A precise focusing method for cortical targets in brain mapping

Abstract

This invention discloses a method for precise focusing of cortical targets in brain atlases, comprising the following steps: segmenting the MRI image of the target to obtain a gray matter template and a scalp template; selecting a target point and mapping the target point from the gray matter template to the scalp template to obtain the center position of the corresponding central electrode on the scalp; and optimizing the parameters of the peripheral and central electrodes based on the center position of the central electrode to achieve precise focusing of the target point. This invention first segments the MRI image to obtain a gray matter template, then maps the target point on the gray matter template to obtain the center position of the corresponding central electrode on the scalp. Based on this position, the distance between the peripheral and central electrodes, the current magnitude, and the electrode size are optimized, enabling precise focusing and control of the target point with a smaller stimulation electrode.

Description

Technical Field

[0001] This invention belongs to the technical field of alternating current stimulation for neuromodulation, and in particular relates to a method for precise focusing of cortical targets in brain atlases. Background Technology

[0002] Transcranial electrical stimulation (TCS) is a mature and convenient neuromodulation method. It modulates specific brain regions by applying low-intensity current (generally less than 2mA) to the scalp. In clinical applications, it can be used to modulate neuropsychiatric diseases (Parkinson's disease, depression, Alzheimer's disease, etc.). For healthy individuals, it can improve working memory, cognitive ability, and motor ability. It has the advantages of being non-invasive, non-addictive, and having few side effects.

[0003] Brain mapping is a map of the human brain that provides navigation and positioning for neuromodulation. With the continuous improvement of technology, brain mapping has become increasingly refined and individualized, allowing for the selection of specific brain regions to be stimulated according to the needs of regulation, and the construction of personalized and precise regulation plans, which puts forward a high degree of focus for neuromodulation.

[0004] The emergence of high-precision transcranial electrical stimulation (HD-TES) has improved the focusing of traditional transcranial electrical stimulation. For HD-TES, improving focusing requires a smaller electrode distance and a smaller electrode size. However, when the current magnitude is the same, as the electrode size gradually decreases, the increase in current density increases the pain of stimulation and limits the focusing range of transcranial electrical stimulation.

[0005] Temporal interference electrical stimulation (TIS) achieves neuromodulation through an envelope field generated by two high-frequency carrier waves with a difference frequency. The high-frequency current's penetrability through the skull reduces current dissipation along the path from the scalp to the cerebral cortex. Compared to low-frequency current, high-frequency current has lower pain sensitivity and better pain tolerance at the same current density, making the use of small electrodes possible during TIS. However, the envelope field of TIS varies greatly between individuals, requiring individualized localization and optimization of multiple electrode arrays, which is time-consuming and difficult to apply. Summary of the Invention

[0006] The purpose of this invention is to provide a method for precise focusing of cortical targets in brain atlases. After constructing an individualized brain atlas of the subject, based on the selected regulatory targets, the MRI image is first segmented to obtain a gray matter template. Based on the stimulation targets on the gray matter template, the center position of the corresponding central electrode on the scalp is mapped. Based on this position, the distance between the peripheral electrode and the central electrode, the current magnitude, and the electrode size are optimized to achieve precise focusing and regulation of the target, thus solving the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides a method for precise focusing of cortical targets in brain atlases, comprising the following steps:

[0008] The MRI images of the controlled object were segmented to obtain gray matter templates and scalp templates;

[0009] Select a target point and map the target point from the gray matter template to the scalp template to obtain the center position of the corresponding central electrode on the scalp;

[0010] Based on the center position of the central electrode, the parameters of the peripheral electrode and the central electrode are optimized to achieve precise focusing of the target.

[0011] Optionally, the process prior to selecting a target includes: constructing a personalized brain atlas based on functional magnetic resonance imaging of the regulated object, and selecting a target on the personalized brain atlas based on the regulated target.

[0012] Optionally, the process of obtaining the center position of the corresponding central electrode on the scalp includes: mapping the normal vector on the gray matter template where the target point is located onto the scalp template to obtain the center position of the corresponding central electrode on the scalp.

[0013] Optionally, the process before optimizing the parameters of the peripheral and central electrodes includes: segmenting the structural MRI images based on a Gaussian mixture model to obtain brain tissue templates of the scalp, skull, cerebrospinal fluid, gray matter, white matter, and ventricles, and recombining several brain tissue templates to construct a three-dimensional brain tissue structure template.

[0014] Optionally, the process of optimizing the parameters of the peripheral and central electrodes includes: after fixing the center position of the central electrode, constructing an individualized model based on the three-dimensional brain tissue structure template, using the finite element method to solve the Laplace equation to simulate the intracranial electric field during electrical stimulation, and varying the size of the central and peripheral electrodes, the distance between the central and peripheral electrodes, and the magnitude of the stimulation current. By constraining the target location by maximizing the amplitude of the envelope field at the target location and minimizing the amplitude of the outer envelope field at the target location, precise focusing of the target location is achieved.

[0015] Optionally, either the first stimulation method or the second stimulation method may be used during the electrical stimulation process;

[0016] The structure of the first stimulation method includes a first channel and a second channel, each of which includes a circular first central electrode and a ring electrode; wherein the first channel and the second channel share the first central electrode;

[0017] The structure of the second stimulation mode includes a third channel and a fourth channel. Each of the third and fourth channels includes a circular second central electrode and several circular peripheral electrodes. The centers of the peripheral electrodes are on a circle and are evenly distributed. The third and fourth channels share the second central electrode.

[0018] The sum of the currents of the first center electrode and the second center electrode is less than the safe current.

[0019] Optionally, an envelope field is generated during stimulation, the frequency of which is the frequency difference between the two channels of the first stimulation mode or the second stimulation mode.

[0020] Optionally, both channels of the first stimulation mode or the second stimulation mode are dual AC outputs, wherein the currents of the two outputs are inverted and the sum of the currents is 0.

[0021] The technical effects of this invention are as follows:

[0022] This invention discloses a method for precise focusing of cortical targets in brain atlases. After constructing an individualized brain atlas of the subject, based on the selected regulatory targets, the MRI image is first segmented to obtain a gray matter template. Based on the stimulation targets on the gray matter template, the center position of the corresponding central electrode on the scalp is obtained by mapping. Based on this position, the distance between the peripheral electrode and the central electrode, the current magnitude, and the electrode size are optimized, which can achieve precise focusing and regulation of the target with smaller stimulation electrodes. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0024] Figure 1 This is a schematic diagram of the high-precision time-interference electrical stimulation method in an embodiment of the present invention;

[0025] Figure 2 This is a flowchart illustrating the process of a precise focusing method for cortical targets in brain maps according to an embodiment of the present invention.

[0026] Figure 3 This is an overall flowchart of the method for precise focusing of cortical targets in brain maps according to an embodiment of the present invention. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0029] Example 1

[0030] This embodiment integrates high-precision transcranial electrical stimulation (TCS) with time-disrupted electrical stimulation (TDPS) to provide a precise focusing method for cortical targets in brain mapping. It combines the focusing ability of high-precision TCS with the skull penetration and pain tolerance of TDPS, achieving precise focusing of cortical targets by maximizing the envelope field beneath the central electrode. The method includes the following steps:

[0031] S1: Acquire functional and structural MRI data of the subjects subjected to electrical stimulation to construct individualized brain atlases and brain tissue structure templates;

[0032] S2: Based on the constructed individualized brain atlas, select electrical stimulation targets and frequencies according to the regulatory objectives;

[0033] S3: After the target point for electrical stimulation modulation is determined, the target point is mapped from the gray matter to the scalp based on the gray matter template and the scalp template obtained by segmentation, and the center position of the designed high-precision time-interference electrical stimulation center electrode is determined.

[0034] S4: Based on the center position of the central electrode, optimize three parameters—distance between the outer peripheral electrode and the central electrode, current magnitude, and electrode size—through finite element simulation to achieve precise focusing of the target point;

[0035] Furthermore, the structure of the high-precision time-interference electrical stimulation method in this embodiment consists of a central electrode and an outer peripheral electrode, wherein the central electrode is circular and the outer peripheral electrode is ring-shaped or circular.

[0036] Furthermore, the high-precision time-interference electrical stimulation method in this embodiment is divided into two stimulation modes according to the electrode combination: HD-TIS-Ring and HD-TIS-4*1. HD-TIS-Ring is input through two channels, each channel consists of a set of electrodes, and each set of electrodes includes a circular central electrode and a ring electrode. HD-TIS-4*1 is input through two channels, each channel consists of a set of electrodes, and each set of electrodes includes a circular central electrode and four circular peripheral electrodes. The centers of the four peripheral electrodes are on a circle and are evenly distributed.

[0037] Furthermore, in the two stimulation modes of the high-precision time-interference electrical stimulation method, the two channels share a central electrode.

[0038] Furthermore, the sum of the currents at the two center electrodes is less than the safe current (generally below 2mA).

[0039] Furthermore, the current output of the high-precision time-interference electrical stimulation method is alternating current, the carrier frequency is f, and the difference frequency is Δf. For the two stimulation methods, during the stimulation process, the frequency of one channel is f, and the frequency of the other channel is f+Δf, generating an envelope field with a frequency of Δf.

[0040] Furthermore, each channel of both stimulation methods has two AC outputs, with the currents of the two outputs inverted and the sum of the currents being 0.

[0041] Specifically, the HD-TIS-4*1 electrode method is used during electrical stimulation, such as... Figure 1 As shown, an alternating current of I1 with frequency f is applied to the center electrode of channel 1, and the current at the four outer electrodes of channel 1 is -I1 / 4. An alternating current of I2 with frequency f+Δf is applied to the center electrode of channel 2, and the current at the four outer electrodes of channel 2 is -I2 / 4, where I1+I2<=2mA. The formula for calculating the envelope is shown below:

[0042]

[0043] The workflow for achieving precise target focusing is as follows: Figure 2 As shown, the overall process is as follows: Figure 3 As shown, in step S1, the acquired structured imaging data (sMRI) is segmented based on a Gaussian mixture model to obtain brain tissue templates of the scalp, skull, cerebrospinal fluid, gray matter, white matter, and ventricles, and reconstructed into a three-dimensional brain tissue structure; and individualized brain atlases are generated from the acquired functional imaging data (fMRI).

[0044] In step S2, the electrical stimulation target point and frequency are selected based on the individual brain map of the target person to achieve individualized regulation.

[0045] In step S3, after determining the stimulation target, the target is mapped onto the scalp using the normal vector of the gray matter location, thus obtaining the corresponding position on the scalp. This position is the center position of the high-precision focused transcranial electrical stimulation central electrode.

[0046] In step S4, after the central electrode is fixed, an individualized model is constructed using the brain tissue structure reconstructed in step S1. The finite element method is used to simulate the intracranial electric field during electrical stimulation by solving the Laplace equation. By changing the size of the central electrode and the peripheral electrode, the distance between the central electrode and the peripheral electrode, and the magnitude of the stimulation current, as shown in the following formula, the amplitude of the envelope field at the target location is maximized and the amplitude of the outer envelope field at the target location is minimized, thereby achieving precise focusing of the target location.

[0047]

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0049] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for precise focusing of cortical targets in brain atlases, characterized in that, Includes the following steps: The MRI images of the controlled object were segmented to obtain gray matter templates and scalp templates; Select a target point and map the target point from the gray matter template to the scalp template to obtain the center position of the corresponding central electrode on the scalp; Based on the center position of the central electrode, the parameters of the peripheral electrode and the central electrode are optimized to achieve precise focusing of the target. The process before optimizing the parameters of the peripheral and central electrodes includes: segmenting the structural MRI images based on the Gaussian mixture model to obtain brain tissue templates of the scalp, skull, cerebrospinal fluid, gray matter, white matter, and ventricles, and recombining several brain tissue templates to construct a three-dimensional brain tissue structure template; The process of optimizing the parameters of the peripheral and central electrodes includes: after fixing the center position of the central electrode, constructing an individualized model based on the three-dimensional brain tissue structure template, using the finite element method to solve the Laplace equation to simulate the intracranial electric field during electrical stimulation, and varying the size of the central and peripheral electrodes, the distance between the central and peripheral electrodes, and the magnitude of the stimulation current. By constraining the target point location by maximizing the amplitude of the envelope field and minimizing the amplitude of the outer envelope field, precise focusing of the target point location is achieved.

2. The method for precise focusing of cortical targets in brain atlases according to claim 1, characterized in that, The process prior to target selection includes: constructing a personalized brain atlas based on functional magnetic resonance imaging of the regulated object, and selecting target points on the personalized brain atlas based on the regulated target.

3. The method for precise focusing of cortical targets in brain atlases according to claim 1, characterized in that, The process of obtaining the center position of the corresponding central electrode on the scalp includes: mapping the normal vector on the gray matter template where the target point is located onto the scalp template to obtain the center position of the corresponding central electrode on the scalp.

4. The method for precise focusing of cortical targets in brain atlases according to claim 1, characterized in that, During electrical stimulation, either the first or second stimulation method is used; The structure of the first stimulation method includes a first channel and a second channel, each of which includes a circular first central electrode and a ring electrode; wherein the first channel and the second channel share the first central electrode; The structure of the second stimulation mode includes a third channel and a fourth channel. Each of the third and fourth channels includes a circular second central electrode and several circular peripheral electrodes. The centers of the peripheral electrodes are on a circle and are evenly distributed. The third and fourth channels share the second central electrode. The sum of the currents of the first center electrode and the second center electrode is less than the safe current.

5. The method for precise focusing of cortical targets in brain atlases according to claim 1, characterized in that, An envelope field is generated during stimulation, and the frequency of the envelope field is the frequency difference between the two channels of the first stimulation mode or the second stimulation mode.

6. The method for precise focusing of cortical targets in brain atlases according to claim 5, characterized in that, Both channels of the first or second stimulation method have two AC outputs, with the currents of the two outputs reversed and the sum of the currents being 0.

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