A closed-loop EEG control method and system

Abstract

The present application provides a closed-loop EEG control method and system, the method comprising the following steps: receiving an EEG signal of an experimental subject; preprocessing the EEG signal to obtain a preprocessed EEG signal; calculating and processing the preprocessed EEG signal to obtain a θ rhythm EEG signal and an EEG characteristic value; processing the θ rhythm EEG signal and the EEG characteristic value to obtain an ultrasonic stimulation parameter and a θ rhythm setting stimulation phase; according to the ultrasonic stimulation parameter and the θ rhythm setting stimulation phase, ultrasonic stimulation is emitted to the experimental subject to perform EEG control. The present application collects and analyzes the EEG signal of the experimental subject in real time, and uses a closed-loop ultrasonic stimulation technology to achieve EEG control of the experimental subject using the EEG θ rhythm as a marker.

Description

Technical Field

[0001] The present application relates to the technical field of ultrasonic stimulation neural regulation, and in particular to a closed-loop EEG regulation method and system. Background Art

[0002] Brain nerve regulation technology is an important method that uses external technical means such as light, magnetism, electricity, ultrasound, or chemistry to change the endogenous neural signal transmission in the brain, thereby causing changes in brain function. Ultrasonic neuroregulation is a new type of brain stimulation technology. Compared with other traditional electrical, magnetic, and optical neurostimulation technologies, it has the advantages of strong directionality, deep penetration, accurate target control, and non-invasiveness. Therefore, in recent years, ultrasonic non-invasive brain nerve regulation technology has attracted much attention from scholars in the field of neuroscience.

[0003] Ultrasound, as a neuromodulation technology, can be widely used in neuromodulation research in cells, rodents, non-human primates and humans, and is an ideal neuromodulation tool. However, unlike electrical stimulation neuromodulation technology, the use of closed-loop ultrasound systems has rarely appeared in previous transcranial ultrasound stimulation studies, and the stimulation parameters cannot be changed in real time according to the characteristics of the subject during the stimulation process.

[0004] In addition, a very important rhythm in the EEG of mammals is the theta rhythm, which is generated by the local interaction between hippocampal interneurons and pyramidal neurons. The theta rhythm plays a key role in multiple types of learning and memory processes, and is also crucial for regulating synaptic plasticity. However, existing closed-loop EEG control methods do not take the theta rhythm into account. To this end, the present application proposes a closed-loop EEG control method and system. Summary of the invention

[0005] The purpose of this application is to provide a closed-loop EEG control method and system to address the above problems.

[0006] In a first aspect, the present application provides a closed-loop EEG control method, the method comprising the following steps:

[0007] Receive EEG signals from the subject;

[0008] Preprocessing the EEG signal to obtain a preprocessed EEG signal;

[0009] Calculating and processing the preprocessed EEG signal to obtain a theta rhythm EEG signal and an EEG characteristic value;

[0010] Processing the theta rhythm electroencephalogram signal and the electroencephalogram characteristic value to obtain ultrasonic stimulation parameters and theta rhythm stimulation phase setting;

[0011] The stimulation phase is set according to the ultrasonic stimulation parameters and the theta rhythm, and ultrasonic stimulation is given to the experimental subject to perform EEG regulation.

[0012] According to the technical solution provided in some embodiments of the present application, the EEG signal is preprocessed to obtain a preprocessed EEG signal, which specifically includes the following steps:

[0013] The EEG signal is downsampled, subjected to 50 Hz notch denoising and 4-200 Hz filtering to obtain a preprocessed EEG signal.

[0014] According to the technical solution provided in some embodiments of the present application, the pre-processed EEG signal is calculated and processed to obtain the θ rhythm EEG signal and the EEG characteristic value, which specifically includes the following steps:

[0015] Performing 4-8 Hz filtering on the preprocessed EEG signal to obtain a theta rhythm EEG signal;

[0016] The preprocessed EEG signal and the θ rhythm EEG signal are processed by calculation to obtain the EEG characteristic value.

[0017] According to the technical solution provided in some embodiments of the present application, the theta rhythm EEG signal and the EEG characteristic value are processed to obtain the ultrasonic stimulation parameters and the theta rhythm stimulation phase setting, which specifically includes the following steps:

[0018] Calculating the error between the EEG characteristic value and the preset expected value, and obtaining the ultrasound control parameter according to the control strategy;

[0019] Calculating the theta rhythm phase of the theta rhythm electroencephalogram signal by using Hilbol transform;

[0020] The stimulation phase is set according to the theta rhythm phase and the theta rhythm of the theta rhythm electroencephalogram signal predicted by the prediction model.

[0021] According to the technical solution provided by certain embodiments of the present application, the control strategy is a generalized minimum variance control strategy.

[0022] According to the technical solution provided in some embodiments of the present application, the stimulation phase is set according to the ultrasonic stimulation parameters and the theta rhythm, and ultrasonic stimulation is given to the experimental subject to perform EEG regulation, which specifically includes the following steps:

[0023] Generate a first control waveform signal according to the ultrasound stimulation parameter and the theta rhythm setting stimulation phase;

[0024] amplifying and processing the first control waveform signal to obtain a second control waveform signal;

[0025] enabling the second control waveform signal to be output as an ultrasonic signal;

[0026] The ultrasonic signal is confined within a set spatial range and emitted to the experimental object.

[0027] In a second aspect, the present application provides a closed-loop EEG control system of the above-mentioned closed-loop EEG control method, comprising:

[0028] A processing module, configured to receive and pre-process the EEG signal of the experimental subject to obtain a pre-processed EEG signal, and further configured to calculate and process the pre-processed EEG signal to obtain a theta rhythm EEG signal and an EEG characteristic value;

[0029] A control module configured to process the theta rhythm EEG signal and the EEG characteristic value to obtain ultrasound stimulation parameters and theta rhythm stimulation phase setting;

[0030] The ultrasonic stimulation module is configured to set the stimulation phase according to the ultrasonic stimulation parameters and the theta rhythm, and to emit ultrasonic stimulation to the experimental subject to perform brain electrical regulation.

[0031] According to the technical solutions provided in some embodiments of the present application, the processing module includes:

[0032] A preprocessing module is configured to receive the EEG signal, and perform downsampling, notch denoising and filtering on the EEG signal to obtain a preprocessed EEG signal;

[0033] a theta rhythm electroencephalogram calculation module, configured to perform 4-8 Hz filtering on the preprocessed electroencephalogram signal to obtain a theta rhythm electroencephalogram signal;

[0034] The EEG characteristic value calculation module is configured to calculate and process the preprocessed EEG signal and the θ rhythm EEG signal to obtain the EEG characteristic value.

[0035] According to the technical solutions provided in some embodiments of the present application, the control module includes:

[0036] a theta rhythm phase prediction module, configured to calculate the theta rhythm phase of the theta rhythm electroencephalogram signal by using a Hilbolt transform, and further configured to predict the theta rhythm setting stimulation phase of the theta rhythm electroencephalogram signal according to the theta rhythm phase and a prediction model;

[0037] The ultrasonic control parameter calculation module is configured to calculate the error between the EEG characteristic value and a preset expected value, and obtain the ultrasonic control parameter according to the control strategy.

[0038] According to the technical solutions provided in some embodiments of the present application, the ultrasonic stimulation module includes:

[0039] A signal generating module configured to generate a first control waveform signal according to the ultrasonic stimulation parameter and the theta rhythm setting stimulation phase;

[0040] A power amplification module, configured to amplify and process the first control waveform signal to obtain a second control waveform signal;

[0041] An ultrasonic transducer module, configured to enable the second control waveform signal to be output as an ultrasonic signal;

[0042] The collimation module is configured to limit the ultrasonic signal within a set spatial range and transmit it to the experimental object.

[0043] Compared with the prior art, the present application has the following beneficial effects: the closed-loop EEG control method provided by the present application includes: receiving EEG signals of experimental subjects; preprocessing the EEG signals to obtain preprocessed EEG signals; calculating and processing the preprocessed EEG signals to obtain θ rhythm EEG signals and EEG characteristic values; processing the θ rhythm EEG signals and the EEG characteristic values ​​to obtain ultrasonic stimulation parameters and θ rhythm setting stimulation phase; according to the ultrasonic stimulation parameters and the θ rhythm setting stimulation phase, ultrasonic stimulation is emitted to the experimental subject to perform EEG control; the present application collects and analyzes the EEG signals of experimental subjects in real time, and uses closed-loop ultrasonic stimulation technology to achieve EEG control of the experimental subjects using the EEG θ rhythm as a marker.

[0044] The frequency band of the theta rhythm is 4-8Hz, and the period is 125-250ms, which is convenient for ensuring the stimulation accuracy in the EEG closed-loop control when there is a ms-level device operation delay. The EEG theta rhythm acts on the learning and memory process. Using the EEG theta rhythm as a marker for closed-loop EEG control can further regulate the neural action mechanisms and plastic neural pathways related to learning and memory, which is conducive to the study of improving the learning, memory and cognitive functions of experimental subjects. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of the structure of a closed-loop EEG control system provided in Example 1 of the present application;

[0046] Figure 2 A flow chart of a closed-loop EEG control method provided in Example 2 of the present application;

[0047] Figure 3 for Figure 2 Specific flow chart of step S3;

[0048] Figure 4 for Figure 2 Specific flow chart of step S4;

[0049] Figure 5 for Figure 2 Specific flow chart of step S5 in FIG. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the technical solution of the present application, the present application is described in detail below in conjunction with the accompanying drawings. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present application.

[0051] Example 1

[0052] Please refer to Figure 1 This embodiment provides a closed-loop EEG regulation system, which includes an acquisition module, a processing module, a control module and an ultrasonic stimulation module.

[0053] The acquisition module is connected to the experimental subject and is used to acquire the EEG signal of the experimental subject in real time; wherein the experimental subject is set as a small black mouse commonly used in laboratory experiments; the acquisition module includes EEG electrodes and a neural signal processor; the EEG electrodes include three channels, one of which is a tungsten microelectrode inserted in the CA1 area of ​​the hippocampus under the skull of the experimental subject to record the EEG of this brain area, and the other two electrodes are inserted in the nasal bone of the experimental subject as a reference electrode and a ground electrode; the neural signal processor is connected to the EEG electrodes, and is configured to convert the EEG signals into corresponding digital signals, and send the converted digital signals to the EEG signal processing module.

[0054] In this embodiment, the neural signal processor may be an ApolloⅡ neural signal processor from Bio-Signal Technologies, with a sampling frequency of 30 kHz, and connected to a PC via a USB interface.

[0055] The processing module is connected to the acquisition module, and is used to receive the EEG signals of the experimental subject acquired by the acquisition module, and pre-process the EEG signals to obtain pre-processed EEG signals, and is also configured to calculate and process the pre-processed EEG signals to obtain θ rhythm EEG signals and EEG characteristic values.

[0056] Specifically, the processing module includes: a preprocessing module, a θ rhythm EEG calculation module and an EEG characteristic value calculation module.

[0057] The preprocessing module is connected to the acquisition module, configured to receive the EEG signal, and downsample, 50Hz notch denoising and 4-200Hz filtering the EEG signal to obtain a preprocessed EEG signal, and is also configured to send the preprocessed EEG signal to the θ rhythm EEG calculation module and the EEG characteristic value calculation module.

[0058] The θ rhythm EEG calculation module is configured to perform 4-8 Hz filtering on the preprocessed EEG signal to obtain a θ rhythm EEG signal, and is also configured to send the θ rhythm EEG signal to the EEG characteristic value calculation module and the control module.

[0059] The EEG characteristic value calculation module is configured to calculate and process the preprocessed EEG signal and the θ rhythm EEG signal to obtain the EEG characteristic value, and is also configured to send the EEG characteristic value to the control module. The EEG characteristic value includes the absolute power of the preprocessed EEG signal, the relative power of the θ rhythm EEG signal relative to the preprocessed EEG signal, sample entropy, etc.

[0060] The control module is configured to process the θ rhythm EEG signal and the EEG characteristic value to obtain ultrasound stimulation parameters and θ rhythm stimulation phase setting.

[0061] Specifically, the control module includes: a theta rhythm phase prediction module and an ultrasound control parameter calculation module.

[0062] The ultrasound control parameter calculation module is connected to the EEG characteristic calculation module, and is configured to calculate the error between the EEG characteristic value and the preset expected value, and obtain the ultrasound control parameter according to the control strategy, and is also configured to send the ultrasound control parameter to the ultrasound stimulation module. The ultrasound control parameters include parameters such as ultrasound size and duration.

[0063] The θ rhythm phase prediction module is connected to the θ rhythm EEG calculation module, and is configured to receive the θ rhythm EEG signal and calculate the θ rhythm phase of the θ rhythm EEG signal using the Hilboer transform. It is also configured to predict the time of setting the stimulation phase of the θ rhythm through a prediction model to obtain the ultrasonic stimulation time, and send the ultrasonic output instruction to the ultrasonic stimulation module according to the ultrasonic stimulation time; the θ rhythm prediction model can predict the θ rhythm phase for a period of time in the future based on the historical EEG θ rhythm.

[0064] The control strategy can adjust the ultrasound parameters according to the error between the current EEG characteristic value and the preset expected value, so as to reduce or even eliminate the error. In this embodiment, the control strategy uses a generalized minimum variance control strategy, the θ rhythm phase prediction model is an AR model, and the θ rhythm sets the stimulation phase to the peak.

[0065] In this embodiment, the processing module and the control module are implemented by a C++ program and a MATLAB program in a PC respectively, and the data transmission between the C++ program and the MATLAB program is implemented by a UDP data packet.

[0066] The ultrasonic stimulation module is configured to set a stimulation phase according to the ultrasonic stimulation parameters and the theta rhythm, and to emit ultrasonic stimulation to the experimental subject to perform EEG regulation.

[0067] Specifically, the ultrasonic stimulation module includes: a signal generation module, a power amplification module, an ultrasonic transducer module and a collimation module.

[0068] The signal generating module is configured to receive the output instruction sent by the theta rhythm phase prediction module and the ultrasound stimulation parameter sent by the control parameter calculation module, and generate a first control waveform signal.

[0069] The signal generating module is a function / arbitrary waveform generator that can remotely receive parameters such as ultrasonic frequency, pulse repetition frequency, number of pulse cycles, pulse train length, pulse train interval, number of train cycles, and start stimulation time in real time; in this embodiment, the signal generating module can optionally adopt a RIGOL brand DG2080 model function / arbitrary waveform generator, which is connected to a PC via a USB interface, outputs the signal to the ultrasonic transducer via a BNC line, and the received control instructions are sent by a MATLAB program.

[0070] The power amplification module is configured to amplify the first control waveform signal to obtain a second control waveform signal, and send the second control waveform signal to the super energy conversion module.

[0071] In this embodiment, the power amplification module is implemented by a radio frequency amplifier. In this preferred embodiment, the power amplifier model is a 240L ENI linear power amplifier.

[0072] The ultrasonic transducer module is configured to enable the second control waveform signal to be output as an ultrasonic signal and is connected to the collimation module; the ultrasonic transducer module is an ultrasonic transducer, which is an active device that can convert electrical power into mechanical power output, that is, a device that converts electrical energy into sound energy, and this process has only very small power loss (ultrasound is a mechanical wave).

[0073] In this embodiment, the ultrasonic transducer generates ultrasound, the center frequency of which is set to 500 kHz, and an Olympus ultrasonic transducer with a diameter of 31 mm, model V301-SU, is selected.

[0074] The collimation module is fixedly connected to the output end of the ultrasonic transducer, and is configured to limit the ultrasonic signal within a set spatial range and transmit it to the experimental object, while reducing the attenuation of ultrasound during propagation by filling it with coupling liquid; in this embodiment, the collimation module is a collimator.

[0075] Example 2

[0076] This embodiment provides a closed-loop EEG control method using the closed-loop EEG control system described in Embodiment 1. Figure 2is a flow chart of the method, and the method comprises the following steps:

[0077] S1. Receive EEG signals from the subject.

[0078] In this embodiment, the experimental subjects are small black mice commonly used in laboratory experiments.

[0079] S2. Preprocess the EEG signal to obtain a preprocessed EEG signal.

[0080] This step specifically includes: performing downsampling, 50 Hz notch denoising and 4-200 Hz filtering on the EEG signal to obtain a preprocessed EEG signal.

[0081] S3. Calculate and process the preprocessed EEG signal to obtain a θ rhythm EEG signal and EEG characteristic values.

[0082] like Figure 3 As shown, this step specifically includes:

[0083] S31, performing 4-8 Hz filtering on the preprocessed EEG signal to obtain a theta rhythm EEG signal;

[0084] S32, calculating and processing the preprocessed EEG signal and the θ rhythm EEG signal to obtain the EEG characteristic value.

[0085] S4. Process the θ rhythm EEG signal and the EEG characteristic value to obtain ultrasound stimulation parameters and θ rhythm stimulation phase setting.

[0086] like Figure 4 As shown, this step specifically includes:

[0087] S41, calculating the error between the EEG characteristic value and the preset expected value, and obtaining the ultrasound control parameter according to the control strategy;

[0088] S42, calculating the theta rhythm phase of the theta rhythm electroencephalogram signal by using the Hilbolt transform;

[0089] S43, setting a stimulation phase of the theta rhythm of the theta rhythm electroencephalogram signal predicted by a theta rhythm phase and a prediction model.

[0090] S5. Setting a stimulation phase according to the ultrasonic stimulation parameters and the theta rhythm, and issuing ultrasonic stimulation to the experimental subject to perform EEG regulation.

[0091] like Figure 5 As shown, this step specifically includes:

[0092] S51, generating a first control waveform signal according to the ultrasound stimulation parameters and the θ rhythm setting stimulation phase;

[0093] S52, amplifying and processing the first control waveform signal to obtain a second control waveform signal;

[0094] S53, enabling the second control waveform signal to be output as an ultrasonic signal;

[0095] S54, limiting the ultrasonic signal within a set spatial range and transmitting it to the experimental object.

[0096] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A closed-loop EEG control method, characterized in that: The method comprises the following steps: Receive EEG signals from the subject; Preprocessing the EEG signal to obtain a preprocessed EEG signal; Calculating and processing the preprocessed EEG signal to obtain a theta rhythm EEG signal and an EEG characteristic value; Processing the theta rhythm electroencephalogram signal and the electroencephalogram characteristic value to obtain ultrasonic stimulation parameters and theta rhythm stimulation phase setting; Setting a stimulation phase according to the ultrasonic stimulation parameters and the theta rhythm, and issuing ultrasonic stimulation to the experimental subject to perform EEG regulation; The step of calculating and processing the preprocessed EEG signal to obtain the θ rhythm EEG signal and the EEG characteristic value specifically includes the following steps: Performing 4-8 Hz filtering on the preprocessed EEG signal to obtain a theta rhythm EEG signal; The preprocessed EEG signal and the θ rhythm EEG signal are calculated and processed to obtain the EEG characteristic value; the EEG characteristic value includes the absolute power of the preprocessed EEG signal, the relative power of the θ rhythm EEG signal with respect to the preprocessed EEG signal, and the sample entropy.

2. The closed-loop EEG control method according to claim 1, characterized in that: Preprocessing the EEG signal to obtain a preprocessed EEG signal specifically comprises the following steps: The EEG signal is downsampled, subjected to 50 Hz notch denoising and 4-200 Hz filtering to obtain a preprocessed EEG signal.

3. The closed-loop EEG control method according to claim 1, characterized in that: The θ rhythm EEG signal and the EEG characteristic value are processed to obtain ultrasound stimulation parameters and the θ rhythm stimulation phase setting, specifically comprising the following steps: Calculating the error between the EEG characteristic value and the preset expected value, and obtaining the ultrasound control parameter according to the control strategy; Calculating the theta rhythm phase of the theta rhythm electroencephalogram signal by using Hilbol transform; The stimulation phase is set according to the theta rhythm phase and the theta rhythm of the theta rhythm electroencephalogram signal predicted by the prediction model.

4. The closed-loop EEG control method according to claim 3, characterized in that: The control strategy is a generalized minimum variance control strategy.

5. The closed-loop EEG control method according to claim 1, characterized in that: According to the ultrasonic stimulation parameters and the θ rhythm, the stimulation phase is set, and ultrasonic stimulation is given to the experimental subject to perform EEG regulation, which specifically includes the following steps: Generate a first control waveform signal according to the ultrasound stimulation parameter and the theta rhythm setting stimulation phase; amplifying and processing the first control waveform signal to obtain a second control waveform signal; enabling the second control waveform signal to be output as an ultrasonic signal; The ultrasonic signal is confined within a set spatial range and emitted to the experimental object.

6. A closed-loop EEG control system according to any one of claims 1 to 5, characterized in that: include: A processing module, configured to receive and pre-process the EEG signal of the experimental subject to obtain a pre-processed EEG signal, and further configured to calculate and process the pre-processed EEG signal to obtain a theta rhythm EEG signal and an EEG characteristic value; A control module configured to process the theta rhythm EEG signal and the EEG characteristic value to obtain ultrasound stimulation parameters and theta rhythm stimulation phase setting; The ultrasonic stimulation module is configured to set the stimulation phase according to the ultrasonic stimulation parameters and the theta rhythm, and to emit ultrasonic stimulation to the experimental subject to perform brain electrical regulation.

7. The closed-loop EEG control system according to claim 6, characterized in that: The processing module comprises: A preprocessing module is configured to receive the EEG signal, and perform downsampling, notch denoising and filtering on the EEG signal to obtain a preprocessed EEG signal; a theta rhythm electroencephalogram calculation module, configured to perform 4-8 Hz filtering on the preprocessed electroencephalogram signal to obtain a theta rhythm electroencephalogram signal; The EEG characteristic value calculation module is configured to calculate and process the preprocessed EEG signal and the θ rhythm EEG signal to obtain the EEG characteristic value.

8. The closed-loop EEG control system according to claim 6, characterized in that: The control module comprises: a theta rhythm phase prediction module, configured to calculate the theta rhythm phase of the theta rhythm electroencephalogram signal by using a Hilbolt transform, and further configured to predict the theta rhythm setting stimulation phase of the theta rhythm electroencephalogram signal according to the theta rhythm phase and a prediction model; The ultrasonic control parameter calculation module is configured to calculate the error between the EEG characteristic value and a preset expected value, and obtain the ultrasonic control parameter according to the control strategy.

9. The closed-loop EEG control system according to claim 6, characterized in that: The ultrasonic stimulation module comprises: A signal generating module configured to generate a first control waveform signal according to the ultrasonic stimulation parameter and the theta rhythm setting stimulation phase; a power amplification module, configured to amplify and process the first control waveform signal to obtain a second control waveform signal; An ultrasonic transducer module, configured to enable the second control waveform signal to be output as an ultrasonic signal; The collimation module is configured to limit the ultrasonic signal within a set spatial range and transmit it to the experimental object.

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