Closed-loop transcranial electrical stimulation system

Abstract

The invention relates to a closed-loop transcranial electrical stimulation system. The closed-loop transcranial electrical stimulation system comprises a neural signal sensing module, a real-time signal processing and control module and a transcranial electrical stimulation module, the real-time signal processing and control module is in communication connection with the neural signal sensing module and the transcranial electrical stimulation module; the real-time signal processing and control module is configured to execute the following operations: in a baseline calibration stage, selecting a part of signals from electroencephalogram signals collected by the neural signal sensing module, calculating and establishing average power of a target frequency band as a personal reference; calculating the average power of the signals corresponding to the one or more acquisition electrodes in the target frequency band, and setting the average power as a reference power value; the system monitors the power of a specific brain region in the frequency band in real time, and when the real-time power continuously exceeds a preset multiple of a reference value, electrical stimulation intervention with a fixed duration is automatically triggered. According to the system, through a closed-loop mode of intervention on demand, more accurate, efficient and safer nerve regulation and control are realized.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a closed-loop transcranial electrical stimulation system for electrically stimulating brain regions of patients. Background Technology

[0002] Transcranial electrical stimulation (tES), especially transcranial alternating current stimulation (tACS), has shown promise as a non-invasive neuromodulation technique in regulating brain rhythmic activity and intervening in neuropsychiatric disorders such as depression and anxiety. Existing tES protocols mostly employ an open-loop design, meaning that electrical stimulation of fixed duration and parameters is applied regardless of the patient's real-time brain state.

[0003] However, the above-mentioned stimulation methods have several shortcomings. For example, in some neuropsychiatric disorders (such as depression), specific pathological states (such as excessive rumination and cognitive inhibition) are closely related to abnormally increased alpha wave power in the prefrontal cortex, and this abnormal activity is often paroxysmal. Applying stimulation at unnecessary times is not only a waste of energy but may also fail to achieve the desired therapeutic effect. In addition, prolonged continuous stimulation may lead to adaptation in the brain, thereby reducing the intervention effect. Furthermore, unnecessary stimulation also increases the total charge exposure, which may lead to potential side effects such as skin discomfort.

[0004] Therefore, existing transcranial electrical stimulation (TCS) protocols are generally characterized by inconsistency and inefficiency. Different individuals, and even the same individual at different times, exhibit varying brain states, and fixed stimulation protocols cannot be adjusted to accommodate these dynamic changes. Summary of the Invention

[0005] The purpose of this application is to provide a transcranial electrical stimulation system that enables adaptive and personalized treatment through a closed-loop stimulation system for on-demand intervention. This system can solve the problems of inaccurate stimulation timing, lack of adaptability, and excessively high total stimulation dose in existing transcranial electrical stimulation techniques.

[0006] To this end, this application provides a closed-loop transcranial electrical stimulation (TCS) system, comprising: a neural signal sensing module for real-time acquisition of electroencephalogram (EEG) signals from a user's brain, the neural signal sensing module including a plurality of acquisition electrodes; a TCS module for applying electrical stimulation to the user's brain for a preset duration after receiving a stimulation initiation command; and a real-time signal processing and control module communicatively connected to the neural signal sensing module and the TCS module; wherein the real-time signal processing and control module is configured to perform the following operations: in a baseline calibration phase, selecting a portion of the EEG signals acquired by the neural signal sensing module, calculating the average power of the portion of the signals in a target frequency band, and setting the average power as a reference power value; in a real-time monitoring phase, continuously calculating the real-time power value of a specific brain region in the target frequency band; and comparing the real-time power value with the reference power value, and when the real-time power value continuously exceeds a preset trigger threshold for a preset duration, generating a stimulation initiation command to be sent to the TCS module.

[0007] In some embodiments, the target frequency band is the Alpha wave band.

[0008] In some embodiments, the specific brain region is the prefrontal cortex.

[0009] In some embodiments, the baseline calibration phase is scheduled to run for 10 minutes.

[0010] In some embodiments, the trigger threshold is twice the reference power value.

[0011] In some embodiments, the preset duration of the transcranial electrical stimulation module applying electrical stimulation is 3 minutes.

[0012] In some embodiments, the real-time signal processing and control module is further configured to automatically return to the real-time monitoring phase after the transcranial electrical stimulation module completes an electrical stimulation of a preset duration.

[0013] In some embodiments, the transcranial electrical stimulation module is a transcranial alternating current stimulation module.

[0014] In some embodiments, the stimulation frequency applied by the transcranial electrical stimulation module in the target frequency band is matched with the frequency of the target frequency band.

[0015] In some embodiments, the real-time signal processing and control module includes a stimulation control unit, which contains a timer.

[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: First, by activating stimulation only when specific neural activity characteristics requiring intervention are detected, the system ensures targeted stimulation, greatly improving the accuracy of intervention. Second, by establishing an individualized power baseline, the trigger threshold varies from person to person, fully considering individual differences and establishing a high degree of adaptability and personalization. Third, the system significantly reduces the total stimulation duration and total charge injection through intermittent, on-demand stimulation modes, reducing the risk of brain adaptation and improving the overall safety and comfort of the user. In addition, by concentrating stimulation energy on the time window most in need of intervention, it is expected to achieve the same or even better therapeutic effect with less total stimulation, thus improving efficiency. Attached Figure Description

[0017] Figure 1 This is a functional block diagram of a closed transcranial electrical stimulation system provided in an embodiment of this application.

[0018] Figure 2 This is a schematic diagram illustrating the usage process of the closed transcranial electrical stimulation system provided in this application embodiment.

[0019] Figure 3 This diagram illustrates a comparison of the electroencephalogram (EEG) power of the frontal scalp before and after using the closed-loop transcranial electrical stimulation system described in this application for a patient with depression. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0021] This application relates to a closed-loop transcranial electrical stimulation (TCS) system, the core of which is the establishment of a smart closed loop of "monitoring-decision-intervention". During operation, the system does not provide continuous stimulation, but rather monitors in real-time the power of specific brain regions (such as the prefrontal cortex) at specific frequency bands (such as alpha waves). Only when this real-time power value significantly exceeds a preset trigger threshold over a certain duration will the system automatically initiate an electrical stimulation intervention. This design ensures that treatment is only performed when specific neural activity characteristics requiring intervention are detected.

[0022] Reference Figure 1The illustration shows a closed-loop transcranial electrical stimulation system 100 provided according to the present application. The system 100 mainly includes three modules: a neural signal sensing module 201, a real-time signal processing and control module 202, and a transcranial electrical stimulation module 203.

[0023] The neural signal sensing module 201 is used to acquire multi-lead electroencephalogram (EEG) signals from the user's brain in real time. In one embodiment, the neural signal sensing module 201 is provided with several acquisition electrodes, such as an EEG electrode cap containing multiple acquisition electrodes. The positions of these acquisition electrodes are set to cover the entire brain, especially the prefrontal cortex region, such as the standard lead positions Fp1, Fp2, F7, F3, Fz, F4, and F8.

[0024] The real-time signal processing and control module 202 is the control center of system 100, running the core algorithm of the system. It is also communicatively connected to the neural signal sensing module 201 and the transcranial electrical stimulation module 203. In this application, the real-time signal processing and control module 202 is configured with a baseline calibration unit 202A, a real-time monitoring and decision-making unit 202B, and a stimulation control unit 202C, according to their different functions. The function of each unit is described below.

[0025] The baseline calibration unit 202A is responsible for executing a baseline calibration procedure during the initial startup of the system 100. Specifically, the baseline calibration unit 202A selects a subset of signals from the electroencephalogram (EEG) signals acquired by the neural signal sensing module 201, calculates the power of the target frequency band (e.g., the 8-13Hz alpha band) using methods such as Fast Fourier Transform (FFT) or wavelet transform, and calculates the average power of the selected acquisition electrodes, storing it as the user's personal baseline power value (P_baseline). The design scheme for selecting a subset of signals can be to select signals corresponding to one or more acquisition electrodes from all acquisition electrodes; these one or more acquisition electrodes can be preset in the program.

[0026] The real-time monitoring and decision-making unit 202B is used to enable system 100 to enter real-time monitoring mode after baseline calibration. In real-time monitoring mode, the real-time monitoring and decision-making unit 202B continuously receives EEG signals from specific leads (preset by the user or doctor) in specific brain regions (such as the prefrontal cortex) and calculates the real-time power value (P_realtime) of that region at a high temporal resolution (e.g., once per second). Simultaneously, it compares P_realtime with P_baseline. The built-in decision logic of the real-time monitoring and decision-making unit 202B is as follows: if the condition P_realtime > K * P_baseline (where K is a preset trigger coefficient, e.g., K = 2) is met for a preset duration (e.g., 3 consecutive seconds), the trigger condition is deemed met, and a start command is immediately sent to the stimulation control unit 202C.

[0027] Stimulation control unit 202C: This unit contains a timer. Upon receiving a start command, it immediately sends a command to the transcranial electrical stimulation module 203 to begin stimulation. Simultaneously, it starts a countdown of a preset duration (e.g., 3 minutes). When the countdown ends, it sends a command to module 203 to stop stimulation and notifies the monitoring and decision-making unit 202B to restart monitoring.

[0028] The transcranial electrical stimulation module 203 serves as the system's execution terminal and includes multiple stimulation electrodes. In a preferred embodiment, it is a transcranial alternating current stimulation (tACS) stimulator. However, the closed-loop control logic of this application is not limited to tACS; other forms of transcranial electrical stimulation techniques, such as transcranial direct current stimulation (tDCS) and transcranial random noise stimulation (tRNS), can also serve as the system's execution module, triggered and controlled by the application's control module based on the EEG power threshold. After receiving a start stimulation command from the real-time signal processing and control module 202, the transcranial electrical stimulation module 203 applies AC stimulation with preset parameters through stimulation electrodes placed in the prefrontal cortex region. For example, the stimulation parameters can be preset as follows: frequency of 10Hz (within the alpha band) and intensity of 1-2mA (peak-to-peak). Stimulation continues until a stop command is received.

[0029] Combination Figure 2 It lists a specific working process of the above system 100, including the following steps:

[0030] Step S1, Start: System 100 initialization.

[0031] Step S2: Perform baseline calibration: System 100 selects signals from one or more acquisition electrodes from the EEG data acquired by the neural signal sensing module 201.

[0032] Step S3: Calculate and store the reference power: The baseline calibration unit 202A of the real-time signal processing and control module 202 calculates the average Alpha power of one or more selected acquisition electrodes, denoted as P_baseline, and stores the value.

[0033] Step S4: Enter the real-time monitoring cycle: The real-time monitoring and decision-making unit 202B begins to continuously monitor the EEG signal in the prefrontal cortex region.

[0034] Step S5: Calculate the real-time Alpha power in the prefrontal cortex: The real-time monitoring and decision-making unit 202B calculates the current real-time power P_realtime.

[0035] Step S6, Decision Judgment: Real-time monitoring and decision-making unit 202B compares P_realtime with P_baseline. It determines whether the condition "P_realtime > 2 * P_baseline" persists for a preset period of time. If not true ("No"), the process returns to step S4 and continues monitoring. If true ("Yes"), the process proceeds to the next step.

[0036] Step S7: Start tACS stimulation: The real-time signal processing and control module 202 sends a start command to the transcranial electrical stimulation module 203.

[0037] Step S8, maintain stimulation for 3 minutes: the stimulation control unit 202C starts timing, and the transcranial electrical stimulation module 203 continuously outputs stimulation.

[0038] Step S9, Stop Stimulation: After the 3-minute timer ends, the real-time signal processing and control module 202 sends a stop command.

[0039] Step S10, Return to Monitoring: The system process returns to step S4 and restarts a new round of monitoring.

[0040] The execution of steps S2 and S3 above calculates and stores a personalized average EEG power as a baseline value for each user, and the threshold for triggering stimulation is set based on that user's personal baseline value. This allows the system to fully consider individual differences during operation, enabling the treatment plan to be adaptive, solving the problem of lack of personalization in traditional fixed-parameter plans, and improving the precision of intervention.

[0041] The execution of steps S4-S9 above allows the system to automatically stop stimulation and return to real-time monitoring after completing a preset duration of stimulation, forming a cycle. This on-demand, intermittent stimulation mode, compared to traditional long-duration continuous stimulation, can significantly reduce the total stimulation duration and the total amount of charge injected into the brain, thereby reducing the risk of the brain developing adaptation and improving user safety and tolerance.

[0042] The execution of the above steps S1-S10 enables the closed-loop transcranial electrical stimulation system 100 to concentrate stimulation energy on the time window when intervention is most needed (i.e. when the brain exhibits a specific pathological state), thereby achieving the same or even better therapeutic effect as traditional methods with less total stimulation, thus improving intervention efficiency.

[0043] See Figure 3 This is a comparative diagram of the spectral power of the scalp EEG in the frontal region of a patient with depression before and after the first 40-minute closed-loop transcranial electrical stimulation (EEG) with a 10 Hz, 1.6 mA sine wave, using the closed-loop EEG system designed in this application. It can be seen that after treatment, the power of the scalp EEG in the frontal region in the alpha band significantly decreased (the red area decreased, indicating a power reduction).

[0044] While exemplary embodiments of the present invention have been shown and described above, those skilled in the art will understand that various changes and modifications can be made, and equivalent forms can be substituted for elements therein without departing from the actual scope of the invention. Furthermore, many modifications can be made to adapt to specific situations and the teachings of the invention without departing from its central scope. Therefore, all embodiments falling within the scope of the claims of this invention are within the protection scope of this invention.

Claims

1. A closed-loop transcranial electrical stimulation system, comprising: A neural signal sensing module is used to collect electroencephalogram (EEG) signals from a user's brain in real time. The neural signal sensing module includes several acquisition electrodes. The transcranial electrical stimulation module is used to apply electrical stimulation to the user's brain for a preset duration after receiving a stimulation activation command; and A real-time signal processing and control module is communicatively connected to the neural signal sensing module and the transcranial electrical stimulation module; characterized in that the real-time signal processing and control module is configured to perform the following operations: In a baseline calibration phase, a portion of the EEG signals acquired by the neural signal sensing module is selected, the average power of the portion of the signals in the target frequency band is calculated, and the average power is set as the reference power value. During a real-time monitoring phase, the real-time power values ​​of specific brain regions in the target frequency band are continuously calculated; and The real-time power value is compared with the reference power value. When the real-time power value exceeds a preset trigger threshold for a preset duration, a command to initiate stimulation is generated and sent to the transcranial electrical stimulation module.

2. The closed-loop transcranial electrical stimulation system according to claim 1, characterized in that, The target frequency band is the Alpha wave band.

3. The closed-loop transcranial electrical stimulation system according to claim 1, characterized in that, The specific brain region mentioned is the prefrontal cortex.

4. The closed-loop transcranial electrical stimulation system according to claim 1, characterized in that, The preset duration for the baseline calibration phase is 10 minutes.

5. The closed-loop transcranial electrical stimulation system according to claim 1, characterized in that, The trigger threshold is twice the reference power value.

6. The closed-loop transcranial electrical stimulation system according to claim 1, characterized in that, The preset duration of the transcranial electrical stimulation module is 3 minutes.

7. The closed-loop transcranial electrical stimulation system according to claim 1, characterized in that, The real-time signal processing and control module is also configured to automatically return to the real-time monitoring stage after the transcranial electrical stimulation module completes an electrical stimulation of a preset duration.

8. The closed-loop transcranial electrical stimulation system according to claim 1, characterized in that, The transcranial electrical stimulation module is a transcranial alternating current stimulation module.

9. The closed-loop transcranial electrical stimulation system according to claim 1, characterized in that, The transcranial electrical stimulation module applies stimulation at a frequency that matches the frequency of the target frequency band.

10. The closed-loop transcranial electrical stimulation system according to claim 1, characterized in that, The real-time signal processing and control module includes a stimulation control unit, which contains a timer.

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