Method for determining stimulus intensity of target regulatory cortex, computing device and computer program product
By constructing anisotropic conductivity head model and calculating scaling factors, the problem of difficult to accurately determine the transcranial magnetic stimulation intensity of target-regulating cortex such as the brain prefrontal lobe is solved, and more accurate stimulation intensity adjustment and treatment effect are achieved.
Patent Information
- Application Number
- CN202510125698.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-27
- Publication Date
- 2025-04-15
AI Technical Summary
How to accurately determine the intensity of transcranial magnetic stimulation in target regulatory cortex such as the prefrontal lobe of the brain, given that this area does not produce an observable response to transcranial magnetic stimulation.
By using transcranial magnetic stimulation experiments to obtain the motion threshold of the primary motor cortex, an anisotropic conductivity head model was constructed based on magnetic resonance imaging data, the electric field value of the test area was determined, the scaling factor was calculated, and the stimulation intensity was adjusted based on the scaling factor to determine the target stimulation intensity of the target regulatory cortex.
A more accurate determination of the intensity of stimulation of the target regulatory cortex is achieved, and the accuracy of transcranial magnetic stimulation treatment or research is improved.
Smart Images
Figure CN119818839A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to the field of computer technology applications, and in particular to a method for determining the stimulation intensity of a target regulated cortex, a computing device, and a computer program product. Background Art
[0002] Transcranial magnetic stimulation (TMS) is a technology that uses an alternating magnetic field to act on the cerebral cortex to generate an induced current, thereby affecting neuronal activity. When the transcranial magnetic stimulation coil generates an alternating magnetic field outside the brain, the magnetic field can penetrate the skull and induce an electric field in the neural tissue of the cerebral cortex. According to Faraday's law of electromagnetic induction, a changing magnetic field will generate an electromotive force in the brain's neural tissue, thereby inducing an induced current. This induced current can directly act on the cell membrane of neurons and change the potential state of the cell membrane. When the induced current reaches a certain intensity, it can depolarize the neuronal cell membrane and reach the excitation threshold of the neurons, thereby inducing action potentials and activating neurons. For example, when transcranial magnetic stimulation is performed on the primary motor cortex, neurons in this area can be stimulated to generate action potentials, thereby inducing movement of the contralateral hand. Therefore, the motor threshold of the primary motor cortex can be defined as the stimulation intensity of transcranial magnetic stimulation that just induces movement of the contralateral hand.
[0003] Transcranial magnetic stimulation can not only directly activate single neurons, but also affect the brain's neural circuits. By regulating the activity of neurons in specific brain areas, it changes the release of neurotransmitters and the transmission of neural signals, thereby affecting brain function. For example, when treating mental illnesses such as depression, transcranial magnetic stimulation of the prefrontal cortex and other related brain areas may regulate the neural circuits related to emotion regulation in this area, affecting the release and transmission of neurotransmitters such as serotonin and dopamine, thereby improving the patient's emotional state and cognitive function.
[0004] However, for relevant brain areas such as the prefrontal lobe of the brain, transcranial magnetic stimulation does not produce observable responses. Therefore, how to accurately determine the stimulation intensity of target regulatory cortices such as the prefrontal lobe of the brain has become a technical problem that needs to be solved urgently. Summary of the invention
[0005] The embodiments of the present application provide a method, apparatus, computing device and computer program product for determining the stimulation intensity of a target regulated cortex.
[0006] In a first aspect, an embodiment of the present application provides a method for determining the stimulation intensity of a target regulated cortex, comprising:
[0007] The first motor threshold of the primary motor cortex of the subject's head was obtained by transcranial magnetic stimulation experiment;
[0008] Based on the magnetic resonance imaging data of the subject's head, constructing an anisotropic conductivity head model corresponding to the subject's head;
[0009] Determining in the anisotropic conductivity head model a first test area corresponding to the primary motor cortex and a second test area corresponding to the target regulatory cortex;
[0010] Using the stimulation intensity value corresponding to the first motion threshold, respectively performing electric field simulation on the first test area and the second test area to determine the first electric field value and the second electric field value generated in the first test area and the second test area;
[0011] determining a scaling factor based on the first electric field value and the second electric field value;
[0012] Based on the scaling factor and the first motion threshold, a target stimulation intensity of the target regulated cortex is determined.
[0013] In a second aspect, an embodiment of the present application provides a device for determining the stimulation intensity of a target regulated cortex, comprising:
[0014] A first threshold determination module, used for obtaining a first motor threshold of the primary motor cortex of the subject's head by using a transcranial magnetic stimulation experiment;
[0015] A model building module, used for building an anisotropic conductivity head model corresponding to the subject's head based on the magnetic resonance imaging data of the subject's head;
[0016] A test area determination module, used to determine a first test area corresponding to the primary motor cortex and a second test area corresponding to the target regulatory cortex in the anisotropic conductivity head model;
[0017] an electric field simulation module, configured to perform electric field simulation on the first test area and the second test area respectively by using the stimulation intensity value corresponding to the first motion threshold, so as to determine the first electric field value and the second electric field value generated at the first test area and the second test area;
[0018] a scaling factor determination module, configured to determine a scaling factor based on the first electric field value and the second electric field value;
[0019] An intensity determination module is used to determine a target stimulation intensity of the target regulated cortex based on the scaling factor and the first motion threshold.
[0020] In a third aspect, an embodiment of the present application provides a computing device, including a processing component and a storage component;
[0021] The storage component stores one or more computer instructions; the one or more computer instructions are used to be called and executed by the processing component to implement the method for determining the stimulation intensity of the target regulated cortex provided in the embodiment of the present application.
[0022] In a fourth aspect, a computer program product is provided in an embodiment of the present application, including a computer program / instruction, which, when executed by a processing component, provides a method for determining the stimulation intensity of a target regulatory cortex provided in an embodiment of the present application.
[0023] In an embodiment of the present application, a first motor threshold of the primary motor cortex of a subject's head is obtained by using a transcranial magnetic stimulation experiment; an anisotropic conductivity head model corresponding to the subject's head is constructed based on the magnetic resonance imaging data of the subject's head; a first test area corresponding to the primary motor cortex and a second test area corresponding to a target regulated cortex are determined in the anisotropic conductivity head model; an electric field simulation is performed on the first test area and the second test area respectively using the stimulation intensity value corresponding to the first motor threshold, so as to determine the first electric field value and the second electric field value generated at the first test area and the second test area; a scaling factor is determined based on the first electric field value and the second electric field value; a technical solution for determining the target stimulation intensity of the target regulated cortex based on the scaling factor and the first motor threshold can use the ratio of the first electric field value to the second electric field value as the scaling factor, and adjust the first motor threshold according to the electric field difference of different cortical areas, so as to obtain a more accurate target stimulation intensity of the target regulated cortex, thereby providing support for more accurate transcranial magnetic stimulation treatment or research.
[0024] These and other aspects of the present application will become more clearly understood in the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0026] Figure 1 A flowchart of a method for determining stimulation intensity of a target regulated cortex provided by an embodiment of the present application is shown;
[0027] Figure 2 A block diagram of a device for determining stimulation intensity of a target regulated cortex provided by an embodiment of the present application is shown;
[0028] Figure 3A block diagram of a computing device provided by an embodiment of the present application is shown. DETAILED DESCRIPTION
[0029] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.
[0030] In some of the processes described in the specification and claims of this application and the above-mentioned figures, multiple operations that appear in a specific order are included, but it should be clearly understood that these operations may not be executed in the order in which they appear in this article or executed in parallel. The serial numbers of the operations, such as 101, 102, etc., are only used to distinguish between different operations, and the serial numbers themselves do not represent any execution order. In addition, these processes may include more or fewer operations, and these operations may be executed in sequence or in parallel. It should be noted that the descriptions of "first", "second", etc. in this article are used to distinguish different messages, devices, modules, etc., do not represent the order of precedence, and do not limit the "first" and "second" to be different types.
[0031] Transcranial magnetic stimulation (TMS) is a technology that uses an alternating magnetic field to act on the cerebral cortex to generate an induced current, thereby affecting neuronal activity. When the transcranial magnetic stimulation coil generates an alternating magnetic field outside the brain, the magnetic field can penetrate the skull and induce an electric field in the neural tissue of the cerebral cortex. According to Faraday's law of electromagnetic induction, a changing magnetic field will generate an electromotive force in the brain's neural tissue, thereby inducing an induced current. This induced current can directly act on the cell membrane of neurons and change the potential state of the cell membrane. When the induced current reaches a certain intensity, it can depolarize the neuronal cell membrane and reach the excitation threshold of the neurons, thereby inducing action potentials and activating neurons. For example, when transcranial magnetic stimulation is performed on the primary motor cortex, neurons in this area can be stimulated to generate action potentials, thereby inducing movement of the contralateral hand. Therefore, the motor threshold of the primary motor cortex can be defined as the stimulation intensity of transcranial magnetic stimulation that just induces movement of the contralateral hand.
[0032] Transcranial magnetic stimulation can not only directly activate single neurons, but also affect the brain's neural circuits. By regulating the activity of neurons in specific brain areas, it changes the release of neurotransmitters and the transmission of neural signals, thereby affecting brain function. For example, when treating mental illnesses such as depression, transcranial magnetic stimulation of the prefrontal cortex and other related brain areas may regulate the neural circuits related to emotion regulation in this area, affecting the release and transmission of neurotransmitters such as serotonin and dopamine, thereby improving the patient's emotional state and cognitive function.
[0033] However, for relevant brain areas such as the prefrontal lobe of the brain, transcranial magnetic stimulation does not produce observable responses. Therefore, how to accurately determine the stimulation intensity of target regulatory cortices such as the prefrontal lobe of the brain has become a technical problem that needs to be solved urgently.
[0034] In order to solve the technical problems existing in the related art, in an embodiment of the present application, a first motor threshold of the primary motor cortex of the subject's head is obtained by using a transcranial magnetic stimulation experiment; an anisotropic conductivity head model corresponding to the subject's head is constructed based on the magnetic resonance imaging data of the subject's head; a first test area corresponding to the primary motor cortex and a second test area corresponding to the target regulated cortex are determined in the anisotropic conductivity head model; an electric field simulation is performed on the first test area and the second test area respectively using the stimulation intensity value corresponding to the first motor threshold, so as to determine the first electric field value and the second electric field value generated at the first test area and the second test area; a scaling factor is determined based on the first electric field value and the second electric field value; a technical solution for determining the target stimulation intensity of the target regulated cortex based on the scaling factor and the first motor threshold can use the ratio of the first electric field value to the second electric field value as the scaling factor, and adjust the first motor threshold according to the electric field difference of different cortical areas, so as to obtain a more accurate target stimulation intensity of the target regulated cortex, thereby providing support for more accurate transcranial magnetic stimulation treatment or research.
[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.
[0036] Figure 1 A flowchart of a method for determining the stimulation intensity of a target regulated cortex provided by an embodiment of the present application is shown. Figure 1 As shown, the method may specifically include the following steps:
[0037] 101: Using transcranial magnetic stimulation experiment to obtain the first motor threshold of the primary motor cortex of the subject's head.
[0038] In an embodiment of the present application, magnetic stimulation of different intensities can be applied to the primary motor cortex of the subject through a transcranial magnetic stimulation device, while the response of the contralateral hand muscles of the subject's body is recorded, thereby determining the first motor threshold.
[0039] The transcranial magnetic stimulation device is mainly composed of a stimulator, a coil and other parts. The stimulator can generate rapidly changing electric current, and the coil converts this electric current into a magnetic field. When the coil is placed at a specific position on the subject's head, the magnetic field generated can penetrate tissues such as the skull and scalp non-invasively and act on nerve cells inside the brain, thereby changing the membrane potential of nerve cells, affecting the excitability of nerve cells and the transmission of nerve signals.
[0040] The primary motor cortex is located in the precentral gyrus of the brain and is the area in the cerebral cortex that directly controls body movement. The nerve cells here are arranged in an orderly manner according to the motor functions of various parts of the body, forming a precise motor control map. From the top to the bottom of the cortex, they correspond to the motor control areas of different parts such as the lower limbs, upper limbs, head and face. When the nerve cells in the primary motor cortex are activated, nerve impulses are sent out, which eventually reach the corresponding muscles through the nerve conduction pathways, causing muscle contraction and movement.
[0041] In a transcranial magnetic stimulation experiment, the intensity of magnetic stimulation applied to the primary motor cortex can be gradually increased from a low stimulation intensity through a transcranial magnetic stimulation device. The increase in magnetic stimulation intensity can be a continuous and fine adjustment process, and the amplitude of each adjustment is usually small to accurately find the stimulation intensity that triggers a specific response.
[0042] Since the primary motor cortex has the characteristic of contralateral dominance in controlling the body's muscles, that is, the left primary motor cortex mainly controls the movement of the right side of the body, and the right primary motor cortex mainly controls the movement of the left side of the body. Therefore, when stimulating the primary motor cortex, the response of the contralateral hand muscles of the subject can be recorded. For example, devices such as electromyography (EMG) can be used to record the electrical activity of muscles. EMG can amplify the weak electrical signals generated when muscles contract and convert them into waveform data that can be observed and analyzed, thereby accurately reflecting whether the muscles have contracted and the intensity and duration of the contraction.
[0043] In the process of continuously adjusting the stimulation intensity, when the stimulation intensity reaches a certain value, the contralateral hand muscles begin to show obvious movement reactions, such as slight tremors of the fingers, slight bending of the wrist, etc. The stimulation intensity that can just cause the hand muscles to move can be used as the first movement threshold.
[0044] 102: Based on the magnetic resonance imaging data of the subject's head, construct an anisotropic conductivity head model corresponding to the subject's head.
[0045] Magnetic resonance imaging (MRI) is a technology that uses magnetic fields and radio waves to generate detailed images of the human body. For the MRI data of the subject's head, it can clearly show the various anatomical structures of the head, such as the scalp, skull, gray matter, white matter, cerebrospinal fluid, and the boundaries of various tissues. These image data are obtained by scanning multiple levels (slices), and each level contains information about the position, shape, size, and relative position relationship of the tissues within that level.
[0046] Therefore, an anisotropic conductivity head model can be constructed based on the anatomical structure in the MRI data.
[0047] The construction method of the anisotropic conductivity head model will be described in detail in the following examples.
[0048] 103: Determine in the anisotropic conductivity head model a first test area corresponding to the primary motor cortex and a second test area corresponding to the target regulatory cortex.
[0049] The target regulatory cortex may be a part to which transcranial magnetic stimulation does not produce an observable response. In actual application scenarios, the target regulatory cortex can be selected according to the research purpose. For example, in the treatment and research of depression, the prefrontal cortex, cingulate cortex and other areas can be used as target regulatory areas.
[0050] In a possible implementation, the anisotropic conductivity head model can be registered with a standard brain map, and the brain structure in the anisotropic conductivity head model can be matched with the corresponding area in the brain map, so as to accurately determine the first test area and the second test area in the head model according to the definition and annotation of the primary motor cortex and the target regulatory cortex in the brain map. Among them, the standard brain map can include the Talairach brain map, the MNI brain map, etc.
[0051] In another possible implementation, an image segmentation algorithm, a spatial registration algorithm, and other methods can also be used to determine the first test area corresponding to the primary motor cortex and the second test area corresponding to the target regulatory cortex in the anisotropic conductivity head model. For example, when using an image segmentation algorithm, the primary motor cortex and the target regulatory cortex can be separated from the surrounding brain tissue by using algorithms based on threshold segmentation, regional growth, level set, etc., and their pixel ranges in the image can be determined, and then the corresponding test areas can be determined in the anisotropic conductivity head model; for example, when using a spatial registration algorithm, image data or brain maps of different modalities can be fused with the anisotropic conductivity head model to ensure that the spatial positions of different data correspond accurately. For example, based on registration algorithms such as rigid body transformation, affine transformation, or nonlinear transformation, the position information of the primary motor cortex and the target regulatory cortex in the MRI image is accurately mapped to the anisotropic conductivity head model, thereby accurately determining the spatial positions of the first test area and the second test area.
[0052] 104: Performing electric field simulation on the first test area and the second test area respectively using the stimulation intensity value corresponding to the first motion threshold, so as to determine the first electric field value and the second electric field value generated in the first test area and the second test area.
[0053] In an embodiment of the present application, when the first motor threshold of the primary motor cortex of the subject's head is obtained by using a transcranial magnetic stimulation experiment, the stimulation position, coil orientation, stimulation intensity, and magnetic vector potential model of the stimulation coil of the transcranial magnetic stimulation device can be recorded. Then, based on the stimulation position, coil orientation, stimulation intensity, and magnetic vector potential model of the stimulation coil, the distribution of the magnetic field in the head tissue and the induced electric field distribution under given stimulation conditions can be calculated according to the basic principles of electromagnetism, such as Maxwell's equations, combined with the physical properties of each anatomical structure in the anisotropic conductivity head model.
[0054] During the calculation process, the anisotropic conductivity head model can be discretized into a large number of small units, and then the electric field calculation is performed on each unit to finally obtain the electric field distribution of the entire head.
[0055] After obtaining the electric field distribution of the entire head, the electric field values of the first test area and the second test area can be extracted from the calculation results according to their position information in the head model, and recorded as the first electric field value and the second electric field value, respectively.
[0056] 105: Determine a scaling factor based on the first electric field value and the second electric field value.
[0057] 106: Determine a target stimulation intensity of the target regulatory cortex based on the scaling factor and the first motion threshold.
[0058] The first electric field value and the second electric field value are results obtained in a specific electric field simulation process, and they reflect the intensity of the electric field in the first test area and the second test area.
[0059] Determining the scaling factor based on the first electric field value and the second electric field value may be specifically implemented as follows:
[0060] The ratio of the first electric field value to the second electric field value is used as a scaling factor.
[0061] In some embodiments, based on the scaling factor and the first motion threshold, determining the target stimulation intensity of the target regulated cortex can be specifically implemented as follows:
[0062] The scaling factor was multiplied by the first motor threshold to obtain the target stimulation intensity.
[0063] Assume that the first electric field value is E 1 , the second electric field value is E 2 , then the scaling factor This scaling factor reflects the multiple relationship of the electric field strength of the second test area relative to the electric field strength of the first test area.
[0064] In a physical sense, if k>1, it means that the electric field strength of the second test area is greater than that of the first test area. Conversely, if k<1, it means that the electric field strength of the second test area is relatively small. For example, when k=2, it means that under the same stimulation conditions, the electric field strength of the second test area is twice that of the first test area. This may be due to the different tissue characteristics of the two test areas.
[0065] In practical applications, because different cortical areas may produce electric fields of different strengths for the same stimulation intensity, and these electric fields will have different effects on neural activity, the scaling factor can characterize the difference in electric field distribution in different cortical areas during transcranial magnetic stimulation (TMS). By calculating this scaling factor, this difference can be quantified, providing a basis for subsequent adjustment of the stimulation intensity.
[0066] The first motor threshold of the primary motor cortex obtained by transcranial magnetic stimulation experiment is denoted as T 1 The target stimulation intensity of the target regulatory cortex is determined by the scaling factor and recorded as T target , which can be expressed as T target = k × T 1 .
[0067] The first motion threshold T 1In the transcranial magnetic stimulation experiment, the minimum stimulation intensity that can induce a specific motor response is found by gradually increasing the stimulation intensity, which reflects the sensitivity of the neural tissue to stimulation. After the electric field scaling factor k of different regions is determined, the stimulation intensity can be adjusted according to the electric field characteristics of different regions by multiplying it by the first motor threshold to achieve the expected stimulation effect.
[0068] For example, if the first motion threshold T 1 = 10 (assuming the unit is millitesla), scaling factor k = 1.5, then the target stimulus intensity T target =1.5×10=15 millitesla. This means that for the target modulated cortex, in order to achieve a similar neuromodulatory effect as in the first motor threshold area, the stimulation intensity needs to be adjusted to 15 millitesla. Because the electric field distribution in the target modulated cortex is different from that in the first motor threshold area, the stimulation intensity needs to be adjusted accordingly. Such calculations can more accurately control the effect of stimulation in different cortical areas to adapt to the different responses of neural tissue in different areas to stimulation, and improve the effectiveness and pertinence of transcranial magnetic stimulation treatment or research.
[0069] In an embodiment of the present application, a first motor threshold of the primary motor cortex of the subject's head is obtained by using a transcranial magnetic stimulation experiment; an anisotropic conductivity head model corresponding to the subject's head is constructed based on the magnetic resonance imaging data of the subject's head; a first test area corresponding to the primary motor cortex and a second test area corresponding to the target regulated cortex are determined in the anisotropic conductivity head model; an electric field simulation is performed on the first test area and the second test area respectively using the stimulation intensity value corresponding to the first motor threshold, so as to determine the first electric field value and the second electric field value generated at the first test area and the second test area; a scaling factor is determined based on the first electric field value and the second electric field value; a technical solution for determining the target stimulation intensity of the target regulated cortex based on the scaling factor and the first motor threshold can use the ratio of the first electric field value to the second electric field value as the scaling factor, and adjust the first motor threshold according to the electric field difference in different cortical areas, so as to obtain a more accurate target stimulation intensity of the target regulated cortex, thereby providing support for more accurate transcranial magnetic stimulation treatment or research.
[0070] In some embodiments, constructing an anisotropic conductivity head model corresponding to the subject's head based on the magnetic resonance imaging data of the subject's head can be specifically implemented as follows:
[0071] acquiring magnetic resonance imaging data of the subject's head;
[0072] In the magnetic resonance imaging data, a plurality of tissue regions are identified;
[0073] Performing surface reconstruction on boundaries of multiple tissue regions to generate a head model including the multiple tissue regions;
[0074] Corresponding conductivity values are respectively configured for multiple tissue regions of the head model to generate an anisotropic conductivity head model, wherein different conductivity values corresponding to different tissue regions are different.
[0075] In an embodiment of the present application, a tissue segmentation algorithm can be used to separate the five tissues of skin, skull, cerebrospinal fluid, gray matter and white matter from the magnetic resonance imaging data according to the signal strength and characteristic differences of different tissues in the magnetic resonance imaging data. After completing the tissue segmentation, the boundaries of each tissue can be further extracted. In an embodiment of the present application, the extraction of tissue boundaries can be achieved by an edge detection algorithm, and the edge detection algorithm can include, for example, a Canny edge detection algorithm, etc., which can identify the boundary pixels between tissues in the image, thereby obtaining a high-resolution surface boundary.
[0076] By performing surface reconstruction on the boundaries of each tissue region, the surfaces of each tissue can be combined to form a complete head model. This head model not only contains the geometric shape information of the tissue, but also clearly shows the spatial position relationship between different tissues, just like a three-dimensional head anatomy Figure 1 Likewise, it can be a closed or open 3D model.
[0077] Among them, conductivity is a physical quantity that describes the ability of a substance to conduct electricity. It reflects the conduction of current in a substance under a unit electric field strength. In head tissues, since different tissues have different microstructures and physiological properties, the conductivity of different tissues is different. For example, cerebrospinal fluid is a liquid containing a variety of ions, whose ions can move relatively freely, so the conductivity is relatively high; while the skull is a solid structure with limited ion movement and relatively low conductivity.
[0078] After the head model is constructed, a corresponding conductivity value can be assigned to each tissue region in the head model according to known tissue characteristics and existing experimental data. The conductivity value can be obtained from existing biophysical literature or experimental measurements.
[0079] Combining the various tissue regions with configured conductivity values together forms a complete anisotropic conductivity head model, which includes both the geometry and spatial distribution of the head tissues and the conductivity properties of different tissues, including the directional properties of anisotropic tissues.
[0080] In some embodiments, using the stimulation intensity value corresponding to the first motion threshold, performing electric field simulation on the first test area to determine the first electric field value generated at the first test area can be specifically implemented as follows:
[0081] Determining a first primary electric field generated at a first test area, and a first secondary electric field, wherein the first secondary electric field is generated due to the difference in conductivity values between different tissue areas;
[0082] Based on the first primary electric field and the first secondary electric field, a first electric field value is obtained.
[0083] The first primary electric field is an electric field directly induced by the magnetic field generated by the transcranial magnetic stimulation device in the first test area. Its calculation is usually based on the basic principles of electromagnetism, especially Faraday's law of electromagnetic induction. Among them, B can represent the magnetic induction intensity, It can represent the partial derivative of the magnetic induction intensity B with respect to time. When the transcranial magnetic stimulation device stimulates with the stimulation intensity value corresponding to the first motor threshold, a magnetic field B(t) that changes with time is generated. According to the above law, an electric field can be induced in the brain tissue.
[0084] For the first test area, the first primary electric field at the first test area can be calculated by using the integral form or differential form of the Maxwell equations combined with the geometric information of the head model. For example, for a first test area located at a certain distance r from the stimulation coil, the Biot-Savart law can be used to calculate the magnetic field at that location, and then the first primary electric field at that location can be calculated according to Faraday's law of electromagnetic induction. During the calculation, numerical calculation methods such as finite element analysis and boundary element analysis can be used to perform integral or differential operations on the entire head area.
[0085] The first secondary electric field is generated due to the different conductivity values between different tissue areas. When the current propagates in different tissues, due to the different conductivity of different tissues, reflection, refraction and scattering of the electric field will occur at the tissue interface, thus generating a secondary electric field.
[0086] According to the constructed anisotropic conductivity head model, the conductivity values of different tissue regions are clarified, such as skin, skull, cerebrospinal fluid, gray matter and white matter, which all have different conductivity. When the current enters from one tissue to another, according to the boundary conditions of the electromagnetic field, such as the continuity of the tangential and normal components of the electric and magnetic fields at the tissue boundary, the changes in the electric and magnetic fields at the tissue interface can be calculated.
[0087] For each tissue boundary within the first test region, using these boundary conditions and the known tissue conductivity, the first secondary electric field generated near the boundary due to the conductivity difference can be calculated by solving the electromagnetic equations at the interface.
[0088] After the first primary electric field and the first secondary electric field are calculated, the first electric field value can be obtained by performing vector superposition on the first primary electric field and the first secondary electric field.
[0089] In some embodiments, after generating a head model including multiple tissue regions, the method may further include:
[0090] The head model is divided into a finite number of grid cells.
[0091] In some embodiments, determining the first primary electric field generated at the first test area, and the first secondary electric field comprises:
[0092] For any grid cell of the first test area, a first primary electric field and a first secondary electric field generated at the grid cell are determined.
[0093] After generating a head model including multiple tissue regions (such as skin, skull, cerebrospinal fluid, gray matter, white matter, etc.), different tissue regions can be filled with tetrahedrons one by one and divided into a finite number of grid cells.
[0094] By dividing the head model into a finite number of grid units, numerical calculations and simulations can be performed more easily. Because in actual physical problems (such as the distribution of the electric field generated by transcranial magnetic stimulation on the head), it is difficult to directly perform accurate calculations on a continuous head model, by dividing the grid units and discretizing the head model, numerical methods (such as the finite element method, the finite difference method, etc.) can be used to independently calculate each grid unit, thereby obtaining the distribution of relevant physical quantities of the entire head model.
[0095] In an embodiment of the present application, for each tissue region, a special algorithm (such as a three-dimensional extension of the Delaunay triangulation algorithm) can be used to generate tetrahedrons. The algorithm can construct tetrahedrons based on points in the tissue region (such as tissue boundary points or internal sampling points reconstructed from medical imaging data), so that these tetrahedrons can tightly fill the entire tissue region, and adjacent tetrahedrons are interconnected to form a complete grid structure.
[0096] After each tissue region is filled with tetrahedrons, each tetrahedron becomes a mesh unit. In this way, the entire head model is divided into a finite number of mesh units.
[0097] In the embodiments of the present application, the finite element method may be used to calculate the magnitude and direction of the first primary electric field and the first secondary electric field induced by the magnetic field generated by the stimulation coil at each grid unit.
[0098] In some embodiments, obtaining the first electric field value based on the first primary electric field and the first secondary electric field may be specifically implemented as follows:
[0099] For any grid unit in the first test area, determining a first sub-electric field value corresponding to the grid unit based on the first primary electric field and the first secondary electric field;
[0100] Based on the number of grid cells included in the first test area, an average value of a plurality of first sub-electric field values is determined to obtain a first electric field value.
[0101] For any grid unit in the first test area, the first primary electric field and the first secondary electric field are both electric field components existing at the grid unit. According to the superposition principle of electric field, the total electric field at a point in space is the vector sum of all electric field components. Therefore, for each grid unit, its corresponding first sub-electric field value is the vector superposition of the first primary electric field and the first secondary electric field at the grid unit.
[0102] The first test area includes a plurality of grid units, each of which has its corresponding first sub-electric field value. Since these grid units together constitute the first test area, a value representing the electric field characteristics of the entire first test area can be obtained by using the average method.
[0103] It should be noted that the above description is based on the determination of the electric field value of the first test area as an example. The method for determining the electric field value of the second test area may be the same or similar to the method for determining the electric field value of the first test area, and will not be repeated here.
[0104] In some embodiments, obtaining the first motor threshold of the primary motor cortex of the subject's head by using a transcranial magnetic stimulation experiment can be specifically implemented as follows:
[0105] Perform the following steps iteratively:
[0106] determining a first stimulus intensity;
[0107] The primary motor cortex was stimulated with the first stimulus intensity, and the motor evoked potentials of the contralateral hand muscles were recorded;
[0108] Determine whether the motor evoked potential meets the preset conditions. If so, determine the first stimulation intensity as the first motor threshold; if not, determine a second secondary intensity greater than the first secondary intensity, and determine the second secondary intensity as the first stimulation intensity until the motor evoked potential meets the preset conditions.
[0109] In some embodiments, the preset condition includes the number of times the amplitude value of the motor evoked potential reaches a preset amplitude threshold.
[0110] At the beginning of the transcranial magnetic stimulation experiment, an initial stimulation intensity, i.e., the first stimulation intensity, can be determined. The selection of this initial stimulation intensity can be based on experience, preliminary experimental results, or some basic physiological characteristics of the subject (such as age, physical condition, etc.). For example, for a general adult subject, a relatively low stimulation intensity may be selected first, such as 30%-50% of the maximum output intensity of the transcranial magnetic stimulation device as the first stimulation intensity.
[0111] The primary motor cortex of the subject's head can then be stimulated using the determined first stimulation intensity. The primary motor cortex is the area of the brain responsible for controlling the movement of the contralateral body. When this area is subjected to transcranial magnetic stimulation, nerve impulses are generated and transmitted to the contralateral hand muscles, causing electrical activity in the muscles, namely motor evoked potentials (MEPs). These electrical activities can be recorded by electrodes placed on the contralateral hand muscles. The recording device will collect and store information such as the waveform and amplitude of the motor evoked potential for subsequent analysis.
[0112] Among them, the preset condition is a criterion for judging whether the current stimulation intensity is the first motor threshold. In some embodiments, the preset condition includes the number of times the amplitude value of the motor evoked potential reaches the preset amplitude threshold. For example, the preset amplitude threshold can be set to 50 microvolts, and the preset number of times can be set to 5 times. This means that the preset condition is considered to be met only when the amplitude value of the motor evoked potential reaches 50 microvolts for a cumulative total of 5 times.
[0113] During the experiment, the recorded motor evoked potentials can be analyzed to count the number of times their amplitude reaches the preset amplitude threshold. If the number reaches the preset number, it is considered that the current first stimulation intensity can stably induce motor evoked potentials of sufficient intensity in the contralateral hand muscles, and the first stimulation intensity is determined as the first motor threshold. If the number of times the amplitude of the motor evoked potential reaches the preset amplitude threshold does not reach the preset number, that is, it does not meet the preset conditions, then the stimulation intensity needs to be adjusted.
[0114] When the motor evoked potential does not meet the preset conditions, a new stimulation intensity greater than the current first stimulation intensity (i.e., the first secondary intensity) can be determined, and this new stimulation intensity is called the second secondary intensity, and it is re-determined as the first stimulation intensity. For example, if the current first stimulation intensity is 40% of the maximum output intensity of the device and does not meet the preset conditions, the first stimulation intensity can be adjusted to 45%, and then the primary motor cortex is stimulated again with this new first stimulation intensity, and the motor evoked potential is recorded, and the above judgment process is repeated until the motor evoked potential meets the preset conditions.
[0115] Figure 2FIG. 1 is a block diagram of a device for determining the stimulation intensity of a target regulated cortex provided by an embodiment of the present application. Figure 2 As shown, the device may include:
[0116] A first threshold determination module 201 is used to obtain a first motor threshold of the primary motor cortex of the subject's head by using a transcranial magnetic stimulation experiment;
[0117] A model building module 202 is used to build an anisotropic conductivity head model corresponding to the subject's head based on the magnetic resonance imaging data of the subject's head;
[0118] A test area determination module 203 is used to determine a first test area corresponding to the primary motor cortex and a second test area corresponding to the target regulatory cortex in the anisotropic conductivity head model;
[0119] The electric field simulation module 204 is used to perform electric field simulation on the first test area and the second test area respectively by using the stimulation intensity value corresponding to the first motion threshold, so as to determine the first electric field value and the second electric field value generated in the first test area and the second test area;
[0120] A scaling factor determination module 205, configured to determine a scaling factor based on the first electric field value and the second electric field value;
[0121] The intensity determination module 206 is used to determine the target stimulation intensity of the target regulated cortex based on the scaling factor and the first motion threshold.
[0122] In some embodiments, the model building module 202 may be specifically used to:
[0123] acquiring magnetic resonance imaging data of the subject's head;
[0124] In the magnetic resonance imaging data, a plurality of tissue regions are identified;
[0125] Performing surface reconstruction on boundaries of multiple tissue regions to generate a head model including the multiple tissue regions;
[0126] Corresponding conductivity values are respectively configured for multiple tissue regions of the head model to generate an anisotropic conductivity head model, wherein different conductivity values corresponding to different tissue regions are different.
[0127] In some embodiments, the electric field simulation module 204 is specifically used to:
[0128] Determining a first primary electric field generated at a first test area, and a first secondary electric field, wherein the first secondary electric field is generated due to the difference in conductivity values between different tissue areas;
[0129] Based on the first primary electric field and the first secondary electric field, a first electric field value is obtained.
[0130] In some embodiments, the device further comprises:
[0131] A mesh partitioning module, used to partition the head model into a finite number of mesh cells;
[0132] In some embodiments, the electric field simulation module 204 is specifically used to:
[0133] For any grid cell of the first test area, a first primary electric field and a first secondary electric field generated at the grid cell are determined.
[0134] In some embodiments, the electric field simulation module 204 is specifically used to:
[0135] For any grid unit in the first test area, determining a first sub-electric field value corresponding to the grid unit based on the first primary electric field and the first secondary electric field;
[0136] Based on the number of grid cells included in the first test area, an average value of a plurality of first sub-electric field values is determined to obtain a first electric field value.
[0137] In some embodiments, the first threshold determination module 201 may be specifically implemented as follows:
[0138] Perform the following steps iteratively:
[0139] determining a first stimulus intensity;
[0140] The primary motor cortex was stimulated with the first stimulus intensity, and the motor evoked potentials of the contralateral hand muscles were recorded;
[0141] Determine whether the motor evoked potential meets the preset conditions. If so, determine the first stimulation intensity as the first motor threshold; if not, determine a second secondary intensity greater than the first secondary intensity, and determine the second secondary intensity as the first stimulation intensity until the motor evoked potential meets the preset conditions.
[0142] In some embodiments, the preset condition includes the number of times the amplitude value of the motor evoked potential reaches a preset amplitude threshold.
[0143] In some embodiments, the scaling factor determination module 205 is specifically configured to:
[0144] The ratio of the first electric field value to the second electric field value is used as a scaling factor.
[0145] In some embodiments, the strength determination module 206 is specifically configured to:
[0146] The scaling factor was multiplied by the first motor threshold to obtain the target stimulation intensity.
[0147] Figure 2The device for determining the stimulation intensity of the target regulated cortex can perform Figure 1 The implementation principle and technical effect of the method for determining the stimulation intensity of the target regulated cortex described in the embodiment are not described in detail. The specific manner in which each module and unit performs the operation of the device for determining the stimulation intensity of the target regulated cortex in the above embodiment has been described in detail in the embodiment of the method, and will not be described in detail here.
[0148] The present application also provides a computing device, such as Figure 3 As shown, the device may include a storage component and a processing component;
[0149] The storage component stores one or more computer instructions, wherein the one or more computer instructions are called and executed by the processing component to implement the method for determining the stimulation intensity of the target regulated cortex provided in an embodiment of the present application.
[0150] The input / output interface provides an interface between the processing component and the peripheral interface module, which may be an output device, an input device, etc. The communication component is configured to facilitate wired or wireless communication between the computing device and other devices.
[0151] The processing component may include one or more processors to execute computer instructions to complete all or part of the steps in the above method. Of course, the processing component may also be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors or other electronic components to perform the above method.
[0152] The storage component is configured to store various types of data to support operations at the terminal. The storage component can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.
[0153] The display component may be an electroluminescent (EL) element, a liquid crystal display or a micro display having a similar structure, or a retinal direct display or a similar laser scanning display.
[0154] It should be noted that the embodiments of the present application may involve the use of user data. In actual applications, user-specific personal data can be used in the scheme described herein within the scope permitted by applicable laws and regulations, subject to the requirements of applicable laws and regulations of the country where the user is located (for example, with the user's explicit consent, effective notification to the user, etc.).
[0155] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.
[0156] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.
[0157] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.
[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. A method for determining the stimulation intensity of a target regulated cortex, characterized in that: include: The first motor threshold of the primary motor cortex of the subject's head was obtained by transcranial magnetic stimulation experiment; Based on the magnetic resonance imaging data of the subject's head, constructing an anisotropic conductivity head model corresponding to the subject's head; Determining in the anisotropic conductivity head model a first test area corresponding to the primary motor cortex and a second test area corresponding to the target regulatory cortex; Using the stimulation intensity value corresponding to the first motion threshold, respectively performing electric field simulation on the first test area and the second test area to determine the first electric field value and the second electric field value generated in the first test area and the second test area; determining a scaling factor based on the first electric field value and the second electric field value; Based on the scaling factor and the first motion threshold, a target stimulation intensity of the target regulated cortex is determined.
2. The method according to claim 1, characterized in that The step of constructing an anisotropic conductivity head model corresponding to the subject's head based on the magnetic resonance imaging data of the subject's head comprises: Acquiring magnetic resonance imaging data of the subject's head; In the magnetic resonance imaging data, determining a plurality of tissue regions; Performing surface reconstruction on boundaries of the multiple tissue regions to generate a head model including the multiple tissue regions; Corresponding conductivity values are respectively configured for the multiple tissue regions of the head model to generate the anisotropic conductivity head model, wherein different conductivity values corresponding to different tissue regions are different.
3. The method according to claim 2, characterized in that The step of performing electric field simulation on the first test area by using the stimulation intensity value corresponding to the first motion threshold to determine a first electric field value generated at the first test area includes: Determining a first primary electric field generated at the first test area, and a first secondary electric field, wherein the first secondary electric field is generated due to the difference in conductivity values between different tissue areas; The first electric field value is obtained based on the first primary electric field and the first secondary electric field.
4. The method according to claim 2, characterized in that: After generating the head model including the plurality of tissue regions, the method further comprises: Dividing the head model into a finite number of grid cells; The determining of a first primary electric field generated at the first test area and a first secondary electric field comprises: For any grid unit of the first test area, a first primary electric field and a first secondary electric field generated at the grid unit are determined.
5. The method according to claim 4, characterized in that The obtaining the first electric field value based on the first primary electric field and the first secondary electric field comprises: For any grid unit of the first test area, determining a first sub-electric field value corresponding to the grid unit based on the first primary electric field and the first secondary electric field; Based on the number of grid units included in the first test area, an average value of a plurality of the first sub-electric field values is determined to obtain the first electric field value.
6. The method according to claim 1, characterized in that The method of obtaining the first motor threshold of the primary motor cortex of the subject's head by using a transcranial magnetic stimulation experiment comprises: Perform the following steps iteratively: determining a first stimulus intensity; Stimulating the primary motor cortex with the first stimulation intensity and recording motor evoked potentials of contralateral hand muscles; Determine whether the motor evoked potential meets a preset condition. If so, determine the first stimulation intensity as the first motion threshold; if not, determine a second secondary intensity greater than the first secondary intensity, and determine the second secondary intensity as the first stimulation intensity until the motor evoked potential meets the preset condition.
7. The method according to claim 6, characterized in that The preset condition includes the number of times the amplitude value of the motor evoked potential reaches a preset amplitude threshold.
8. The method according to claim 1, characterized in that: Determining a scaling factor based on the first electric field value and the second electric field value comprises: The ratio of the first electric field value to the second electric field value is used as the scaling factor.
9. The method according to claim 8, characterized in that Determining the target stimulation intensity of the target regulated cortex based on the scaling factor and the first motion threshold comprises: The scaling factor is multiplied by the first motion threshold to obtain the target stimulation intensity.
10. A computing device, characterized in that including a processing component and a storage component; The storage component stores one or more computer instructions; the one or more computer instructions are used to be called and executed by the processing component to implement the method for determining the stimulation intensity of the target regulated cortex as described in any one of claims 1 to 9.
11. A computer program product, characterized in that It comprises a computer program / instruction, which, when executed by a processing component, implements the method for determining the stimulation intensity of a target regulated cortex as described in any one of claims 1 to 9.