of, IMD 106. Further, an IMD may provide other electrical stimulation such as spinal cord stimulation to treat a movement disorder.

[0066] In one or more examples, for closed-loop feedback therapy, such as aDBS, IMD 106 may be programmed with a default closed-loop feedback policy. As one example, for DT mode, IMD 106 may sense the bioelectric signal over a period of time (e.g., 14 days limited to daytime hours), and determine an approximate average of the sensed bioelectric signal over the period of time. The average (e.g., daytime average that excludes nighttime LFP values) of the sensed bioelectric signal over the period of time may form the center target of the homeostatic window, and IMD 106 may determine the width of the homeostatic window to be + 25% of the average. For ST mode, IMD 106 may set the average of the sensed bioelectric signal as the bioelectricDocket No.: A0013938W001 signal threshold. In some examples, IMD 106 may periodically self-adjust the homeostatic window for DT mode or the bioelectric signal threshold for ST mode (e.g., self-adjust the closed-loop feedback policy) based on more recent sensed signals.

[0067] However, in some examples, a user (e.g., clinician, caregiver, or patient 112) may desire to adjust the closed-loop feedback policy to achieve a desired therapy goal. For example, patient 112 may experience better results if electrical stimulation with higher intensity (e.g., amplitude) is delivered more often, or power savings may be more important, and lower intensity electrical stimulation may need to be delivered more often. Patient 112 may also experience better results if electrical stimulation is delivered with small changes in the sensed bioelectric signal or may experience better results only if electrical stimulation is delivered due to larger changes in the sensed bioelectric signal.

[0068] Even with adjustments to the closed-loop feedback policy, the sensed bioelectric signal may still control whether stimulation intensity (e.g., amplitude, pulse width, frequency, etc.) are modified or not. However, with the adjustments to the closed-loop feedback policy, IMD 106 may be biased towards increasing the likelihood that higher intensity stimulation is delivered more often than lower intensity stimulation, or vice-versa for DT or ST mode, and / or IMD 106 may be biased towards increasing the likelihood that electrical stimulation is adjusted more often or less often (e.g., more often if small changes in the sensed bioelectric signal cause change in electrical stimulation, and less often if small changes in the sensed bioelectric signal do not cause change in electrical stimulation).

[0069] Providing a user with manual control of all parameters of the closed-loop feedback policy may cause user frustration or inaccuracies, but providing manual control may still be possible. For example, the user may find it cumbersome to manually set all parameters. As another example, the user may desire to bias IMD 106 in one way, but may enter in parameters that cause IMD 106 to bias in another way.

[0070] Accordingly, in some examples, programmer 104 may provide clinically relevant controls without necessarily providing control over all of the parameters of the closed-loop feedback policy, but control over all parameter is possible. For example, for DT mode, the request to adjust a closed-loop feedback policy that programmer 104 outputs may not define parameters of the homeostatic window, such as the center target or the homeostatic window range. For ST mode, the request to adjust a closed-loop feedback policy that programmer 104 outputs may not define the bioelectric signal threshold. The clinically relevant controls may provide generalized therapy goals.

[0071] As an example, assume that IMD 106 provides DT mode. In this example, programmer 104 may provide a way to control a treatment level component indicating whetherDocket No.: A0013938W001 IMD 106 is to be biased to deliver higher intensity electrical stimulation or lower intensity electrical stimulation more often. As another example, programmer 104 may provide a way to control a responsiveness level component indicating whether IMD 106 is to be biased to adjust the delivery of electrical stimulation more often or less often.

[0072] Assume that IMD 106 provides ST mode. In this example, programmer 104 may provide a way to control a boost mode intensity component indicating whether the medical device is biased to deliver electrical stimulation more often at a first intensity or a second intensity.

[0073] In response to the request to adjust the closed-loop feedback policy, IMD 106 may automatically adjust the homeostatic window for DT mode or the bioelectric signal threshold for ST mode. As described in more detail, IMD 106 may perform a self-centering dual threshold algorithm to automatically adjust the homeostatic window for DT mode or perform a selfcentering single threshold algorithm to automatically adjust the bioelectric signal threshold for ST mode. Furthermore, IMD 106 may be configured to automatically switch between DT mode and ST mode.

[0074] In this manner, the user interface of programmer 104 may be simplified so that the user can focus on clinical variables and generalized therapy goals. That is, no user interaction with the underlying DT mode or ST mode may be necessary, allowing users to rely on traditional expertise. Also, if IMD 106 can automatically switch between DT mode and ST mode, the user may not need to select the operation mode of IMD 106. Furthermore, with the automatic adjustment of the closed-loop feedback policy, IMD 106 may be configured to ensure that the stimulation intensity is kept within certain limits (e.g., no railing).

[0075] As described, this disclosure describes examples related to DT mode, ST mode, and automatic selection of DT mode or ST mode. However, in some examples, it may be possible that IMD 106 implements the techniques related to DT mode, but not ST mode. In some examples, it may be possible that IMD 106 implements the techniques related to ST mode, but not DT mode.

[0076] In some examples, it may be possible that IMD 106 does not implement the techniques related to ST mode or DT mode, but still provides automatic selection between DT mode and ST mode. For example, a user may manually enter parameters for the closed-loop feedback policy for DT mode and ST mode, but once entered, IMD 106 may automatically select whether IMD 106 is to operate in DT mode or ST mode.

[0077] The architecture of system 100 illustrated in FIG. 1 is shown as an example. The techniques as set forth in this disclosure may be implemented in the example system 100 of FIG.1, as well as other types of systems not described specifically herein. Nothing in this disclosureDocket No.: A0013938W001 should be construed so as to limit the techniques of this disclosure to the example architecture illustrated by FIG. 1.

[0078] FIG. 2 is a block diagram of the example IMD 106 of FIG. 1 for delivering DBS therapy according to an example of the techniques of the disclosure, in accordance with one or more techniques of this disclosure. In the example shown in FIG. 2, IMD 106 includes processing circuitry 210, memory 211, stimulation generator 202, sensing module 204, switch module 206, telemetry module 208, sensor 212, and power source 220. Each of these modules may be or may include electrical circuitry configured to perform the functions attributed to each respective module. For example, processing circuitry 210 may include one or more processors as part of the processing circuitry, switch module 206 may include switch circuitry, sensing module 204 may include sensing circuitry, stimulation generator 202 may include stimulation generation circuitry, and telemetry module 208 may include telemetry circuitry. Switch module 204 may not be necessary for multiple current source and sink configurations in which each current source and sink are directly connected to each electrode but may be connected or disconnected via a respective switch. Memory 211 may include any volatile or non-volatile media, such as a random-access memory (RAM), read only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, and the like. Memory 211 may store computer-readable instructions that, when executed by processing circuitry 210, cause IMD 106 to perform various functions. Memory 211 may be a storage device or other non-transitory medium.

[0079] In the example shown in FIG. 2, memory 211 stores patient history 214 and sense electrode combinations and medication information 218 in separate memories within memory 211 or separate areas within memory 211. Patient history 214 includes historical information which may be indicative of one or more of patient state or therapy efficacy, e.g., stimulation therapy efficacy and / or medication efficacy. Patient history 214 may also include the closed-loop feedback policy, such as the homeostatic window information for DT mode and bioelectric signal threshold information for ST mode.

[0080] Memory 211 may include sense and stimulation electrode combinations 218. Sense and stimulation electrode combinations 218 stores sense electrode combinations and associated stimulation electrode combinations. As described above, in some examples, the sense and stimulation electrode combinations may include the same subset of electrodes 116, 118, a housing of IMD 106 functioning as an electrode, or may include different subsets or combinations of such electrodes. Thus, memory 211 can store a plurality of sense electrode combinations and, for each sense electrode combination, store information identifying the stimulation electrode combination that is associated with the respective sense electrodeDocket No.: A0013938W001 combination. The associations between sense and stimulation electrode combinations can be determined, e.g., automatically by processing circuitry 210. In some examples, corresponding sense and stimulation electrode combinations may comprise some or all of the same electrodes. In other examples, however, some or all of the electrodes in corresponding sense and stimulation electrode combinations may be different. For example, a stimulation electrode combination may include more electrodes than the corresponding sense electrode combination in order to increase the efficacy of the stimulation therapy. In some examples, as discussed above, stimulation may be delivered via a stimulation electrode combination to a tissue site that is different than the tissue site closest to the corresponding sense electrode combination but is within the same region, e.g., the thalamus, of brain 120 in order to mitigate any irregular oscillations or other irregular brain activity within the tissue site associated with the sense electrode combination.Alternatively, stimulation may be delivered via one of leads 114, and sensing may be performed via the other lead of leads 114.

[0081] Stimulation generator 202, under the control of processing circuitry 210, generates stimulation signals for delivery to patient 112 via selected combinations of electrodes 116, 118. An example range of electrical stimulation parameters believed to be effective in DBS to manage a movement disorder of patient include:

[0082] 1. Pulse Rate, i.e., Frequency: between approximately 40 Hertz and approximately 500 Hertz, such as between approximately 1 to 185 Hertz or such as approximately 140 Hertz.

[0083] 2. In the case of a voltage controlled system, Voltage Amplitude: between approximately 0.1 volts and approximately 50 volts, such as between approximately 2 volts and approximately 3 volts.

[0084] 3. In the alternative case of a current controlled system, Current Amplitude: between approximately 0.2 milliamps to approximately 100 milliamps, such as between approximately 1.3 milliamps and approximately 2.0 milliamps.

[0085] 4. Pulse Width: between approximately 10 microseconds and approximately 5000 microseconds, such as between approximately 100 microseconds and approximately 1000 microseconds, or between approximately 180 microseconds and approximately 450 microseconds.

[0086] Accordingly, in some examples, stimulation generator 202 generates electrical stimulation signals in accordance with the electrical stimulation parameters noted above, subject to application of the upper and lower limit of a therapeutic window to one or more of the parameters, such that an applicable parameter resides within the range prescribed by the window. Other ranges of therapy parameter values may also be useful and may depend on the targetDocket No.: A0013938W001 stimulation site within patient 112. While stimulation pulses are described, stimulation signals may be of any form, such as continuous-time signals (e.g., sine waves) or the like.

[0087] Processing circuitry 210 may include fixed function processing circuitry and / or programmable processing circuitry, and may comprise, for example, any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), discrete logic circuitry, or any other processing circuitry configured to provide the functions attributed to processing circuitry 210 herein may be embodied as firmware, hardware, software or any combination thereof. Processing circuitry 210 may control stimulation generator 202 according to therapy programs 214 stored in memory 211 to apply particular stimulation parameter values specified by one or more of programs, such as voltage amplitude or current amplitude, pulse width, or pulse rate.

[0088] In the example shown in FIG. 2, the set of electrodes 116 includes electrodes 116A, 116B, 116C, and 116D, and the set of electrodes 118 includes electrodes 118A, 118B, 118C, and 118D. Processing circuitry 210 also controls switch module 206 to apply the stimulation signals generated by stimulation generator 202 to selected combinations of electrodes 116, 118. In particular, switch module 204 may couple stimulation signals to selected conductors within leads 114, which, in turn, deliver the stimulation signals across selected electrodes 116, 118. Switch module 206 may be a switch array, switch matrix, multiplexer, or any other type of switching module configured to selectively couple stimulation energy to selected electrodes 116, 118 and to selectively sense the bioelectric signal with selected electrodes 116, 118. Hence, stimulation generator 202 is coupled to electrodes 116, 118 via switch module 206 and conductors within leads 114. In some examples, however, IMD 106 does not include switch module 206.

[0089] Stimulation generator 202 may be a single channel or multi-channel stimulation generator. In particular, stimulation generator 202 may be capable of delivering a single stimulation pulse, multiple stimulation pulses, or a continuous signal at a given time via a single electrode combination or multiple stimulation pulses at a given time via multiple electrode combinations. In some examples, however, stimulation generator 202 and switch module 206 may be configured to deliver multiple channels on a time-interleaved basis (e.g., pulses from one channel are at least partially alternating with at least some pulses from another channel). For example, switch module 206 may serve to time divide the output of stimulation generator 202 across different electrode combinations at different times to deliver multiple programs or channels of stimulation energy to patient 112. Alternatively, stimulation generator 202 may comprise multiple voltage or current sources and sinks that are coupled to respective electrodes to drive the electrodes as cathodes or anodes. In this example, IMD 106 may not require theDocket No.: A0013938W001 functionality of switch module 206 for time-interleaved multiplexing of stimulation via different electrodes.

[0090] Electrodes 116, 118 on respective leads 114 may be constructed of a variety of different designs. For example, one or both of leads 114 may include two or more electrodes at each longitudinal location along the length of the lead, such as multiple electrodes at different perimeter locations around the perimeter of the lead at each of the locations A, B, C, and D. In one example, the electrodes may be electrically coupled to switch module 206 via respective wires that are straight or coiled within the housing the lead and run to a connector at the proximal end of the lead. In another example, each of the electrodes of the lead may be electrodes deposited on a thin film. The thin film may include an electrically conductive trace for each electrode that runs the length of the thin film to a proximal end connector. The thin film may then be wrapped (e.g., a helical wrap) around an internal member to form the lead 114. These and other constructions may be used to create a lead with a complex electrode geometry.

[0091] Although sensing module 204 is incorporated into a common housing with stimulation generator 202 and processing circuitry 210 in FIG. 2, in other examples, sensing module 204 may be in a separate housing from IMD 106 and may communicate with processing circuitry 210 via wired or wireless communication techniques.

[0092] Sensor 212 may include one or more sensing elements that sense values of a respective patient parameter. For example, sensor 212 may include one or more accelerometers, optical sensors, chemical sensors, temperature sensors, pressure sensors, or any other types of sensors. Sensor 212 may output patient parameter values that may be used as feedback to control delivery of therapy. IMD 106 may include additional sensors within the housing of IMD 106 and / or coupled via one of leads 114 or other leads. In addition, IMD 106 may receive sensor signals wirelessly from remote sensors via telemetry module 208, for example. In some examples, one or more of these remote sensors may be external to patient (e.g., carried on the external surface of the skin, attached to clothing, or otherwise positioned external to the patient).

[0093] Telemetry module 208 supports wireless communication between IMD 106 and an external programmer 104 or another computing device under the control of processing circuitry 210. Processing circuitry 210 of IMD 106 may receive, as updates to programs, values for various stimulation parameters such as magnitude and electrode combination, from programmer 104 via telemetry module 208. The updates to the therapy programs may be stored within therapy programs 214 portion of memory 211. Telemetry module 208 in IMD 106, as well as telemetry modules in other devices and systems described herein, such as programmer 104, may accomplish communication by radiofrequency (RF) communication techniques. In addition, telemetry module 208 may communicate with external medical device programmer 104 viaDocket No.: A0013938W001 proximal inductive interaction of IMD 106 with programmer 104. Accordingly, telemetry module 208 may send information to external programmer 104 on a continuous basis, at periodic intervals, or upon request from IMD 106 or programmer 104.

[0094] Power source 220 delivers operating power to various components of IMD 106. Power source 220 may include a small rechargeable or non-rechargeable battery and a power generation circuit to produce the operating power. Recharging may be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within IMD 220. In some examples, power requirements may be small enough to allow IMD 220 to utilize patient motion and implement a kinetic energy-scavenging device to trickle charge a rechargeable battery. In other examples, traditional batteries may be used for a limited period of time.

[0095] According to the techniques of the disclosure, processing circuitry 210 may receive a request to adjust a closed-loop feedback policy, the closed-loop feedback policy defining a homeostatic window for a bioelectric signal. In some examples, the request does not define a center target or a homeostatic window range for the homeostatic window. For example, the request may include at least one of a treatment level component indicating whether IMD 106 is to be biased to deliver higher intensity electrical stimulation or lower intensity electrical stimulation more often, or a responsiveness level component indicating whether IMD 106 is to be biased to adjust the delivery of electrical stimulation more often or less often.

[0096] Responsive to receiving the request, processing circuitry 210 may automatically adjust at least one of a center target of the homeostatic window or a homeostatic window range of the homeostatic window to generate an adjusted homeostatic window. Processing circuity 210 may utilize the adjusted homeostatic window to control delivery of the electrical stimulation. For example, processing circuitry 210, via sensing module 204, may receive characteristic information of a sensed bioelectric signal. Processing circuitry 210 may adjust delivery of electrical stimulation based on the characteristic information and the adjusted homeostatic window.

[0097] The above example techniques may be applicable for DT mode. For ST mode, processing circuitry 210 may receive a request to adjust a closed-loop feedback policy, the closed-loop feedback policy defining a bioelectric signal threshold for a bioelectric signal. The request may not define the adjusted bioelectric signal threshold. The request may include a boost mode intensity component indicating whether IMD 106 is biased to deliver electrical stimulation more often at a first intensity or a second intensity.

[0098] Responsive to the request, processing circuitry 210 may automatically adjust the bioelectric signal threshold to generate an adjusted bioelectric signal threshold by biasing IMDDocket No.: A0013938W001 106 to deliver electrical stimulation more often at a first intensity than a second intensity.Processing circuity 210 may utilize the adjusted bioelectric signal threshold to control delivery of the electrical stimulation. For example, processing circuitry 210, via sensing module 204, may receive characteristic information of a sensed bioelectric signal. Processing circuitry 210 may adjust delivery of electrical stimulation based on the characteristic information and the adjusted bioelectric signal threshold.

[0099] As described, processing circuitry 210 may bias IMD 106 to deliver electrical stimulation more often at a first intensity than a second intensity. In ST mode, when the sensed bioelectric signal goes above the bioelectric signal threshold, IMD 106 may increase the intensity of the electrical stimulation (e.g., increase the current or voltage amplitude). When the sensed bioelectric signal goes below the bioelectric signal threshold, IMD 106 may decrease the intensity of the electrical stimulation (e.g., decrease the current or voltage amplitude). In this manner, processing circuitry 210 may toggle intensity at which electrical stimulation is delivered between a first intensity and a second intensity based on whether the sensed bioelectric signal is greater than or less than the bioelectric signal threshold.

[0100] Accordingly, if processing circuitry 210 were to bias IMD 106 to deliver electrical stimulation at the first intensity more often than the second intensity, then processing circuitry 210 may increase or decrease the bioelectric signal threshold so that IMD 106 delivers electrical stimulation in the manner that IMD 106 is biased. As an example, assume that the first intensity is greater than the second intensity, and based on the boost mode intensity component indicating that IMD 106 is biased to deliver electrical stimulation more often at a first intensity or a second intensity, processing circuitry 210 may lower (e.g., decrease) the bioelectric signal threshold. The result may be that the sensed bioelectric signal is likely to more often be above the bioelectric signal threshold, causing delivery of electrical stimulation at the first intensity, than below the bioelectric signal threshold, at which delivery of electrical stimulation is at the second intensity.

[0101] As another example, assume that the first intensity is less than the second intensity, and based on the boost mode intensity component indicating that IMD 106 is biased to deliver electrical stimulation more often at a first intensity or a second intensity, processing circuitry 210 may increase the bioelectric signal threshold. The result may be that the sensed bioelectric signal is likely to more often be below the bioelectric signal threshold, causing delivery of electrical stimulation at the first intensity, than above the bioelectric signal threshold, at which delivery of electrical stimulation is at the second intensity.

[0102] Processing circuitry 210 may be configured to automatically determine the operation mode of IMD 106. For example, processing circuitry 210 may determine a stimulation intensity at which IMD 106 is delivering electrical stimulation. Based on the stimulation intensity,Docket No.: A0013938W001 processing circuitry 210 may select an operation mode as one of a dual threshold mode or a single threshold mode. As described, in the dual threshold mode, IMD 106 determines adjustment to delivery of electrical stimulation based on characteristics of a first sensed bioelectric signal being outside an upper threshold and a lower threshold of the dual threshold mode (e.g., greater than the upper threshold of the homeostatic window or less than the lower threshold of the homeostatic window). In the single threshold mode, IMD 106 determines adjustment to delivery of the electrical stimulation based on characteristics of a second sensed bioelectric signal being greater than or less than a single bioelectric signal threshold.

[0103] Processing circuitry 210 may cause IMD 106 to operate in the selected operation mode. For instance, the first sensed bioelectric signal may be an LFP signal sampled at a first sampling rate (e.g., 1-50 Hz, such as less than or equal to 5 Hz), and the second sensed bioelectric signal may be the LFP signal sampled at a second sampling rate that is greater than the first sampling rate (e.g., 1-50 Hz, such as less than or equal to 20 Hz). That is, the second sensed bioelectric signal may be the LFP signal sampled at a sampling rate that is greater than the sampling rate at which the first sensed bioelectric signal is sampled.

[0104] FIG. 3 is a block diagram of the external programmer of FIG. 1 for controlling delivery of DBS therapy according to an example of the techniques of the disclosure. FIG. 3 is a block diagram of the external programmer 104 of FIG. 1. Although programmer 104 may generally be described as a hand-held device, programmer 104 may be a larger portable device or a more stationary device. In some examples, programmer 104 may be referred to as a tablet computing device. In addition, in other examples, programmer 104 may be included as part of an external charging device or include the functionality of an external charging device. As illustrated in FIG. 3, programmer 104 may include processing circuitry 310, memory 311, user interface 302, telemetry module 308, and power source 320. Memory 311 may store instructions that, when executed by processing circuitry 310, cause processing circuitry 310 and external programmer 104 to provide the functionality ascribed to external programmer 104 throughout this disclosure. Each of these components, or modules, may include electrical circuitry that is configured to perform some or all of the functionality described herein. For example, processing circuitry 310 may include processing circuitry configured to perform the processes discussed with respect to processing circuitry 310.

[0105] In general, programmer 104 comprises any suitable arrangement of hardware, alone or in combination with software and / or firmware, to perform the techniques attributed to programmer 104, and processing circuitry 310, user interface 302, and telemetry module 308 of programmer 104. In various examples, programmer 104 may include one or more processors, which may include fixed function processing circuitry and / or programmable processing circuitry,Docket No.: A0013938W001 as formed by, for example, one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. Programmer 104 also, in various examples, may include a memory 311, such as RAM, ROM, PROM, EPROM, EEPROM, flash memory, a hard disk, or an optical media (e.g., DVD or CD-ROM), comprising executable instructions for causing the one or more processors to perform the actions attributed to them. Moreover, although processing circuitry 310 and telemetry module 308 are described as separate modules, in some examples, processing circuitry 310 and telemetry module 308 may be functionally integrated with one another. In some examples, processing circuitry 310 and telemetry module 308 correspond to individual hardware units, such as ASICs, DSPs, FPGAs, or other hardware units.

[0106] Memory 311 (e.g., a storage device) may store instructions that, when executed by processing circuitry 310, cause processing circuitry 310 and programmer 104 to provide the functionality ascribed to programmer 104 throughout this disclosure. For example, memory 311 may include instructions that cause processing circuitry 310 to select one or more parameters for electrical stimulation or adaptive stimulation according to sensed signals or receive user input and send a corresponding command to IMD 104, or instructions for any other functionality. In addition, memory 311 may include a plurality of programs, where each program includes a parameter set that defines stimulation therapy.

[0107] User interface 302 may include a button or keypad, lights, a speaker for voice commands, a display, such as a liquid crystal (LCD), light-emitting diode (LED), or organic light-emitting diode (OLED). In some examples the display may be a touch screen. User interface 302 may be configured to display any information related to the delivery of stimulation therapy, identified patient behaviors, sensed patient parameter values, automatically selected parameters, prompts for user input regarding stimulation parameters or adaptive stimulation parameters, patient behavior criteria, or any other such information. User interface 302 may also receive user input via user interface 302. The input may be, for example, in the form of pressing a button on a keypad or selecting an icon from a touch screen. User interface 302 may refer to hardware configured to present information to the user and / or receive input from the user. In some examples, processing circuitry 310 directly controls this hardware. In other examples, processing circuitry 310 may communicate with drive hardware that controls hardware of user interface 302. In some examples, user interface 302 may include display and / or interactive display configurations as described herein.

[0108] Telemetry module 308 may support wireless communication between IMD 106 and programmer 104 under the control of processing circuitry 310. Telemetry module 308 may also be configured to communicate with another computing device via wireless communicationDocket No.: A0013938W001 techniques, or direct communication through a wired connection. In some examples, telemetry module 308 provides wireless communication via an RF or proximal inductive medium. In some examples, telemetry module 308 includes an antenna, which may take on a variety of forms, such as an internal or external antenna. In some examples, telemetry modules 308 may support communications with intermediate devices between programmer 104 and IMD 106 or other external devices.

[0109] Examples of local wireless communication techniques that may be employed to facilitate communication between programmer 104 and IMD 106 include RF communication according to the 802.11 or Bluetooth specification sets or other standard, inductive telemetry, or any proprietary telemetry protocols. In this manner, other external devices may be capable of communicating with programmer 104 without needing to establish a secure wireless connection. As described herein, telemetry module 308 may be configured to transmit a spatial electrode movement pattern or other stimulation parameter values to IMD 106 for delivery of stimulation therapy.

[0110] In one or more examples, programmer 104 may provide limited clinically relevant options to the user that the user can use to output a request to adjust a closed-loop feedback policy. As one example, for DT mode, programmer 104 may display a treatment level UI (e.g., button, slide, turn knob, etc.) and / or display a responsiveness level UI. The treatment level UI may control a treatment level component of a request to adjust a closed-loop feedback policy and the responsiveness level UI may control a responsiveness level component of the request to adjust the closed-loop feedback policy. For DT mode, the closed-loop feedback policy may define a homeostatic window for a bioelectric signal. The treatment level component may indicate whether IMD 106 is to be biased to deliver higher intensity electrical stimulation or lower intensity electrical stimulation more often. The responsiveness level component may indicate whether IMD 106 is to be biased to adjust the delivery of electrical stimulation more often or less often.[oni] For ST mode, programmer 104 may display a boost mode intensity UI. The boost mode intensity UI may control a boost mode intensity component of a request to adjust a closed-loop policy. For ST mode, the closed-loop feedback policy may define a single bioelectric signal threshold for a bioelectric signal. The boost mode intensity component may indicate whether IMD 106 is biased to deliver electrical stimulation more often at the first intensity or the second intensity. In some examples, programmer 104 may also allow the user to input in average intensity thresholds that are used to adjust the bioelectric signal threshold.

[0112] In one or more examples, programmer 104 (e.g., patient programmer or clinician programmer) may output the request to adjust the closed-loop feedback policy. The request mayDocket No.: A0013938W001 not define the center target or the homeostatic window range for the homeostatic window for DT mode, or an adjusted bioelectric signal threshold for ST mode. Programmer 104 may output the request that includes the treatment level component and / or responsiveness level component for DT mode, or the boost mode intensity component for ST mode. IMD 106 may then automatically adjust the closed-loop feedback policy.

[0113] In some examples, programmer 104 may be configured to automatically determine the parameters for the closed-loop feedback policy. Programmer 104 may transmit the parameters to IMD 106. The parameters may be the center target of the homeostatic window and the homeostatic window range for DT mode, or may be the bioelectric signal threshold for ST mode.

[0114] FIG. 4 is a flow diagram illustrating example techniques of automatically adjusting a closed-loop feedback policy for a dual threshold operational mode. In the example of FIG. 4, processing circuitry 210 may include homeostatic window generator 400, comparator 402, and stimulation generator controller 406. Comparator 416 may be optional for examples where wake-up detection is used. FIG. 4 also illustrates IMD 106 as including bioelectric sensor 410, which may be part of sensing module 204.

[0115] Homeostatic window generator 400 may have generated an initial homeostatic window. For instance, homeostatic window generator 400 may have received sensed bioelectric signals over 14 days (e.g., during normal daylight hour), and determined the average bioelectric signal. Homeostatic window generator 400 may set the center target equal to the average, and some absolute value around the center target for the upper and lower thresholds of the homeostatic window (+ 25% of the average as the upper threshold, and -25% of the average as the lower threshold). Homeostatic window generator 400 may also determine an upper limit for the upper threshold, and a lower limit for the lower threshold. The upper limit may be the maximum or some percentage (e.g., 95%) of the maximum bioelectric signal. The lower limit may be the minimum or some percentage of the minimum bioelectric signal. In some examples, the upper limit and the lower limit may be based on pre-defined limits. There may be various other ways in which homeostatic window generator may generate an initial homeostatic window, and the techniques are not limited to any particular example. The upper limits and the lower limit may be part of the closed-loop feedback policy.

[0116] Processing circuitry 210 may receive a request to adjust a closed-loop feedback policy, the closed-loop feedback policy defining a homeostatic window for a bioelectric signal. The request may include a treatment level component indicating whether IMD 106 is to be biased to deliver higher intensity electrical stimulation or lower intensity electrical stimulation more often, or may include a responsiveness level component indicating whether IMD 106 is to be biased to adjust the delivery of electrical stimulation more often or less often.Docket No.: A0013938W001

[0117] In some examples, processing circuitry 210 may determine a homeostatic window range based on the responsiveness level component. For instance, if IMD 106 is to adjust electrical stimulation more often (e.g., is more responsive to small changes in the bioelectric signal), homeostatic window generator 400 may narrow the homeostatic window range (e.g., the upper threshold and lower threshold are closer). This way, minor changes in the bioelectric signal may result in the bioelectric signal crossing the upper threshold or lower threshold, which can trigger an adjustment to the electrical stimulation. If IMD 106 is to deliver electrical stimulation less often (e.g., is less responsive to small changes in the bioelectric signal), homeostatic window generator 400 may widen the homeostatic window range (e.g., the upper threshold and lower threshold are further apart). This way, minor changes in the bioelectric signal may not result in the bioelectric signal crossing the upper threshold or lower threshold, which limits how often an adjustment to the electrical stimulation is triggered.

[0118] Processing circuitry 210 may determine a center target of the homeostatic window (e.g., centering at 50% within the homeostatic window) based on the treatment level component indicating whether IMD 106 is to be biased to deliver higher intensity electrical stimulation or lower intensity electrical stimulation more often. For instance, if IMD 106 is to deliver higher intensity electrical stimulation more often, homeostatic window generator 400 may lower the center target towards a lower limit of the homeostatic window, resulting in lowering of the upper threshold and the lower threshold. This way, the bioelectric signal is more likely to be greater than the upper threshold of the homeostatic window, resulting in IMD 106 delivering higher intensity electrical stimulation. If IMD 106 is to deliver lower intensity electrical stimulation more often, homeostatic window generator 400 may raise the center target towards an upper limit of the homeostatic window, resulting in raising the upper threshold and the lower threshold. This way, the bioelectric signal is more likely to be less than the lower threshold of the homeostatic window, resulting in IMD 106 delivering lower intensity electrical stimulation.

[0119] In this manner, homeostatic window generator 400 may, responsive to receiving the request, automatically adjust at least one of a center target of the homeostatic window or a homeostatic window range of the homeostatic window to generate an adjusted homeostatic window. In some examples, the adjusting of the homeostatic window range or the center target of the homeostatic window range may have an impact on each other. For instance, if raising the center target results in the upper threshold of the homeostatic window going above the upper limit, homeostatic window generator 400 may narrow the homeostatic window range so that the upper threshold of the homeostatic window does not become greater than the upper limit. If lowering the center target results in the lower threshold of the homeostatic window going belowDocket No.: A0013938W001 the lower limit, homeostatic window generator 400 may narrow the homeostatic window range so that the lower threshold of the homeostatic window does not become less than the lower limit.

[0120] Comparator 402 may receive the adjusted homeostatic window, and receive sensed bioelectric signal 412 from bioelectric sensor 410. For instance, bioelectric sensor 410 may receive bioelectric signals (e.g., LFP signals) 408 from patient 112. Bioelectric sensor 410 may sample the bioelectric signals 408 at a particular sampling rate (e.g., 1-50 Hz, such as 5 Hz), and the output may be sensed bioelectric signal 412.

[0121] Comparator 402 may compare the sensed bioelectric signal 412 to the adjusted homeostatic window, and the result may be error signal 404. For example, if sensed bioelectric signal 412 is greater than the upper threshold of the homeostatic window, comparator 402 may output a positive value for error signal 404, if sensed bioelectric signal 412 is less than the lower threshold of the homeostatic window, comparator 402 may output a negative value for error signal 404, and if sensed bioelectric signal 412 is between the upper and lower thresholds of the homeostatic window, comparator 402 may output a zero value for error signal 404.

[0122] Stimulation generator controller 406 may receive error signal 404 and control operation of stimulation generator 202. For instance, if error signal 404 is positive, based on the absolute value of error signal 404, stimulation generator controller 406 may determine by how much to increase the stimulation intensity of the electrical stimulation (e.g., increase current or voltage amplitude). If error signal 404 is negative, based on the absolute value of error signal 404, stimulation generator controller 406 may determine by how much to decrease the stimulation intensity of the electrical stimulation (e.g., increase current or voltage amplitude). If error signal 404 is zero, stimulation generator controller 406 may not change the stimulation intensity.

[0123] In this way, processing circuitry 210 (e.g., comparator 402) may receive characteristic information of a sensed bioelectric signal 412 (e.g., amplitude of sensed bioelectric signal 412). Processing circuitry 210 (e.g., via stimulation generator controller 406) may adjust delivery of electrical stimulation based on the characteristic information and the adjusted homeostatic window.

[0124] As described, stimulation generator controller 406 may adjust the stimulation intensity of the electrical stimulation that stimulation generator 202 outputs. In some examples, the rate at which the adjustment of the stimulation intensity occurs may be a factor of whether patient 112 is awake or asleep. For instance, if an adjustment to the stimulation intensity is needed, and if patient 112 is awake, stimulation generator controller 406 may ramp up or ramp down the stimulation intensity quicker than if patient 112 is asleep.Docket No.: A0013938W001

[0125] In some examples, stimulation generator controller 406 may control the ramp up or ramp down of the stimulation intensity based on whether patient 112 is awake or asleep. For instance, IMD 106 may include an accelerometer 414 for detecting posture change. Comparator 416 may determine posture change (e.g., if acceleration stayed still for a wake-detection threshold amount of time), stimulation generator controller 406 may increase the rate at which adjustment to stimulation intensity occurs until sleep is again detected. This allows for a faster ramp to therapeutic levels upon waking.

[0126] In some examples, increasing the rate at which adjustment to stimulation intensity occurs may be limited to nighttime and / or may be temporary. For instance, the faster ramp rate may temporary, until patient 112 is back asleep, such as if patient 112 woke to go to restroom, or a certain time has elapsed (e.g., patient 112 is awake for the day).

[0127] Accordingly, in some examples, processing circuitry 210 may be configured to determine that patient 112 transitioned from a sleep state to an awake state (e.g., based on output from comparator 416). Processing circuitry 210 may be further configured to adjust delivery of the electrical stimulation based on the determination that patient 112 transitioned from the sleep state to the awake state by increasing a rate at which the delivery of the electrical stimulation is adjusted (e.g., increase the ramp up rate). Controlling the ramp up or ramp down rate based on whether patient 112 is awake or asleep is one example, and may not be necessary in all examples.

[0128] FIGS. 5A-5E are conceptual diagrams illustrating examples of adjusting a center target of the homeostatic window or a homeostatic window range of the homeostatic window to generate an adjusted homeostatic window of the closed-loop feedback policy for the dual threshold operational mode. FIG. 5A illustrates sensed bioelectric signal 500 over time with an initial homeostatic window. For instance, in FIG. 5A, the initial homeostatic window has a homeostatic window range of 502A. The initial homeostatic window has an upper threshold 506A and lower threshold 506B. Upper limit 504A is the upper limit for the homeostatic window, and lower limit 504B is the lower limit for the homeostatic window. Center target 508 is the center of the initial homeostatic window.

[0129] FIG. 5B illustrates an example of processing circuitry 210, responsive to the treatment level component (e.g., of the request to adjust the closed-loop feedback policy) indicating that IMD 106 is to be biased to deliver higher intensity electrical stimulation, adjusting the center target towards a lower limit of the homeostatic window. For instance, in FIG. 5B, center target 512 is lower than center target 508 of FIG. 5A in the direction of lower limit 504B. This results in the lowering for the upper threshold from upper threshold 506A of FIG. 5A to upper threshold 510A of FIG. 5B, and in the lowering of the lower threshold from lower threshold 506B of FIG.5 A to lower threshold 510B of FIG. 5B. As can be seen in FIG. 5B, more portions of sensedDocket No.: A0013938W001 bioelectric signal 500 is above upper threshold 510A as compared to upper threshold 506A of FIG. 5A. Therefore, sensed bioelectric signal 500 is more likely to be above upper threshold 510A than upper threshold 506 A, triggering more instances of increasing of the stimulation intensity. Accordingly, IMD 106 is more likely to deliver higher intensity electrical stimulation in the example of FIG. 5B as compared to the example of FIG. 5 A. In the example of FIG. 5B, the homeostatic window range 502B (e.g., upper threshold 510A minus lower threshold 510B) may the same as the homeostatic window range 502A of FIG. 5A (e.g., upper threshold 506A minus lower threshold 504B).

[0130] FIG. 5C illustrates an example of processing circuitry 210, responsive to the treatment level component (e.g., of the request to adjust the closed-loop feedback policy) indicating that IMD 106 is to be biased to deliver lower intensity electrical stimulation, adjusting the center target towards a higher limit of the homeostatic window. For instance, in FIG. 5C, center target 516 is higher than center target 508 of FIG. 5A in the direction of upper limit 504A. This results in the raising of the upper threshold from upper threshold 506A of FIG. 5 A to upper threshold 514A of FIG. 5C, and in the raising of the lower threshold from lower threshold 506B of FIG. 5A to lower threshold 514B of FIG. 5C. As can be seen in FIG. 5C, more portions of sensed bioelectric signal 500 is below lower threshold 514B as compared to lower threshold 506B of FIG. 5A. Therefore, sensed bioelectric signal 500 is more likely to be below lower threshold 514B than upper threshold 506B, triggering more instances of decreasing of the stimulation intensity. Accordingly, IMD 106 is more likely to deliver lower intensity electrical stimulation in the example of FIG. 5C as compared to the example of FIG. 5 A. In the example of FIG. 5C, the homeostatic window range 502C (e.g., upper threshold 514A minus lower threshold 514B) may the same as the homeostatic window range 502 A of FIG. 5 A (e.g., upper threshold 506A minus lower threshold 504B).

[0131] FIG. 5D illustrates an example of processing circuitry 210, responsive to the responsiveness level component indicating that IMD 106 is to be biased to adjust the delivery of electrical stimulation more often, decreasing the homeostatic window range. For instance, FIG.5D illustrates homeostatic window range 502D with upper threshold of 518A and lower threshold of 518B. Center target 508 of FIG. 5D may be the same as center target 508 of FIG. 5A.

[0132] In FIG. 5D, small changes in the sensed bioelectric signal can trigger an adjustment to the delivery of electrical stimulation, resulting in more frequent adjustments. For instance, assume that the amplitude of the bioelectric signal is approximately the same as center target 508. In this example, a small variation in the amplitude of the bioelectric signal may cause theDocket No.: A0013938W001 bioelectric signal to be greater than upper threshold 518A or lower threshold 518B, thereby triggering an adjustment to the stimulation intensity more frequently.

[0133] FIG. 5E illustrates an example of processing circuitry 210, responsive to the responsiveness level component indicating that IMD 106 is to be biased to adjust the delivery of electrical stimulation less often, increasing the homeostatic window range. For instance, FIG. 5E illustrates homeostatic window range 502E with upper threshold of 520A and lower threshold of 520B. Center target 508 of FIG. 5E may be the same as center target 508 of FIG. 5A.

[0134] In FIG. 5E, small changes in the sensed bioelectric signal may not trigger an adjustment to the delivery of electrical stimulation, resulting in less frequent adjustments. For instance, assume that the amplitude of the bioelectric signal is approximately the same as center target 508. In this example, a small variation in the amplitude of the bioelectric signal may not cause the bioelectric signal to be greater than upper threshold 520A or lower threshold 520B, thereby triggering an adjustment to the stimulation intensity less frequently. That is, relatively large changes in the sensed bioelectric signal may be needed to trigger an adjustment to the stimulation intensity.

[0135] While FIGS. 5A-5E illustrate example ways in which to adjust the closed-loop feedback policy that defines a homeostatic range, the upper limit 504A and the lower limit 504B may still control how much adjustment is allowed. For instance, to automatically adjust the homeostatic window, processing circuitry 210 may be configured to adjust the homeostatic window such that an upper threshold of the adjusted homeostatic window is less than an upper limit 504A of the upper threshold, and a lower threshold of the adjusted homeostatic window is greater than a lower limit 504B of the lower threshold.

[0136] FIG. 6 is a flow diagram illustrating example techniques of automatically adjusting a closed-loop feedback policy for a single threshold operational mode. As described, in single threshold mode, processing circuitry 210 may adjust a single bioelectric signal threshold. In one or more examples, to automatically adjust the bioelectric signal threshold to generate an adjusted bioelectric signal threshold, processing circuitry 210 may bias IMD 106 to deliver electrical stimulation more often at a first intensity than a second intensity. For instance, in the ST mode, the request to adjust a closed-loop feedback policy may include a boost mode intensity component indicating whether IMD 106 is biased to deliver electrical stimulation more often at the first intensity or the second intensity.

[0137] In ST mode, to achieve a bias of delivering electrical stimulation more often at a higher intensity would result in lowering the bioelectric signal threshold. This way, the bioelectric signal is more likely to be above the bioelectric signal threshold, resulting in higher intensity of the electrical stimulation. To achieve a bias of delivering electrical stimulation moreDocket No.: A0013938W001 often at a lower intensity would result in increasing the bioelectric signal threshold. This way, the bioelectric signal is more likely to be below the bioelectric signal threshold, resulting in lower intensity of the electrical stimulation.

[0138] One example way of defining how often electrical stimulation is delivered at a higher intensity relative to a lower intensity may be defined by a target duty cycle ratio. The target duty cycle ratio, also called target average intensity ratio, may be based on calculations of average electrical stimulation intensity over a first period that are then compared to average thresholds over a second, longer period. For instance, to determine a duty cycle ratio (e.g., average intensity ratio), processing circuitry 210 may determine a plurality of average intensity values of the electrical stimulation delivered by the medical device, each average intensity value being determined over a first period of time (e.g., 10 mins). For instance, processing circuitry 210 may determine a first average intensity value, which is the average of the electrical stimulation intensity for 10 mins, processing circuitry 210 may determine a second average intensity value, which is the average of the electrical stimulation intensity for the next 10 mins, and so on.

[0139] For each of the plurality of average intensity values, processing circuitry 210 may determine whether an average intensity value is greater than a first average intensity threshold or less than a second average intensity threshold. The first average intensity threshold and the second average intensity threshold may also be referred to as a first duty cycle threshold and a second duty cycle threshold. In some examples, the first average intensity threshold and the second average intensity threshold may be the same. In some examples, the first average intensity threshold and the second average intensity threshold may be the same. A user may define the first average intensity threshold and the second average intensity threshold (e.g., with programmer), or the first average intensity threshold and the second average intensity threshold may be preprogrammed.

[0140] As an example, processing circuitry 210 may determine whether a first average intensity value is greater than a first average intensity threshold, less than a second average intensity threshold, or between the first average intensity threshold and the second average intensity threshold. Processing circuitry 210 may determine whether a second average intensity value is greater than a first average intensity threshold, less than a second average intensity threshold, or between the first average intensity threshold and the second average intensity threshold, and so forth. In this manner, processing circuitry 210 may classify each of the average intensity values as greater than first average intensity threshold, less than second average intensity threshold, or in between first average intensity threshold and second average intensity threshold.Docket No.: A0013938W001

[0141] Processing circuitry 210 may determine an average intensity ratio, also called duty cycle ratio, based on a number of the average intensity values that are greater than the first average intensity threshold or (e.g., and / or) a number of the average intensity values that are less than the second average intensity threshold over a second period of time (e.g., 1 day). For example, processing circuitry 210 may determine, over the second period of time (e.g., 1 day), how many average intensity values were classified as being greater than the first average intensity threshold or how many average intensity values were classified as being less than the second average intensity threshold. In one example, processing circuitry 210 may divide the number of average intensity values that were classified as being greater than the first average intensity threshold with the total number of average intensity values that were determined over the second period of time to determine the average intensity ratio. As another example, processing circuitry 210 may divide the number of average intensity values that were classified as being less than the second average intensity threshold with the total number of average intensity values that were determined over the second period of time to determine the average intensity ratio.

[0142] As an illustrative example, in ST mode, when the bioelectric signal is greater than the bioelectric signal threshold, IMD 106 may deliver electrical stimulation at a first intensity, and when the bioelectric signal is less than the bioelectric signal threshold, IMD 106 may deliver electrical stimulation at a second intensity, where the first intensity is greater than the second intensity. Processing circuitry 210 may determine an average of the electrical stimulation intensity (e.g., amplitude) over a first period of time (e.g., 10 minutes). In this example, assume that over that first period of time, IMD 106 delivered electrical stimulation at the first, higher intensity for 70% of the 10 minutes, and at the second, lower intensity for 30% of the 10 minutes. In this example, the duty cycle may be 70%, or conversely as 30%. However, if represented in terms of amplitude (e.g., average electrical stimulation intensity), the average electrical stimulation intensity may be 0.7*(first intensity), or conversely as 0.3*(second intensity).

[0143] For ease, the example techniques are described with respect to the first intensity, but the techniques would be applicable relative to the second intensity as well. In this example, a first average intensity value may be 0.7*(first intensity). Processing circuitry 210 may repeat these steps for the next 10 minutes to determine a second average intensity value, and so forth to determine a plurality of average intensity values of the electrical stimulation.

[0144] Assume that the first average intensity threshold is 0.6*(first intensity) and the second average intensity threshold is 0.4*(first intensity). For each of the plurality of average intensity values, processing circuitry 210 may determine whether an average intensity value is greater than a first average intensity threshold or less than a second average intensity threshold. In this case,Docket No.: A0013938W001 the first average intensity value would be classified as being greater than the first average intensity threshold. Processing circuitry 210 may repeat these steps for each of the plurality of average intensity values classifying each of the average intensity values as high if greater than first average intensity threshold, low if less than second average intensity threshold, or between if between the first and second average intensity thresholds.

[0145] For a second period of time (e.g., day or more), processing circuitry 210 may determine a cumulative time spent “high” (e.g., number of average intensity values greater than the first average intensity threshold) divided by the cumulative time spent “low” (e.g., number of average intensity values less than the second average intensity threshold), which is one example of the duty cycle ratio, also called average intensity ratio. As another example, processing circuitry 210 may determine the average intensity ratio as the number of average intensity values greater than the first average intensity threshold divided by the total number of average intensity values.

[0146] In one or more examples, the request to adjust the closed-loop feedback policy may indicate a target average intensity ratio. As described in more detail, processing circuitry 210 may repeatedly adjust the bioelectric signal threshold causing a change in the average intensity ratio until the average intensity ratio is approximately equal to the target average intensity ratio defined by the request to adjust the closed-loop feedback policy. That is, target average intensity ratio may be driven by the “boost intensity” component, which in turn drives necessary changes in the bioelectric threshold so that actual average intensity ratio is approximately equal to the target average intensity ratio.

[0147] For instance, in the example of FIG. 6, assume that stimulation generator 202 is configured to deliver electrical stimulation at a first intensity (e.g., first amplitude) when the bioelectric signal is greater than the bioelectric signal threshold, and at a second intensity (e.g., second amplitude) when the bioelectric signal is less than the bioelectric signal threshold.Stimulation generator controller 608 may output information to average intensity ratio calculator 606 the plurality of average intensity values. For instance, stimulation generator controller 608 may output a first average intensity value after 10 minutes indicative of the average of the stimulation intensity over the 10 minutes, a second average intensity value after the next 10 minutes indicative of the average of the stimulation intensity over the next 10 minutes, and so forth. In this example, a first period of time is 10 minutes, but other time durations for the first period of time are possible such as 10 seconds, 30 seconds, 1 minute, 5 minute, 15 minutes, and so forth.

[0148] Average intensity ratio calculator 606 may also receive a first average intensity threshold and a second average intensity threshold. If the first average intensity threshold and theDocket No.: A0013938W001 second average intensity threshold are the same, average intensity ratio calculator 606 may receive one average intensity threshold. The user may provide the first and second average intensity thresholds, or the first and second average intensity thresholds may be preset.

[0149] Average intensity ratio calculator 606 may, for each of the plurality of average intensity values, determine whether an average intensity value is greater than the first average intensity threshold or less than the second average intensity threshold. Average intensity ratio calculator 606 may determine an average intensity ratio based on a number of the average intensity values that are greater than the first average intensity threshold or a number of the average intensity values that are less than the second average intensity threshold over a second period of time (e.g., one day). The second period of time being one day is provided as one example, but other time durations for the second period of time are possible such as 1 hour, 12 hours, 36 hours, and so forth.

[0150] As one example, average intensity ratio calculator 606 may divide the number of average intensity values that where greater than the first average intensity threshold by the number of average intensity values that where less than the second average intensity threshold, or vice versa to determine the average intensity ratio. As another example, average intensity ratio calculator 606 may divide the number of average intensity values that where greater than the first average intensity threshold by the total number of average intensity values to determine the average intensity ratio. As another example, average intensity ratio calculator 606 may divide the number of average intensity values that where less than the second average intensity threshold by the total number of average intensity values to determine the average intensity ratio.

[0151] Comparator 604 may compare the average intensity ratio to a target average intensity ratio defined by the request. The target average intensity ratio defined by the request may indicate whether IMD 106 is to deliver electrical stimulation more often at the first intensity or the second intensity. If the average intensity ratio is different than the target average intensity ratio, comparator 604 may output an error signal to threshold controller 602. Threshold controller 602 may then adjust the bioelectric signal threshold. This may be a first adjusted bioelectric signal threshold.

[0152] Comparator 600 may receive the first adjusted bioelectric signal threshold from threshold controller 602, and receive sensed bioelectric signal 616 from bioelectric sensor 610. Bioelectric sensor 610 may be part of sensing module 202. For instance, bioelectric sensor 610 may receive bioelectric signals (e.g., LFP signals) 614 from patient 112. Bioelectric sensor 610 may sample the bioelectric signals 614 at a particular sampling rate (e.g., 1-50 Hz, such as 20 Hz), and the output may be sensed bioelectric signal 616.Docket No.: A0013938W001

[0153] Comparator 600 may compare the sensed bioelectric signal 616 to the first adjusted bioelectric signal threshold, and the result may be error signal 618. For example, if sensed bioelectric signal 616 is greater than the first adjusted bioelectric signal threshold, comparator 600 may output a positive value for error signal 618, and if sensed bioelectric signal 616 is less than the first adjusted bioelectric signal threshold, comparator 600 may output a negative value for error signal 618.

[0154] Stimulation generator controller 608 may receive error signal 618 and control operation of stimulation generator 202. For instance, if error signal 618 is positive, based on the absolute value of error signal 618, stimulation generator controller 608 may determine by how much to increase the stimulation intensity of the electrical stimulation (e.g., increase current or voltage amplitude). If error signal 618 is negative, based on the absolute value of error signal 618, stimulation generator controller 608 may determine by how much to decrease the stimulation intensity of the electrical stimulation (e.g., increase current or voltage amplitude).

[0155] In this way, processing circuitry 210 (e.g., comparator 600) may receive characteristic information of a sensed bioelectric signal 616 (e.g., amplitude of sensed bioelectric signal 616). Processing circuitry 210 (e.g., via stimulation generator controller 608) may adjust delivery of electrical stimulation based on the characteristic information and the adjusted bioelectric signal threshold.

[0156] Because the first adjusted bioelectric signal threshold is different than the original bioelectric signal threshold, the plurality of average intensity values of the electrical stimulation delivered by IMD 106 will change. For instance, assume that threshold controller 602 increased the original bioelectric signal threshold to the generate the first adjusted bioelectric signal threshold. In this case, there would be fewer instances where the amplitude of the bioelectric signal will be greater than the first adjusted bioelectric signal threshold because the bioelectric signal threshold was raised from the original bioelectric signal threshold. Therefore, over the first period of time (e.g., 10 minutes) there would be fewer instances where IMD 106 delivers electrical stimulation at the first intensity, which means that there will be fewer average intensity values that are greater than the first average intensity. This in turn would mean that average intensity ratio will lower.

[0157] Comparator 604 would then compare this new lower average intensity ratio to the target average intensity ratio, and generate a new error signal. Threshold controller 602 may then adjust the first adjusted bioelectric signal threshold to generate a second adjust bioelectric signal threshold. This process will keep repeating until over time the adjusted bioelectrical signal threshold is such that the average intensity ratio is approximately equal to the target average intensity ratio. That is, based on the comparison by comparator 604, threshold controller 602Docket No.: A0013938W001 may repeatedly adjust the bioelectric signal threshold causing a change in the average intensity ratio until the average intensity ratio is approximately equal to the target average intensity ratio defined by the request to adjust the closed-loop feedback policy.

[0158] This process may take multiple days, but in the end the adjusted bioelectric signal threshold may bias IMD 106 to deliver electrical stimulation more often at a first intensity than a second intensity. That is, the adjusted bioelectric signal threshold causes IMD 106 to deliver the electrical stimulation more often at the first intensity than the second intensity. For instance, from the perspective of IMD 106, from the request to adjust the closed-loop feedback policy, processing circuitry 210 may determine the target average intensity ratio. For instance, if the user desires IMD 106 to be biased to deliver electrical stimulation at the first intensity (e.g., more likely to deliver electrical stimulation at the first intensity than the second intensity), processing circuitry 210 may determine the target average intensity ratio such that over time the bioelectric signal threshold is adjusted (e.g., lowered) such that IMD 106 is more likely to deliver electrical stimulation at the first intensity because the bioelectric signal is more likely be exceed the adjusted bioelectric signal threshold than the original bioelectric signal threshold.

[0159] With the target average intensity ratio in place, the combined processes of average intensity ratio calculator 606, comparator 604, and threshold controller 602 may repeatedly adjust the bioelectric signal threshold causing a change in the average intensity ratio until the average intensity ratio is approximately equal to the target average intensity ratio defined by the request to adjust the closed-loop feedback policy. In this example, the adjusted bioelectric signal threshold causes the medical device to deliver the electrical stimulation more often at the first intensity than the second intensity.

[0160] FIG. 7A is a conceptual diagram illustrating an example of an averaged bioelectric signal with a bioelectric signal threshold. FIG. 7B is a conceptual diagram illustrating an example of an average intensity of electrical stimulation delivered over a period of time and average intensity thresholds. FIG. 7C is a conceptual diagram illustrating an example of a bioelectric signal. FIG. 7D is a conceptual diagram illustrating an example of changes to electrical stimulation intensity.

[0161] For instance, FIG. 7A illustrates bioelectric signal 700 and an example of bioelectric signal threshold 702. In FIG. 7A, the average intensity value may be relatively low for duration 704A, relatively high for duration 704B, relatively low for duration 704C, relatively high for duration 704D, and relatively low for duration 704E. FIG. 7B illustrates graph 706 of a plurality of average intensity values. For example, FIG. 7B illustrate average intensity value 708A, average intensity value 708B, and average intensity value 708C on graph 706 as illustrative examples.Docket No.: A0013938W001

[0162] FIGS. 7C and 7D illustrate an example way in which average intensity value 708A, average intensity value 708B, and average intensity value 708C may be determined. FIGS. 7C and 7D are not to scale. FIG. 7C illustrates sensed bioelectric signal 712, which may be the bioelectric signal sampled in range of 1-50 Hz, such as 20 Hz. FIG. 7C also illustrates bioelectric signal threshold 714.

[0163] In this example, if the characteristic (e.g., amplitude) of sensed bioelectric signal 712 is greater than bioelectric signal threshold 714, IMD 106 delivers electrical stimulation at first intensity 716A (e.g., current amplitude of 716A), as illustrated in FIG. 7D. If the characteristic (e.g., amplitude) of sensed bioelectric signal 712 is less than bioelectric signal threshold 714, IMD 106 delivers electrical stimulation at second intensity 716B (e.g., current amplitude of 716B), as illustrated in FIG. 7D. Over a first period of time (e.g., 10 minutes), processing circuitry 210 may determine an average intensity value indicating on average what the stimulation intensity was during that period of time (e.g., total time stimulation intensity was at first intensity 716A divided total time of the first period of time, as one example).

[0164] As can be seen in FIG. 7D, the stimulation intensity is more often at the first intensity 716A then at the second intensity 716B. Therefore, the average intensity value calculated from the example of FIG. 7D may be average intensity value 708B of FIG. 7B. Average intensity values 708A and 708C may be calculated in the same way, but at different periods of time where the stimulation intensity may be more often at the second intensity 716B then the first intensity 716A.

[0165] FIG. 7B illustrates first average intensity threshold 710A and second average intensity threshold 710B. As can be seen, processing circuitry 210 may classify average intensity value 708 A as being between first average intensity threshold 710A and second average intensity threshold 710B. Processing circuitry 210 may classify average intensity value 708B as being greater than first average intensity threshold 710A, and classify average intensity value 708C as being less than second average intensity threshold 710B.

[0166] Processing circuitry 210 may determine an average intensity ratio based on a number of the average intensity values that are greater than the first average intensity threshold or a number of the average intensity values that are less than the second average intensity threshold over a second period of time, and compare the average intensity ratio to a target average intensity ratio defined by the request, the target average intensity ratio defined by the request indicating whether the medical device is to deliver electrical stimulation more often at the first intensity or the second intensity. Processing circuitry 210, based on the comparison, may repeatedly adjust the bioelectric signal threshold causing a change in the average intensity ratio until the averageDocket No.: A0013938W001 intensity ratio is approximately equal to the target average intensity ratio defined by the request to adjust the closed-loop feedback policy.

[0167] FIG. 8 is a conceptual diagram illustrating example of changing intensity levels for single threshold operational mode. In some examples, the first intensity is higher than the second intensity, and processing circuitry 210 may be further configured to cause IMD 106 to deliver the electrical stimulation toggling between the first intensity and the second intensity, and transition to delivering electrical stimulation toggling between the first intensity and an intensity that is lower than the second intensity. This may be available in ST mode.

[0168] For instance, in FIG. 8, if the sensed bioelectric signal is greater than the bioelectric signal threshold, IMD 106 may deliver electrical stimulation having first intensity 800, and if the sensed bioelectric signal is less than the bioelectric signal threshold, IMD 106 may deliver electrical stimulation having second intensity 802A. The first intensity 800 is higher than the second intensity 802A. In some examples, the first intensity 800 is at or near a maximum intensity at which IMD 106 is to deliver the electrical stimulation.

[0169] Over time, IMD 106 may lower the intensity of the electrical stimulation when the bioelectric signal is less than the bioelectric signal threshold. After some time, if the sensed bioelectric signal is greater than the bioelectric signal threshold, IMD 106 may deliver electrical stimulation having first intensity 800, and if the sensed bioelectric signal is less than the bioelectric signal threshold, IMD 106 may deliver electrical stimulation having third intensity 802B. IMD 106 may keep repeating this over time.

[0170] After some more time, if the sensed bioelectric signal is greater than the bioelectric signal threshold, IMD 106 may deliver electrical stimulation having first intensity 800, and if the sensed bioelectric signal is less than the bioelectric signal threshold, IMD 106 may deliver electrical stimulation having fourth intensity 802C. After some more time, if the sensed bioelectric signal is greater than the bioelectric signal threshold, IMD 106 may deliver electrical stimulation having first intensity 800, and if the sensed bioelectric signal is less than the bioelectric signal threshold, IMD 106 may deliver electrical stimulation having fifth intensity 802D.

[0171] The example of FIG. 8 may be referred to as ST limit-setting. For instance, when patient 112 is off medication, stimulation intensity is increased to desired upper limit of 800. While delivering ST, the lower limit is slowly decreased (e.g., from 802A, to 802B, to 802C, and then to 802D) by the user until side-effects introduced by the upper limit of 800 are mitigated. There may be balancing of the lower limit between side effect mitigation and adjusting ramp up time to avoid ramp side effects (e.g. paresthesia). For instance, lowering the lower intensity (e.g., 802A, to 802B, to 802C, and then to 802D) may improve side effects from the relatively higherDocket No.: A0013938W001 stimulation intensity at stimulation intensity 800, but may not be lowered to too much because of the time taken to ramp up the stimulation intensity.

[0172] FIG. 9 is a flow diagram illustrating example techniques of selecting between operational modes. FIG. 9 illustrates as example of processing circuitry 210 automatically determining whether IMD 106 is to operate in DT mode or ST mode. For FIG. 9, the manner in which the homeostatic window for DT or the bioelectric signal threshold for ST are determined may be based on the above techniques or based on any other technique.

[0173] Mode select unit 900 may receive as input information indicative of the stimulation intensity of the electrical stimulation that stimulation generator 202 is outputting. Based on the stimulation intensity, mode select unit 900 may select between DT mode (e.g., homeostatic window) or ST mode (e.g. bioelectric signal threshold). Comparator 902 may receive the homeostatic window or the bioelectric signal threshold from mode select unit 900.

[0174] Bioelectric sensor 906, which may be part of sensing module 202, may receive bioelectric signal 908, and output first sensed bioelectric signal 910 (e.g., sampled bioelectric signal 908 at sample rate of 1-50 Hz, such as 5 Hz) and / or second sensed bioelectric signal 912 (e.g., sampled bioelectric signal 908 at sample rate of 1-50 Hz, such as 20 Hz). If DT mode is selected, comparator 902 may compare sensed bioelectric signal 910 to the homeostatic window. If ST mode is selected, comparator 902 may compare sensed bioelectric signal 912 to the bioelectric signal threshold.

[0175] Comparator 902 may output an error signal that control stimulation generator controller 902. For instance, if DT mode is selected, stimulation generator controller 904 may operate similar to stimulation generator controller 406 (FIG. 4). If ST mode is selected, stimulation generator controller 902 may operate similar to stimulation generator controller 608 (FIG. 6).

[0176] In one or more examples, when the stimulation intensity is relatively low, processing circuitry 210 may select DT mode, but as the stimulation intensity increases, processing circuitry 210 may switch to ST mode. For example, processing circuitry 210 may compare the stimulation intensity to a stimulation intensity threshold. To select the operation mode, processing circuitry 210 may select the dual threshold mode based on the stimulation intensity being less than the stimulation intensity threshold. In some examples, to select the operation mode, processing circuitry 210 may select the single threshold mode based on the stimulation intensity being greater than the stimulation intensity threshold.

[0177] Once in ST mode, processing circuitry 210 may remain in ST mode until the amount of time that processing circuitry 210 is delivery electrical stimulation at the lower intensity is greater than a threshold, and then transition to DT mode. For example, processing circuitry 210Docket No.: A0013938W001 may, while causing IMD 106 to operate in the single threshold mode, determine at least one of a first amount of time that IMD 106 is delivering the electrical stimulation at a first stimulation intensity or a second amount of time that IMD 106 is delivering the electrical stimulation at a second stimulation intensity, the second stimulation intensity being lower than the first stimulation intensity. Processing circuitry 210 may determine whether to transition IMD 106 from the single threshold (ST) mode to the dual threshold (DT) mode based on at least one of the first amount of time or the second amount of time. For instance, processing circuitry 210 may determine a duty cycle based on at least one of the first amount of time and a period of time or the second amount of time and the period of time, compare the duty cycle to a duty cycle threshold, and determine whether to transition (e.g., from the ST mode back to the DT mode) based on the comparison.

[0178] In some examples, the ST mode starts with very tight stimulation limits, and widens to its target width. Upon transitioning back from ST mode to DT mode, the opposite occurs where the stimulation intensity tightens back towards a single amplitude.

[0179] FIG. 10 is a conceptual diagram illustrating example of stimulation intensity for selecting between operation modes. Initially, IMD 106 may be in the DT mode 1002 A. As the stimulation intensity increases, as illustrated by stimulation intensity 1000, the stimulation intensity may increase until reaching a stimulation intensity threshold. In FIG. 10, while operating the DT mode, the stimulation intensity may keep rising if the sensed bioelectric signal remains greater than the upper threshold of the homeostatic window.

[0180] After crossing the stimulation intensity threshold, IMD 106 may transition to the ST mode. In the ST mode, IMD 106 may deliver electrical stimulation with stimulation intensity of 1004B if the sensed bioelectric signal is greater than the bioelectric signal threshold. IMD 106 may deliver electrical stimulation with stimulation intensity of 1004 A if the sensed bioelectric signal is less than the bioelectric signal threshold. IMD 106 may remain in ST mode until the amount of time that IMD 106 delivers electrical stimulation with stimulation intensity of 1004 A goes above a threshold. For instance, processing circuitry 210 may determine a duty cycle based on a duty cycle of delivery of electrical stimulation with stimulation intensity of 1004 A, and compare the duty cycle to a duty cycle threshold. If the duty cycle is greater than the duty cycle threshold, which means that stimulation intensity is at stimulation intensity 1004A more often than at stimulation intensity 1004B by a threshold amount, processing circuitry 210 may transition IMD 106 back to the DT mode.

[0181] In general, DT mode may function well when the stimulation intensity is relatively low, and ST mode may function well when the stimulation intensity is approaching an intensity limit. For instance, in FIG. 10, stimulation intensity 1004 A may a minimum ST mode limit, andDocket No.: A0013938W001 stimulation intensity 1004B may be a maximum ST mode limit, and in some cases, nearing the maximum that IMD 106 can deliver.

[0182] FIG. 11 is a flowchart illustrating an example method of operation for adjusting a closed-loop feedback policy for a dual threshold operational mode. For ease, the example techniques are described with respect to processing circuitry 210.

[0183] Processing circuitry 210 may receive a request to adjust a closed-loop feedback policy, the closed-loop feedback policy defining a homeostatic window for a bioelectric signal (1100). The therapy adjustment request may be received from a clinician programmer or a patient programmer (e.g., programmer 104). In some examples, the request does not define a center target or a homeostatic window range of a homeostatic window. The request may include a treatment level component indicating whether the medical device is to be biased to deliver higher intensity electrical stimulation or lower intensity electrical stimulation more often, or a responsiveness level component indicating whether the medical device is to be biased to adjust the delivery of electrical stimulation more often or less often.

[0184] Responsive to receiving the request, processing circuitry 210 may automatically adjust at least one of a center target of the homeostatic window or a homeostatic window range of the homeostatic window to generate an adjusted homeostatic window (1102). For example, to automatically adjust the center target, processing circuitry 210 may be configured to, responsive to the treatment level component indicating that the medical device is to be biased to deliver higher intensity electrical stimulation, adjust the center target towards a lower limit of the homeostatic window. As another example, to automatically adjust the center target, processing circuitry 210 may be configured to, responsive to the treatment level component indicating that the medical device is to be biased to deliver lower intensity electrical stimulation, adjust the center target towards a higher limit of the homeostatic window.

[0185] As another example, to automatically adjust the homeostatic window range, processing circuitry 210 may be configured to, responsive to the responsiveness level component indicating that the medical device is to be biased to adjust the delivery of electrical stimulation more often, decrease the homeostatic window range. As another example, to automatically adjust the homeostatic window range, processing circuitry 210 may be configured to, responsive to the responsiveness level component indicating that the medical device is to be biased to adjust the delivery of electrical stimulation less often, increase the homeostatic window range.

[0186] In some examples, to automatically adjust the homeostatic window, processing circuitry 210 may be configured to adjust the homeostatic window such that an upper threshold of the adjusted homeostatic window is less than an upper limit of the upper threshold, and aDocket No.: A0013938W001 lower threshold of the adjusted homeostatic window is greater than a lower limit of the lower threshold. At least one of the upper limit and the lower limit may be based on patient feedback.

[0187] Processing circuitry 210 may receive characteristic information of a sensed bioelectric signal (e.g., amplitude of the sensed bioelectric signal) (1104). The sensed bioelectric signal may be a local field potential (LFP) signal sensed within a brain of a patient, and the medical device is implanted within the patient. In some examples, the LFP signal is sampled at a sampling rate of less than or equal to 5 Hz (e.g., in range of 1-50 Hz) to generate the sensed bioelectric signal.

[0188] Processing circuitry 210 may adjust delivery of electrical stimulation based on the characteristic information and the adjusted homeostatic window (1106). The electrical stimulation may be delivered to a brain of a patient, and the medical device may be implanted within the patient. For instance, if the amplitude of the sensed bioelectric signal is greater than the upper threshold of the adjusted homeostatic window, processing circuitry 210 may increase the stimulation intensity. If the amplitude of the sensed bioelectric signal is less than the lower threshold of the adjusted homeostatic window, processing circuitry 210 may decrease the stimulation intensity. In some example, processing circuitry 210 may be configured to determine that the patient transitioned from a sleep state to an awake state. Processing circuitry 210 may be further configured to adjust delivery of the electrical stimulation based on the determination that the patient transitioned from the sleep state to the awake state by increasing a rate at which the delivery of the electrical stimulation is adjusted.

[0189] FIG. 12 is a flowchart illustrating an example method of operation for adjusting a closed-loop feedback policy for a single threshold operational mode. For ease, the example techniques are described with respect to processing circuitry 210.

[0190] Processing circuitry 210 may receive a request to adjust a closed-loop feedback policy, the closed-loop feedback policy defining a bioelectric signal threshold for a bioelectric signal (1200). The request may not define the adjusted bioelectric signal threshold. Rather, the request may include a boost mode intensity component indicating whether the medical device is biased to deliver electrical stimulation more often at the first intensity or the second intensity. Similar to FIG. 11, the therapy adjustment request may be received from a clinician programmer or a patient programmer (e.g., programmer 104).

[0191] Responsive to the request, processing circuitry 210 may automatically adjust the bioelectric signal threshold to generate an adjusted bioelectric signal threshold by biasing the medical device to deliver electrical stimulation more often at a first intensity than a second intensity (1202). For example, to generate the adjusted bioelectric signal threshold, the processing circuitry 210 may be configured to determine a plurality of average intensity values of the electrical stimulation delivered by IMD 106, each average intensity value being determinedDocket No.: A0013938W001 over a first period of time (e.g., 10 minutes). For each of the plurality of average intensity values, processing circuitry 210 may determine whether an average intensity value is greater than a first average intensity threshold or less than a second average intensity threshold. Processing circuitry 210 may determine an average intensity ratio based on a number of the average intensity values that are greater than the first average intensity threshold or a number of the average intensity values that are less than the second average intensity threshold over a second period of time. Processing circuitry 210 may compare the average intensity ratio to a target average intensity ratio defined by the request, the target average intensity ratio defined by the request indicating whether IMD 106 is to deliver electrical stimulation more often at the first intensity or the second intensity. Based on the comparison, processing circuitry 210 may repeatedly adjust the bioelectric signal threshold causing a change in the average intensity ratio until the average intensity ratio is approximately equal to the target average intensity ratio defined by the request to adjust the closed-loop feedback policy. The adjusted bioelectric signal threshold may cause IMD 106 to deliver the electrical stimulation more often at the first intensity than the second intensity.

[0192] Processing circuitry 210 may receive characteristic information of a sensed bioelectric signal (e.g., amplitude of the sensed bioelectric signal) (1204). Similar to above, the sensed bioelectric signal may be a local field potential (LFP) signal sensed within a brain of a patient, and the medical device is implanted within the patient. For ST mode, the LFP signal may be sampled at a sampling rate in range of 1-50 Hz, such as 20 Hz, and different than the DT mode.

[0193] Processing circuitry 210 may adjust delivery of electrical stimulation based on the characteristic information and the adjusted bioelectric signal threshold (1206). For example, if the amplitude of the bioelectric signal is greater than the adjusted bioelectric signal threshold, processing circuitry 210 may increase a stimulation intensity. If the amplitude of the bioelectric signal is less than the adjusted bioelectric signal threshold, processing circuitry 210 may decrease a stimulation intensity.

[0194] In some examples, the first intensity is higher than the second intensity. Processing circuitry 210 may be further configured to cause the medical device to deliver the electrical stimulation toggling between the first intensity and the second intensity, and transition to delivering electrical stimulation toggling between the first intensity and an intensity that is lower than the second intensity, as illustrated in FIG. 8. The first intensity may be higher than the second intensity, and the first intensity is at or near a maximum intensity at which the medical device is to deliver the electrical stimulation.

[0195] FIG. 13 is a flowchart illustrating an example method of selecting an operational mode. For ease, the example techniques are described with respect to processing circuitry 210.Docket No.: A0013938W001

[0196] Processing circuitry 210 may determine a stimulation intensity at which the medical device is delivering electrical stimulation (1300). For instance, processing circuitry 210 may monitor the signal output to stimulation generator 202 or monitor the output of stimulation generator 202 to determine a stimulation intensity at which the medical device is delivering electrical stimulation.

[0197] Based on the stimulation intensity, processing circuitry 210 may select an operation mode as one of a dual threshold mode or a single threshold mode (1302). In the dual threshold mode, the medical device determines adjustment to delivery of electrical stimulation based on characteristics of a first sensed bioelectric signal being outside an upper threshold and a lower threshold of the dual threshold mode. In the single threshold mode, the medical device determines adjustment to delivery of the electrical stimulation based on characteristics of a second sensed bioelectric signal being greater than or less than a single bioelectric signal threshold. The first sensed bioelectric signal may be a local field potential (LFP) signal sensed within a brain of the patient and sampled at a sampling rate of less than or equal to 5 Hz (e.g., in range of 1-50 Hz), and the second sensed bioelectric signal may be the LFP signal sampled at a sampling rate of less than or equal to 20 Hz (e.g., in range of 1-50 Hz).

[0198] In some examples, processing circuitry 210 may compare the stimulation intensity to a stimulation intensity threshold. To select the operation mode, processing circuitry 210 may be configured to select the dual threshold mode based on the stimulation intensity being less than the stimulation intensity threshold. To select the operation mode, processing circuitry 210 may be configured to select the single threshold mode based on the stimulation intensity being greater than the stimulation intensity threshold.

[0199] Processing circuitry 210 may cause the medical device to operate in the selected operation mode (1306). For instance, processing circuitry 210 may start operating in DT mode, and then if the stimulation intensity (e.g., amplitude of current or voltage of the electrical stimulation) exceeds a stimulation intensity threshold, processing circuitry 210 may cause IMD 106 to operate in the ST mode. While causing the medical device to operate in the single threshold mode, processing circuitry 210 may determine at least one of a first amount of time that the medical device is delivering the electrical stimulation at a first stimulation intensity or a second amount of time that the medical device is delivering the electrical stimulation at a second stimulation intensity, the second stimulation intensity being lower than the first stimulation intensity. Processing circuitry 210 may determine whether to transition the medical device from the single threshold mode to the dual threshold mode based on at least one of the first amount of time or the second amount of time.Docket No.: A0013938W001

[0200] For example, processing circuitry 210 may determine a duty cycle based on at least one of the first amount of time and a period of time or the second amount of time and the period of time. Processing circuitry 210 may compare the duty cycle to a duty cycle threshold, and determine whether to transition based on the comparison. For instance, if the duty cycle is less than the duty cycle threshold, processing circuitry 210 may cause the medical device to transition back to dual threshold mode.

[0201] The following examples are described herein.

[0202] Example 1 A. A medical device comprising: one or more memories; and processing circuitry coupled to the one or more memories, wherein the processing circuitry is configured to: receive a request to adjust a closed-loop feedback policy, the closed-loop feedback policy defining a homeostatic window for a bioelectric signal; responsive to receiving the request, automatically adjust at least one of a center target of the homeostatic window or a homeostatic window range of the homeostatic window to generate an adjusted homeostatic window; receive characteristic information of a sensed bioelectric signal; and adjust delivery of electrical stimulation based on the characteristic information and the adjusted homeostatic window.

[0203] Example 2 A. The medical device of example 1 A, wherein the request does not define the center target or the homeostatic window range.

[0204] Example 3A. The medical device of any of examples 1 A and 2A, wherein the request comprises at least one of: a treatment level component indicating whether the medical device is to be biased to deliver higher intensity electrical stimulation or lower intensity electrical stimulation more often; or a responsiveness level component indicating whether the medical device is to be biased to adjust the delivery of electrical stimulation more often or less often.

[0205] Example 4A. The medical device of example 3 A, wherein to automatically adjust the center target, the processing circuitry is configured to, responsive to the treatment level component indicating that the medical device is to be biased to deliver higher intensity electrical stimulation, adjust the center target towards a lower limit of the homeostatic window.

[0206] Example 5A. The medical device of example 3 A, wherein to automatically adjust the center target, the processing circuitry is configured to, responsive to the treatment level component indicating that the medical device is to be biased to deliver lower intensity electrical stimulation, adjust the center target towards a higher limit of the homeostatic window.

[0207] Example 6A. The medical device of any of examples 3 A-5A, wherein to automatically adjust the homeostatic window range, the processing circuitry is configured to, responsive to the responsiveness level component indicating that the medical device is to beDocket No.: A0013938W001 biased to adjust the delivery of electrical stimulation more often, decrease the homeostatic window range.

[0208] Example 7A. The medical device of any of examples 3 A-5A, wherein to automatically adjust the homeostatic window range, the processing circuitry is configured to, responsive to the responsiveness level component indicating that the medical device is to be biased to adjust the delivery of electrical stimulation less often, increase the homeostatic window range.

[0209] Example 8 A. The medical device of any of examples 1 A-7A, wherein to automatically adjust the homeostatic window, the processing circuitry is configured to adjust the homeostatic window such that an upper threshold of the adjusted homeostatic window is less than an upper limit of the upper threshold, and a lower threshold of the adjusted homeostatic window is greater than a lower limit of the lower threshold.

[0210] Example 9A. The medical device of any of examples 1 A-8A, wherein the medical device is implanted within a patient, wherein the processing circuitry is configured to determine that the patient transitioned from a sleep state to an awake state, wherein the processing circuitry is further configured to adjust delivery of the electrical stimulation based on the determination that the patient transitioned from the sleep state to the awake state by increasing a rate at which the delivery of the electrical stimulation is adjusted.

[0211] Example 10A. The medical device of any of examples 1A-9A, wherein the sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of a patient, and wherein the medical device is implanted within the patient.

[0212] Example 11 A. The medical device of example 10A, wherein the LFP signal is sampled at a sampling rate in range of 1-50 Hz.

[0213] Example 12A. The medical device of any of examples 1 A-l 1 A, wherein the electrical stimulation is delivered to a brain of a patient, and wherein the medical device is implanted within the patient.

[0214] Example 13A. The medical device of any of examples 1 A-12A, wherein the therapy adjustment request is received from a clinician programmer or a patient programmer.

[0215] Example 14A. A method for delivery of electrical stimulation, the method comprising: receiving, with processing circuitry of a medical device, a request to adjust a closed-loop feedback policy, the closed-loop feedback policy defining a homeostatic window for a bioelectric signal; responsive to receiving the request, automatically adjusting, with the processing circuitry, at least one of a center target of the homeostatic window or a homeostatic window range of the homeostatic window to generate an adjusted homeostatic window; receiving, with the processing circuitry, characteristic information of a sensed bioelectric signal;Docket No.: A0013938W001 and adjusting, with the processing circuitry, delivery of electrical stimulation based on the characteristic information and the adjusted homeostatic window.

[0216] Example 15 A. The method of example 14A, wherein the request does not define the center target or the homeostatic window range.

[0217] Example 16A. The method of any of examples 14A and 15A, wherein the request comprises at least one of: a treatment level component indicating whether the medical device is to be biased to deliver higher intensity electrical stimulation or lower intensity electrical stimulation more often; or a responsiveness level component indicating whether the medical device is to be biased to adjust the delivery of electrical stimulation more often or less often.

[0218] Example 17A. The method of example 16A, wherein automatically adjusting the center target comprises responsive to the treatment level component indicating that the medical device is to be biased to deliver higher intensity electrical stimulation, adjusting the center target towards a lower limit of the homeostatic window.

[0219] Example 18 A. The method of example 16A, wherein automatically adjusting the center target comprises responsive to the treatment level component indicating that the medical device is to be biased to deliver lower intensity electrical stimulation, adjusting the center target towards a higher limit of the homeostatic window.

[0220] Example 19A. The method of any of examples 16A-18A, wherein automatically adjusting the homeostatic window range comprises responsive to the responsiveness level component indicating that the medical device is to be biased to adjust the delivery of electrical stimulation more often, decreasing the homeostatic window range.

[0221] Example 20A. The method of any of examples 16A-18A, wherein automatically adjusting the homeostatic window range comprises responsive to the responsiveness level component indicating that the medical device is to be biased to adjust the delivery of electrical stimulation less often, increasing the homeostatic window range.

[0222] Example 21 A. The method of any of examples 14A-20A, wherein automatically adjusting the homeostatic window comprises adjusting the homeostatic window such that an upper threshold of the adjusted homeostatic window is less than an upper limit of the upper threshold, and a lower threshold of the adjusted homeostatic window is greater than a lower limit of the lower threshold.

[0223] Example 22 A. The method of any of examples 14A-21A, wherein the medical device is implanted within a patient, the method further comprising determining that the patient transitioned from a sleep state to an awake state, wherein adjusting comprises adjusting delivery of the electrical stimulation based on the determination that the patient transitioned from theDocket No.: A0013938W001 sleep state to the awake state by increasing a rate at which the delivery of the electrical stimulation is adjusted.

[0224] Example 23 A. The method any of examples 14A-22A, wherein the sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of a patient, and wherein the medical device is implanted within the patient.

[0225] Example 24A. The method of example 23 A, wherein the LFP signal is sampled at a sampling rate in range of 1-50 Hz.

[0226] Example 25 A. The method of any of examples 14A-24A, wherein the electrical stimulation is delivered to a brain of a patient, and wherein the medical device is implanted within the patient.

[0227] Example 26 A. The method of any of examples 14A-25A, wherein the therapy adjustment request is received from a clinician programmer or a patient programmer.

[0228] Example 27A. A computer-readable storage medium comprising instructions that when executed cause one or more processors to perform the method of any of examples 14A-26A.

[0229] Example 28A. A medical device comprising means for performing the method of any of examples 14A-26A.

[0230] Example IB. A medical device comprising: one or more memories; and processing circuitry coupled to the one or more memories, wherein the processing circuitry is configured to: receive a request to adjust a closed-loop feedback policy, the closed-loop feedback policy defining a bioelectric signal threshold for a bioelectric signal; responsive to the request, automatically adjust the bioelectric signal threshold to generate an adjusted bioelectric signal threshold by biasing the medical device to deliver electrical stimulation more often at a first intensity than a second intensity; receive characteristic information of a sensed bioelectric signal; and adjust delivery of electrical stimulation based on the characteristic information and the adjusted bioelectric signal threshold.

[0231] Example 2B. The medical device of example IB, wherein to generate the adjusted bioelectric signal threshold, the processing circuitry is configured to: determine a plurality of average intensity values of the electrical stimulation delivered by the medical device, each average intensity value being determined over a first period of time; for each of the plurality of average intensity values, determine whether an average intensity value is greater than a first average intensity threshold or less than a second average intensity threshold; determine an average intensity ratio based on a number of the average intensity values that are greater than the first average intensity threshold or a number of the average intensity values that are less than the second average intensity threshold over a second period of time; compare the average intensityDocket No.: A0013938W001 ratio to a target average intensity ratio defined by the request, the target average intensity ratio defined by the request indicating whether the medical device is to deliver electrical stimulation more often at the first intensity or the second intensity; based on the comparison, repeatedly adjust the bioelectric signal threshold causing a change in the average intensity ratio until the average intensity ratio is approximately equal to the target average intensity ratio defined by the request to adjust the closed-loop feedback policy, wherein the adjusted bioelectric signal threshold causes the medical device to deliver the electrical stimulation more often at the first intensity than the second intensity.

[0232] Example 3B. The medical device of any of examples IB and 2B, wherein the request does not define the adjusted bioelectric signal threshold.

[0233] Example 4B. The medical device of any of examples 1B-3B, wherein the request comprises a boost mode intensity component indicating whether the medical device is biased to deliver electrical stimulation more often at the first intensity or the second intensity.

[0234] Example 5B. The medical device of any of examples 1B-4B, wherein the first intensity is higher than the second intensity, wherein the processing circuitry is further configured to cause the medical device to deliver the electrical stimulation toggling between the first intensity and the second intensity, and transition to delivering electrical stimulation toggling between the first intensity and an intensity that is lower than the second intensity.

[0235] Example 6B. The medical device of any of examples 1B-5B, wherein the first intensity is higher than the second intensity, and wherein the first intensity is at or near a maximum intensity at which the medical device is to deliver the electrical stimulation.

[0236] Example 7B. The medical device of any of examples 1B-6B, wherein the sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of a patient, and wherein the medical device is implanted within the patient.

[0237] Example 8B. The medical device of example 7B, wherein the LFP signal is sampled at a sampling rate in range of 1-50 Hz.

[0238] Example 9B. The medical device of any of examples 1B-8B, wherein the electrical stimulation is delivered to a brain of a patient, and wherein the medical device is implanted within the patient.

[0239] Example 10B. The medical device of any of examples 1B-9B, wherein the therapy adjustment request is received from a clinician programmer or a patient programmer.

[0240] Example 1 IB. A method for delivery of electrical stimulation, the method comprising: receiving, with processing circuitry of a medical device, a request to adjust a closed-loop feedback policy, the closed-loop feedback policy defining a bioelectric signal threshold for a bioelectric signal; responsive to the request, automatically adjusting, with the processingDocket No.: A0013938W001 circuitry, the bioelectric signal threshold to generate an adjusted bioelectric signal threshold by biasing the medical device to deliver electrical stimulation more often at a first intensity than a second intensity; receiving, with the processing circuitry, characteristic information of a sensed bioelectric signal; and adjusting, with the processing circuitry, delivery of electrical stimulation based on the characteristic information and the adjusted bioelectric signal threshold.

[0241] Example 12B. The method of example 1 IB, wherein generating the adjusted bioelectric signal threshold comprises: determining a plurality of average intensity values of the electrical stimulation delivered by the medical device, each average intensity value being determined over a first period of time; for each of the plurality of average intensity values, determining whether an average intensity value is greater than a first average intensity threshold or less than a second average intensity threshold; determining an average intensity ratio based on a number of the average intensity values that are greater than the first average intensity threshold or a number of the average intensity values that are less than the second average intensity threshold over a second period of time; comparing the average intensity ratio to a target average intensity ratio defined by the request, the target average intensity ratio defined by the request indicating whether the medical device is to deliver electrical stimulation more often at the first intensity or the second intensity; based on the comparison, repeatedly adjusting the bioelectric signal threshold causing a change in the average intensity ratio until the average intensity ratio is approximately equal to the target average intensity ratio defined by the request to adjust the closed-loop feedback policy, wherein the adjusted bioelectric signal threshold causes the medical device to deliver the electrical stimulation more often at the first intensity than the second intensity.

[0242] Example 13B. The method of any of examples 1 IB and 12B, wherein the request does not define the adjusted bioelectric signal threshold.

[0243] Example 14B. The method of any of examples 11B-13B, wherein the request comprises a boost mode intensity component indicating whether the medical device is biased to deliver electrical stimulation more often at the first intensity or the second intensity.

[0244] Example 15B. The method of any of examples 11B-14B, wherein the first intensity is higher than the second intensity, the method further comprising causing the medical device to deliver the electrical stimulation toggling between the first intensity and the second intensity, and transitioning to delivering electrical stimulation toggling between the first intensity and an intensity that is lower than the second intensity.

[0245] Example 16B. The method of any of examples 11B-15B, wherein the first intensity is higher than the second intensity, and wherein the first intensity is at or near a maximum intensity at which the medical device is to deliver the electrical stimulation.Docket No.: A0013938W001

[0246] Example 17B. The method of any of examples 11B-16B, wherein the sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of a patient, and wherein the medical device is implanted within the patient.

[0247] Example 18B. The method of example 17B, wherein the LFP signal is sampled at a sampling rate in range of 1-50 Hz.

[0248] Example 19B. The method of any of examples 11B-18B, wherein the electrical stimulation is delivered to a brain of a patient, and wherein the medical device is implanted within the patient.

[0249] Example 20B. The method of any of examples 11B-19B, wherein the therapy adjustment request is received from a clinician programmer or a patient programmer.

[0250] Example 21B. A computer-readable storage medium comprising instructions that when executed cause one or more processors to perform the method of any of examples 11B-20B.

[0251] Example 22B. A medical device comprising means for performing the method of any of examples 11B-20B.

[0252] Example 1C. A medical device comprising: one or more memories; and processing circuitry coupled to the one or more memories, wherein the processing circuitry is configured to: determine a stimulation intensity at which the medical device is delivering electrical stimulation; based on the stimulation intensity, select an operation mode as one of a dual threshold mode or a single threshold mode, wherein in the dual threshold mode, the medical device determines adjustment to delivery of electrical stimulation based on characteristics of a first sensed bioelectric signal being outside an upper threshold and a lower threshold of the dual threshold mode, and wherein in the single threshold mode, the medical device determines adjustment to delivery of the electrical stimulation based on characteristics of a second sensed bioelectric signal being greater than or less than a single bioelectric signal threshold; and cause the medical device to operate in the selected operation mode.

[0253] Example 2C. The medical device of example 1C, wherein the medical device is implanted in a patient, wherein the first sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of the patient and sampled at a sampling rate in a range of 1-50 Hz.

[0254] Example 3C. The medical device of any of examples 1C and 2C, wherein the medical device is implanted in a patient, wherein the second sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of the patient and sampled at a sampling rate in range of 1-50 Hz and greater than a sampling rate of the first sensed bioelectric signal.

[0255] Example 4C. The medical device of any of examples 1C-3C, wherein the processing circuitry is configured to compare the stimulation intensity to a stimulation intensityDocket No.: A0013938W001 threshold, and wherein to select the operation mode, the processing circuitry is configured to select the dual threshold mode based on the stimulation intensity being less than the stimulation intensity threshold.

[0256] Example 5C. The medical device of any of examples 1C-4C, wherein the processing circuitry is configured to compare the stimulation intensity to a stimulation intensity threshold, and wherein to select the operation mode, the processing circuitry is configured to select the single threshold mode based on the stimulation intensity being greater than the stimulation intensity threshold.

[0257] Example 6C. The medical device of any of examples 1C-5C, wherein to cause the medical device to operate in the selected mode, the processing circuitry is configured to cause the medical device to operate in the single threshold mode, wherein the processing circuitry is configured to, while causing the medical device to operate in the single threshold mode: determine at least one of a first amount of time that the medical device is delivering the electrical stimulation at a first stimulation intensity or a second amount of time that the medical device is delivering the electrical stimulation at a second stimulation intensity, the second stimulation intensity being lower than the first stimulation intensity; and determine whether to transition the medical device from the single threshold mode to the dual threshold mode based on at least one of the first amount of time or the second amount of time.

[0258] Example 7C. The medical device of example 6C, wherein to determine whether to transition, the processing circuitry is configured to: determine a duty cycle based on at least one of the first amount of time and a period of time or the second amount of time and the period of time; compare the duty cycle to a duty cycle threshold; and determine whether to transition based on the comparison.

[0259] Example 8C. The medical device of any of examples 1C-7C, wherein the electrical stimulation is delivered to a brain of a patient, and wherein the medical device is implanted within the patient.

[0260] Example 9C. A method for delivery of electrical stimulation, the method comprising: determining, with processing circuitry of a medical device, a stimulation intensity at which the medical device is delivering electrical stimulation; based on the stimulation intensity, selecting, with the processing circuitry, an operation mode as one of a dual threshold mode or a single threshold mode, wherein in the dual threshold mode, the medical device determines adjustment to delivery of electrical stimulation based on characteristics of a first sensed bioelectric signal being outside an upper threshold and a lower threshold of the dual threshold mode, and wherein in the single threshold mode, the medical device determines adjustment to delivery of the electrical stimulation based on characteristics of a second sensed bioelectric signalDocket No.: A0013938W001 being greater than or less than a single bioelectric signal threshold; and causing, with the processing circuitry, the medical device to operate in the selected operation mode.

[0261] Example 10C. The method of example 9C, wherein the medical device is implanted in a patient, wherein the first sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of the patient and sampled at a sampling rate in range of 1-50 Hz.

[0262] Example 11C. The method of any of examples 9C and 10C, wherein the medical device is implanted in a patient, wherein the second sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of the patient and sampled at a sampling rate in range of 1-50 Hz and greater than a sampling rate of the first sensed bioelectric signal.

[0263] Example 12C. The method of any of examples 9C-11C, further comprising comparing the stimulation intensity to a stimulation intensity threshold, wherein selecting the operation mode comprises selecting the dual threshold mode based on the stimulation intensity being less than the stimulation intensity threshold.

[0264] Example 13C. The method of any of examples 9C-12C, further comprising comparing the stimulation intensity to a stimulation intensity threshold, wherein selecting the operation mode comprises selecting the single threshold mode based on the stimulation intensity being greater than the stimulation intensity threshold.

[0265] Example 14C. The method of any of examples 9C-13C, wherein causing the medical device to operate in the selected mode comprises causing the medical device to operate in the single threshold mode, the method further comprising while causing the medical device to operate in the single threshold mode: determining at least one of a first amount of time that the medical device is delivering the electrical stimulation at a first stimulation intensity or a second amount of time that the medical device is delivering the electrical stimulation at a second stimulation intensity, the second stimulation intensity being lower than the first stimulation intensity; and determining whether to transition the medical device from the single threshold mode to the dual threshold mode based on at least one of the first amount of time or the second amount of time.

[0266] Example 15C. The method of example 14C, wherein determining whether to transition comprises: determining a duty cycle based on at least one of the first amount of time and a period of time or the second amount of time and the period of time; comparing the duty cycle to a duty cycle threshold; and determining whether to transition based on the comparison.

[0267] Example 16C. The method of any of examples 9C-15C, wherein the electrical stimulation is delivered to a brain of a patient, and wherein the medical device is implanted within the patient.Docket No.: A0013938W001

[0268] Example 17C. A computer-readable storage medium comprising instructions that when executed cause one or more processors to perform the method of any of examples 9C-16C.

[0269] Example 18C. A medical device comprising means for performing the method of any of examples 9C-16C.

[0270] The techniques of this disclosure may be implemented, at least in part, in hardware, software, firmware or any combination thereof. For example, various aspects of the described techniques may be implemented within one or more processors or processing circuitry, including one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. The term “processor” or “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry. A control unit including hardware may also perform one or more of the techniques of this disclosure.

[0271] Such hardware, software, and firmware may be implemented within the same device or within separate devices to support the various operations and functions described in this disclosure. In addition, any of the described units, circuits or components may be implemented together or separately as discrete but interoperable logic devices. Depiction of different features as circuits or units is intended to highlight different functional aspects and does not necessarily imply that such circuits or units must be realized by separate hardware or software components. Rather, functionality associated with one or more circuits or units may be performed by separate hardware or software components or integrated within common or separate hardware or software components.

[0272] The techniques described in this disclosure may also be embodied or encoded in a computer-readable medium, such as a computer-readable storage medium, containing instructions that may be described as non-transitory media. Instructions embedded or encoded in a computer-readable storage medium may cause a programmable processor, or other processor, to perform the method, e.g., when the instructions are executed. Computer readable storage media may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a CD-ROM, a floppy disk, a cassette, magnetic media, optical media, or other computer readable media.

[0273] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

Docket No.: A0013938W001 WHAT IS CLAIMED IS:

1. A medical device comprising:one or more memories; andprocessing circuitry coupled to the one or more memories, wherein the processing circuitry is configured to:determine a stimulation intensity at which the medical device is delivering electrical stimulation;based on the stimulation intensity, select an operation mode as one of a dual threshold mode or a single threshold mode, wherein in the dual threshold mode, the medical device determines adjustment to delivery of electrical stimulation based on characteristics of a first sensed bioelectric signal being outside an upper threshold and a lower threshold of the dual threshold mode, and wherein in the single threshold mode, the medical device determines adjustment to delivery of the electrical stimulation based on characteristics of a second sensed bioelectric signal being greater than or less than a single bioelectric signal threshold; andcause the medical device to operate in the selected operation mode.

2. The medical device of claim 1, wherein the medical device is implanted in a patient, wherein the first sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of the patient and sampled at a sampling rate in a range of 1-50 Hz.

3. The medical device of any of claims 1 and 2, wherein the medical device is implanted in a patient, wherein the second sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of the patient and sampled at a sampling rate in range of 1-50 Hz and greater than a sampling rate of the first sensed bioelectric signal.

4. The medical device of any of claims 1-3, wherein the processing circuitry is configured to compare the stimulation intensity to a stimulation intensity threshold, and wherein to select the operation mode, the processing circuitry is configured to select the dual threshold mode based on the stimulation intensity being less than the stimulation intensity threshold.

5. The medical device of any of claims 1-4, wherein the processing circuitry is configured to compare the stimulation intensity to a stimulation intensity threshold, and wherein to select theDocket No.: A0013938W001 operation mode, the processing circuitry is configured to select the single threshold mode based on the stimulation intensity being greater than the stimulation intensity threshold.

6. The medical device of any of claims 1-5, wherein to cause the medical device to operate in the selected mode, the processing circuitry is configured to cause the medical device to operate in the single threshold mode, wherein the processing circuitry is configured to, while causing the medical device to operate in the single threshold mode:determine at least one of a first amount of time that the medical device is delivering the electrical stimulation at a first stimulation intensity or a second amount of time that the medical device is delivering the electrical stimulation at a second stimulation intensity, the second stimulation intensity being lower than the first stimulation intensity; anddetermine whether to transition the medical device from the single threshold mode to the dual threshold mode based on at least one of the first amount of time or the second amount of time.

7. The medical device of claim 6, wherein to determine whether to transition, the processing circuitry is configured to:determine a duty cycle based on at least one of the first amount of time and a period of time or the second amount of time and the period of time;compare the duty cycle to a duty cycle threshold; anddetermine whether to transition based on the comparison.

8. The medical device of any of claims 1-7, wherein the electrical stimulation is delivered to a brain of a patient, and wherein the medical device is implanted within the patient.

9. A method for delivery of electrical stimulation, the method comprising:determining, with processing circuitry of a medical device, a stimulation intensity at which the medical device is delivering electrical stimulation;based on the stimulation intensity, selecting, with the processing circuitry, an operation mode as one of a dual threshold mode or a single threshold mode, wherein in the dual threshold mode, the medical device determines adjustment to delivery of electrical stimulation based on characteristics of a first sensed bioelectric signal being outside an upper threshold and a lower threshold of the dual threshold mode, and wherein in the single threshold mode, the medical device determines adjustment to delivery of the electrical stimulation based on characteristics ofDocket No.: A0013938W001 a second sensed bioelectric signal being greater than or less than a single bioelectric signal threshold; andcausing, with the processing circuitry, the medical device to operate in the selected operation mode.

10. The method of claim 9, wherein the medical device is implanted in a patient, wherein the first sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of the patient and sampled at a sampling rate in range of 1-50 Hz.

11. The method of any of claims 9 and 10, wherein the medical device is implanted in a patient, wherein the second sensed bioelectric signal is a local field potential (LFP) signal sensed within a brain of the patient and sampled at a sampling rate in range of 1-50 Hz and greater than a sampling rate of the first sensed bioelectric signal.

12. The method of any of claims 9-11, further comprising comparing the stimulation intensity to a stimulation intensity threshold, wherein selecting the operation mode comprises selecting the dual threshold mode based on the stimulation intensity being less than the stimulation intensity threshold.

13. The method of any of claims 9-12, further comprising comparing the stimulation intensity to a stimulation intensity threshold, wherein selecting the operation mode comprises selecting the single threshold mode based on the stimulation intensity being greater than the stimulation intensity threshold.

14. The method of any of claims 9-13, wherein causing the medical device to operate in the selected mode comprises causing the medical device to operate in the single threshold mode, the method further comprising while causing the medical device to operate in the single threshold mode:determining at least one of a first amount of time that the medical device is delivering the electrical stimulation at a first stimulation intensity or a second amount of time that the medical device is delivering the electrical stimulation at a second stimulation intensity, the second stimulation intensity being lower than the first stimulation intensity; anddetermining whether to transition the medical device from the single threshold mode to the dual threshold mode based on at least one of the first amount of time or the second amount of time.Docket No.: A0013938W00115. The method of claim 14, wherein determining whether to transition comprises:determining a duty cycle based on at least one of the first amount of time and a period of time or the second amount of time and the period of time;comparing the duty cycle to a duty cycle threshold; anddetermining whether to transition based on the comparison.

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