CN110811613B

CN110811613B - Method for improving event-related potential signal-to-noise ratio based on European Debao and DMST paradigm fusion

Info

Publication number: CN110811613B
Application number: CN201911156299.9A
Authority: CN
Inventors: 李梦凡; 杨光; 李红超; 宫铭鸿
Original assignee: Hebei University of Technology
Current assignee: Hebei University of Technology
Priority date: 2019-11-22
Filing date: 2019-11-22
Publication date: 2022-09-27
Anticipated expiration: 2039-11-22
Also published as: CN110811613A

Abstract

The invention relates to a method for improving an event-related potential signal-to-noise ratio based on the fusion of an Oudebao paradigm and a DMST paradigm, belongs to the technical field of biomedical engineering brain-computer interfaces, and aims to provide a method for improving the event-related potential signal-to-noise ratio and deeply exploring a brain visual cognition process. The technical scheme is based on electrode cap, brain electricity collection appearance, signal amplifier, arouses event correlation potential through the visual stimulation method, and brain electricity collection appearance is gathered and is conveyed signal amplifier through the electrode cap, and signal amplifier transmits the computer, its characterized in that after enlargiing the brain electricity signal: the visual stimulation method based on the fusion of the European DeBao and the DMST model comprises three stages of training, delaying and testing, wherein the training stage is completed by the European DeBao single flash mode, the delaying stage is formed by the delaying stage in the DMST, and the testing stage is formed by the matching stage in the DMST.

Description

Method for improving event-related potential signal-to-noise ratio based on European Debao and DMST paradigm fusion

Technical Field

The invention belongs to the technical field of biomedical engineering brain-computer interfaces, and particularly relates to a method for inducing event-related potentials.

Background

Visual stimuli play an important role in brain-computer interface systems based on event-related potentials. The robot is a common controlled object in a brain-computer interface system, and the visual stimulation based on the robot graph has the problems of low evoked potential signal-to-noise ratio and shallow exploration of the brain on the visual stimulation cognitive process in the evoked event related potential process.

At present, the relevant potential of the event can be induced through the European Deguage mode, but the brain cognitive visual stimulation process cannot be deeply explored; brain cognitive exploration can be performed through an N-back experiment, but the induced event-related potential signal-to-noise ratio is low.

How the brain better understands the graphic visual stimulation of the robot and induces event-related potentials with higher signal-to-noise ratio is an urgent problem to be solved. The invention provides an experimental method for inducing and brain memory fusion.

Disclosure of Invention

Aiming at the existing experimental defects, the invention aims to provide a method for improving the signal-to-noise ratio of event-related potential and deeply exploring the brain visual cognition process. The technical scheme for realizing the aim of the invention is the fusion of the Oudersu task and the sample delay matching task (DMST).

The experiment is based on a brain-computer interface system and mainly comprises 64 conducting electrode caps, an electroencephalogram acquisition instrument, a signal amplifier, a computer and a tested object. The 64 conductive electrode cap is worn on the head of the testee and connected with an electroencephalogram acquisition instrument for transmitting the electroencephalogram signals of the testee. One end of the electroencephalogram acquisition instrument is used for acquiring electroencephalogram signals of the 64 conductive electrode caps, and the other end of the electroencephalogram acquisition instrument is connected with the signal amplifier and is used for acquiring the electroencephalogram signals to be tested. One end of the signal amplifier is connected with the electroencephalogram acquisition instrument, and the other end of the signal amplifier is connected with the computer and is used for amplifying the electroencephalogram signals and transmitting the signals to the computer. On one hand, the computer receives the signal transmitted back by the amplifier, and on the other hand, the computer induces the tested brain electrical signal as a tool of visual stimulation. The oudebao and DMST fusion provided visual stimuli to the subjects via computer.

The European Debao and DMST fusion comprises three stages of training, delaying and testing: the training phase is completed by a single flash in the oude protective form, the delay phase is composed of the delay phase in the DMST, and the testing phase is completed by the matching phase of the DMST. In the oudebao uniflash training phase, stimuli of evoked event-related potentials are often haphazard and unpredictable, and therefore appear evoked as two visual stimuli, where stimuli that occur at a large probability are referred to as standard stimuli and stimuli that occur at a small probability are referred to as bias stimuli. The interface of evoked event-related potentials was designed using standard and deviation stimuli during the oudebao monarch training phase, while this phase served as the sample phase of the DMST for visual stimulation of the subject. The stimuli of the ondansu single flash training phase fall into two categories: the biased stimulus is compared to the standard stimulus, which advantageously improves the signal-to-noise ratio of the event-related potential. The interval of seconds after the stimulus of the sample stage disappears is a delay stage, and the visual stimulus of the picture appearing in the final matching stage requires to be tested to judge whether the stimulus is matched with a certain stimulus of the sample stage. The matching phase of the DMST serves as the testing phase. The purpose of the testing stage is to guide the corresponding behaviors of the tested matched visual stimuli and the memory, so that the memory matching link is highlighted, and help is provided for researching the cognitive visual stimuli process of the brain.

Advantageous effects

The invention has the advantages that the signal-to-noise ratio of event-related potential is increased through the designed Oudebao and DMST fusion robot visual stimulation experiment, and strong evidence is provided for exploring the brain cognitive visual stimulation process through the event-related potential induced by the memory matching task.

Drawings

FIG. 1 is an Oudenbo flash training interface.

FIG. 2 is a single deal timing diagram.

FIG. 3 is a flow chart of the experiment.

Detailed Description

The experiment is carried out in a quiet laboratory with good sound insulation effect. The test was seated in a comfortable chair 70cm from the computer screen. The tested mental state is good, the hair is neat, and the experimental impedance is required to be below 5K omega. Before the experiment begins, the head of the tested person wears 64 conductive electrode caps to explain the experiment process to the tested person until the tested person completely understands the experiment flow and then begins the experiment.

The training phase is completed by a single flash in the Oudebao paradigm and is realized by Openvibe software. The interface displays a 3-row and 4-column virtual picture matrix (as shown in fig. 1) on a computer screen, the stimulation is generated by randomly flashing a certain picture, and the flashing times of each picture are the same. The duration of the picture stimulation is 150ms, and the time interval between two adjacent flickers is 75 ms. The experimental period (repetition) is defined herein to mean the process in which all pictures complete one flash, and the experimental unit (trial) is a process consisting of 10 experimental periods. A total of 12 experimental units were used for one set of experiments. Within a trial, the subject is asked to focus on the gaze and memorize the target picture. The experiment is started, firstly, the first experiment period in the first experiment unit is started, all pictures are required to flash once in one experiment period, the picture in the first row and the first column (namely, the first picture) is set as a target picture, a target picture is required to be tested and looked at, the stimulation generated by the target picture is deviation stimulation, the stimulation generated by the target picture is required to be tested and counted in the heart, and the stimulation generated by other 11 pictures is standard stimulation, and the test counting is not required. Repeat 10 times, complete 10 experimental cycles in the first experimental unit. The first experiment cycle of the second experiment unit is followed, and at this time, the first row and the second column of pictures (the second picture) are set as the target pictures, and the second experiment unit is completed without changing other methods. And sequentially setting a third picture as a target picture, completing a third experiment unit until the last picture is taken as the target picture to complete a 12 th experiment unit, and thus completing the Oudenbu training stage. In this experimental paradigm, the probability of the occurrence of the deviation stimulus is 1/12 and the probability of the occurrence of the standard stimulus is 11/12.

The testing phase is completed by the DMST matching phase and is realized by E-prime software. The training phase is provided by the OudeBao single flash; the delay stage time is 4000 ms; in the matching stage, the tested person is required to sequentially judge whether 20 pictures appear in the Oudenbul single flash, the judging time of each picture is 1500ms, if the pictures appear, the tested person can react by pressing a keyboard 'j', and if the pictures do not appear, the key 'f' is pressed. If the tested picture is judged within 1500ms, processing the picture according to judgment error, wherein a 1000ms time interval exists between every two pictures, and a '+' symbol appears in the center of the screen during the interval. Of the 20 pictures in each experimental matching stage, 5 pictures appeared in the oude protective training stage, and 15 pictures did not appear.

The relevant potential of the event is induced by the fusion of the visual stimulation of the Oudebao and the DMST, the electroencephalogram acquisition instrument acquires and transmits the acquired potential to the signal amplifier, and the signal amplifier amplifies the electroencephalogram signal and transmits the amplified signal to the computer.

Claims

1. A method for improving the signal-to-noise ratio of event-related potentials based on the fusion of Oudebao and DMST paradigm is characterized in that event-related potentials are induced by a visual stimulation method based on an electrode cap, an electroencephalogram acquisition instrument and a signal amplifier, the electroencephalogram acquisition instrument acquires and transmits the events to the signal amplifier through the electrode cap, and the signal amplifier amplifies the electroencephalogram signals and then transmits the signals to a computer, wherein the method comprises the following steps: the visual stimulation method based on the DMST model fusion of the Oudebao and the sample delay matching task comprises three stages of training, delaying and testing, wherein the training stage is completed by an Oudebao single flash mode, the delaying stage is formed by a delaying stage in DMST, and the testing stage is formed by a matching stage in DMST; the training stage specifically comprises: all pictures are displayed on a screen in a matrix form, one picture is designated as a target picture during each experiment, when the target picture flickers to generate deviation stimulation, the related potential of an evoked event requires to be counted, and when a non-target picture flickers to generate standard stimulation, the to-be-counted is not required; the picture stimulation duration time in the training stage is 100-200ms, the time interval of two adjacent flickers is 50-100 ms, and the picture is a humanoid robot;

the pictures used in the matching stage comprise partial pictures appearing in the training stage;

the concrete process of the matching stage is as follows: and requiring the tested to sequentially judge whether each picture appears in the European DeBao single flash type training stage, wherein the time length of whether one picture appears in the European DeBao single flash type training stage is not more than 1500 ms.