A transcranial direct current stimulation memory enhancement method based on a brain-computer interface

Abstract

The present invention provides a transcranial direct current stimulation memory enhancement method based on a brain-computer interface. It includes an electrical stimulation stage based on a brain-computer interface and a memory consolidation stage based on image discrimination. In the electrical stimulation stage based on a brain-computer interface, transcranial direct current stimulation is used in combination with a brain-computer interface to apply electrical stimulation to fixed scalp points in turns. In the memory consolidation stage based on image discrimination, the memory enhancement effect is tested by learning, recalling, and judging image information. Advantageous effects of the present invention: The present invention has strong technical feasibility. By means of a new memory experiment, it improves the problems of large memory volume and susceptibility to subjective state influence in existing memory experiments. Combining brain-computer interface technology, it improves the feature that existing research cannot deeply explore memory enhancement from the structural level. The memory experiment plays a role in memory consolidation to a certain extent and can provide data support for whether the memory ability is enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical engineering brain-computer interface, and specifically relates to transcranial direct current stimulation technology. It is a transcranial direct current stimulation memory enhancement method based on the brain-computer interface. Background Art

[0002] Memory is the memorization, retention, and reproduction of things experienced by the brain, and it is the basis for higher mental activities such as thinking and imagination. The limited capacity of memory also reflects the bottleneck of human cognitive system processing and handling to a certain extent. The research on memory has always been a key direction in the scientific field. Scientists such as Kaplan found that when the relevant information of cognitive activities is transmitted between brain regions, the neuronal synchrony of electroencephalogram (EEG) signals in each frequency band will be weakened in the task-related cortical regions and enhanced in the task-unrelated cortical regions. This proves that the synchrony of EEG signals is related to the memory ability of the brain.

[0003] Transcranial direct current stimulation (tDCS) is an emerging neuromodulation technology. It is a technology that uses a constant, low-intensity direct current to stimulate specific points on the scalp to regulate the activities of cortical neurons. This technology is a non-invasive treatment or rehabilitation technology with high safety.

[0004] In recent years, research has shown that transcranial direct current stimulation is an important intervention method for improving short-term memory. The synchronous electrophysiological rhythm in the human body is the core mechanism for shaping the signal communication between brain networks, and there is a strong correlation between brain networks and cognitive abilities in neuropsychiatric disorders. By means of external direct current stimulation technology, the cortical layer related to short-term memory in the brain can be activated in the short term, thereby enhancing a person's short-term memory.

[0005] Brain-computer interface technology is the key technology for collecting and processing EEG signals. At present, the research in the field of brain-computer interface mainly focuses on the one-way brain-computer interface from brain to machine. The two-way brain-computer interface technology is based on the one-way brain-computer interface and adds devices for interacting with the external environment to transmit the information generated by them to the brain, thereby realizing the interaction channels of "from brain to machine" and "from machine to brain". In recent years, the development of neuromodulation technology has made it possible for "from machine to brain". Regulating neural activities will be an important part of the two-way brain-computer interface. The development of the two-way brain-computer interface technology provides a new solution for the treatment of brain diseases such as stroke and epilepsy, and has an innovative effect on the study of the human brain neural network.

[0006] Based on the use of a new memory consolidation experiment, the present invention proposes a method for enhancing memory by transcranial direct current stimulation based on a brain-computer interface. Utilizing two-way brain-computer interface technology to achieve brain-computer interaction in the electrostimulation-EEG acquisition mode is conducive to studying the synchronization between the memory improvement effect and EEG signals, and improving the drawback of high uncertainty in existing memory enhancement research. Summary of the Invention

[0007] To address the problems of large memory volume, significant influence of subjective state, and inability to analyze the performance of memory enhancement from the perspective of EEG signals in memory experiments. The present invention aims to provide a new method for detecting memory enhancement based on a brain-computer interface.

[0008] To achieve the above-mentioned invention objective, the technical solution of the present invention is a memory test experiment based on image position change classification and a two-way brain-computer interface in the electrostimulation-EEG acquisition mode.

[0009] Select the transcranial direct current stimulation mode, apply a direct current with a constant intensity to specific points in the frontal lobe area and parietal lobe area of the brain, control the stimulation time to 1100 seconds, and adjust the placement areas of the anode and cathode of the electrostimulation based on the feedback of memory experiment data after electrostimulation.

[0010] In the memory experiment based on image recognition, it is necessary to determine whether the positions of the objects in two consecutive pictures are of the same category. The pictures are divided into 4 category areas. When the objects in two pictures that appear at intervals are in the same category area, the user needs to press a key for classification. Through this memory experiment based on image recognition, it reduces the problems of large memory volume and susceptibility to subjective state in traditional memory experiments such as the array memory efficiency test method, the word efficiency test method without logical connection, and the short-term recall test method, and can intuitively and scientifically quantify the effect of memory enhancement through the final correct rate, providing data feedback for the electrostimulation stage and data support for accurately finding the brain area points that effectively enhance memory.

[0011] During the experiment, EEG signals are collected. The EEG signals of the entire process are collected during the experiment and marked at the 3rd second after the start of the experiment. After the experiment, in combination with the results of the memory test experiment, the changes in EEG signals within 3 seconds after the start of the experiment are analyzed. Brief Description of the Drawings

[0012] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0013] Figure 1 It is the basic system diagram of the method for enhancing memory by transcranial direct current stimulation based on a brain-computer interface according to the embodiment of the present invention;

[0014] Figure 2 This is a diagram of the memory experiment paradigm in the memory consolidation stage based on image recognition according to the embodiments of the present invention;

[0015] Figure 3 This is a flowchart of the transcranial direct current stimulation memory enhancement method based on a brain-computer interface according to the embodiments of the present invention. Detailed implementation manners

[0016] The experiment is based on a brain-computer interface system, which mainly includes a transcranial direct current stimulator, a 32-channel electrode cap, an electroencephalogram (EEG) acquisition instrument, a signal amplifier, a computer, and a user. This experiment is carried out in a quiet laboratory with good sound insulation. The user sits on a comfortable chair, 60 cm away from the computer screen. The user is in good mental state, and the experimental impedance is required to be below 5 KΩ.

[0017] The present invention is mainly divided into two stages: the electrical stimulation stage based on a brain-computer interface and the memory consolidation stage based on image recognition.

[0018] Electrical stimulation stage based on a brain-computer interface: Select the F3, F5, and F1 EEG channels in the 64-channel EEG lead diagram as the anode patch placement positions, apply a current of 50 μA respectively, and select the Fz EEG channel as the cathode patch placement position to conduct an electrical stimulation experiment on the user for 1100 seconds. After the experiment, rest for 1 minute and conduct the next memory experiment, while collecting EEG signals. After the experiment, count the user's correct rate. Then rest for 6 to 10 minutes according to the user's situation.

[0019] While the user is conducting the memory experiment, use brain-computer interface technology to collect the user's EEG signals, collect the EEG signals throughout the process after the experiment starts, and mark the EEG signal data in the first 3 seconds.

[0020] Memory consolidation stage based on image recognition: At the beginning of the experiment, the user conducts a memory experiment and collects EEG. After the experiment, count the user's correct rate. The content of the memory experiment includes: The user will first see an operation prompt diagram, and the operation prompt will be displayed for 3 seconds, and the user needs to get ready during this period. In the formal experiment, the user needs to judge whether the positions of the balls in two pictures presented at intervals are of the same type within 3 seconds. Each time during the judgment process, the ball will randomly appear at any position in a 4x4 sixteen-grid. When the ball appears in the same 2x2 four-grid at the four corners of the sixteen-grid, it is of the same type. When the user judges that the positions of the balls are of the same type, press the "Y" key on the keyboard to confirm, otherwise press "F". Each memory experiment includes 15 groups of training diagrams, each group includes 16 training pictures, and a prompt picture showing a white cross will appear before each training picture to remind the user of the upcoming training picture for 1 second. Each training picture is displayed for 3 seconds.

[0021] After each training session, the training results will be displayed, including the number of times the same category appeared in the experiment, the number of times the user classified correctly, and the number of times the user classified incorrectly. The display time is two seconds. The user can take a break during these 2 seconds and then start the next set of tests.

[0022] After the user goes through the electrical stimulation stage, the next memory experiment is conducted while collecting electroencephalogram (EEG) signals and marking the EEG signal data for the first 3 seconds.

[0023] After the experiment, the correct rate of pressing the "Y" key and the correct rate of pressing the "F" key during the user's experiment are statistically analyzed, and the weighted correct rate is calculated. The weighted correct rates of the user in the two experiments are compared. Based on the improvement of the weighted correct rates in the two experiments, it is judged whether the electrical stimulation effect is obvious. When the effect is not obvious, the stimulation points are appropriately adjusted and the experimental process is restarted.

[0024] Combining the EEG signals collected in the two experiments, calculate the average energy density values of the theta frequency band in 14 channels of the EEG signals collected in the two times, and evaluate the memory enhancement effect from the EEG level. When the increase in the energy density value of the EEG signal collected in the second time exceeds 300 μV 2 / Hz, the memory enhancement effect is evaluated in combination with the results of the memory experiment and the user's own feelings.

Claims

1. A transcranial direct current stimulation memory enhancement method based on a brain-computer interface, characterized in that The two-way brain-machine interface technology composed of neuromodulation technology is used to achieve a two-way channel of "from brain to machine" and "from machine to brain". On the basis of enhancing memory by electrical stimulation, the electroencephalogram (EEG) signals of the human brain are obtained, and the memory enhancement effect is explored from the signal level; a memory consolidation stage is added, and the memory enhancement effect data is quantified from the perspective of behavioral science, more intuitively showing the degree of memory enhancement, and providing a data basis for the correction of the stimulation point. The transcranial direct current stimulation (tDCS) memory enhancement method based on a brain-machine interface is composed of two stages: the electrical stimulation stage based on a brain-machine interface and the memory consolidation stage based on image discrimination. It is characterized in that: the electrical stimulation stage based on a brain-machine interface realizes a double-pass loop through the two-way brain-machine interface technology, stimulates the brain area points related to memory, enhances memory, and observes the memory enhancement effect from the EEG signal level; the memory consolidation stage based on image discrimination consolidates and detects the improvement level of memory; it includes the following steps: Step S1: Select the transcranial direct current stimulation mode for electrical stimulation. Step S2: Conduct a memory experiment to test the user's judgment accuracy rate and consolidate the user's memory ability. Step S3: Collect EEG signals during the memory experiment. The transcranial direct current stimulation memory enhancement method based on a brain-machine interface is characterized in that: in the memory consolidation stage based on image discrimination, the user needs to judge and classify the positions of objects. The classification principle is to evenly divide a 16-grid into four 4-grid sub-grids, and the positions of the four small grids contained in each 4-grid sub-grid are regarded as one category. When the objects in two pictures shown at intervals are in the same category of positions, the user presses a key for classification; the specific process of judging and classifying pictures is as follows: during each judgment process, the ball will randomly appear at any position in a 4x4 16-grid. When the ball appears in the same 2x2 4-grid at the four corners of the 16-grid, it is regarded as one category; each picture is displayed for 3 seconds, and the user needs to judge whether two non-consecutive pictures are of the same category. If the two pictures are of the same category, the user needs to press the Y key for classification processing. If they are not of the same category, the user needs to press the F key; finally, the memory enhancement effect of the user is analyzed by statistically calculating the accuracy rate of the user pressing the Y key and the accuracy rate of pressing the F key.

2. The transcranial direct current stimulation memory enhancement method based on a brain-computer interface according to claim 1, characterized in that: In the electrical stimulation stage based on a brain-machine interface, after the transcranial direct current stimulation ends, during the memory experiment stage, the brain-machine interface is used to collect EEG signals to form a two-way brain-machine channel, and the collected EEG signals and memory experiment data are used to provide feedback to the user.

3. The transcranial direct current stimulation memory enhancement method based on a brain-computer interface according to claim 1, wherein: In the electrostimulation phase based on the brain-computer interface, the stimulation points are selected as the anode patch placement points at the F3, F5, and F1 channels in the frontal lobe, and the Fz channel is the cathode patch placement point; the stimulation time is 1100 seconds, and the anode stimulation current density is 0.0589 mA / cm 2 ; After the start of the memory detection phase, electroencephalogram (EEG) is collected using the brain-computer interface. The brain regions for collection are the frontal lobe and parietal lobe, and the collection channels are the FP1, FP2, AF3, AF4, F3, F4, F7, F8, FZ, FC1, FC2, FC5, FC6, and CZ channels in the 64-channel EEG lead map; the EEG signals 3 seconds before the memory experiment are collected.

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