阅读说明：本技术 一种面向双眼竞争的视觉稳态诱发电位检测系统 (Visual steady-state evoked potential detection system oriented to binocular competition ) 是由 董宇涵 单晴岚 李志德 张凯 于 2021-08-30 设计创作，主要内容包括：本发明公开了一种面向双眼竞争的视觉稳态诱发电位检测系统,包括刺激系统与采集与分析系统,所述刺激系统包括虚拟现实头戴式显示器,采集与分析系统包括脑电提取装置、脑电信号放大器、脑电信号采集器、脑电信息号分析模块和结果输出装置；所述显示屏用于显示图像以预定频率交替变化的闪烁块,对被试者施加视觉刺激；用脑电装置提取被试者接收视觉刺激之后的脑电信号,提取的脑电信号经脑电信号放大器放大后传输给脑电信号采集器,采集脑电信号后传输给脑电信号分析模块,经过分析处理后由结果输出装置输出。设备简单、操作方便,可以有效提高检测的精度,是一种很有应用潜力的方案。(The invention discloses a visual steady-state evoked potential detection system facing binocular competition, which comprises a stimulation system and an acquisition and analysis system, wherein the stimulation system comprises a virtual reality head-mounted display, and the acquisition and analysis system comprises an electroencephalogram extraction device, an electroencephalogram signal amplifier, an electroencephalogram signal acquisition device, an electroencephalogram information number analysis module and a result output device; the display screen is used for displaying the flash blocks with images changing alternately at a preset frequency and applying visual stimulation to a testee; the electroencephalogram signal after the visual stimulation is received by the testee is extracted by the electroencephalogram device, the extracted electroencephalogram signal is amplified by the electroencephalogram signal amplifier and then transmitted to the electroencephalogram signal collector, the electroencephalogram signal is collected and then transmitted to the electroencephalogram signal analysis module, and the electroencephalogram signal is analyzed and processed and then output by the result output device. The device is simple, the operation is convenient, the detection precision can be effectively improved, and the method is a scheme with application potential.)

1. A visual steady-state evoked potential detection system facing binocular competition is characterized by comprising a system stimulation system and a collection and analysis system, wherein the stimulation system comprises a virtual reality head-mounted display, and the collection and analysis system comprises an electroencephalogram extraction device, an electroencephalogram signal amplifier, an electroencephalogram signal collector, an electroencephalogram information number analysis module and a result output device; the display screen is used for displaying the flash blocks with images changing alternately at a preset frequency and applying visual stimulation to a testee; the electroencephalogram signal after the visual stimulation is received by the testee is extracted by the electroencephalogram device, the extracted electroencephalogram signal is amplified by the electroencephalogram signal amplifier and then transmitted to the electroencephalogram signal collector, the electroencephalogram signal is collected and then transmitted to the electroencephalogram signal analysis module, and the electroencephalogram signal is analyzed and processed and then output by the result output device.

2. The binocular rivalry oriented visual steady-state evoked potential monitoring system of claim 1, wherein: the virtual reality head-mounted display is internally provided with an independently operable device or is operated and displayed based on a PC computer.

3. The binocular rivalry oriented visual steady-state evoked potential monitoring system of claim 1, wherein: the predetermined frequency is set according to the different devices and the optimal stimulation frequency to be tested.

4. The binocular rivalry oriented visual steady-state evoked potential monitoring system of claim 1, wherein: the virtual reality head mounted display has dual independent rendering display screens.

5. The binocular rivalry oriented visual steady-state evoked potential monitoring system of claim 4, wherein: the applying of the visual stimulus to the subject includes encoding in a predetermined form with different stimulus frequencies for the left and right eyes.

6. The binocular rivalry oriented visual steady-state evoked potential monitoring system of claim 5, wherein: the predetermined form code is: high and low frequencies alternate.

7. The binocular rivalry oriented visual steady-state evoked potential monitoring system of claim 1, wherein: the stimulation system includes 3D and 2D stimulation sources developed using three-dimensional modeling software to differentiate and distribute simultaneous stimulation.

8. The binocular rivalry oriented visual steady-state evoked potential monitoring system of claim 7, wherein: the frequency of the stimulation includes 7.5Hz, 6 Hz.

9. The binocular rivalry oriented visual steady-state evoked potential monitoring system of claim 8, wherein: the device also comprises a detection device, and stereoscopic vision detection is carried out through a 3D and 2D contrast experiment.

Technical Field

The invention relates to the field of visual steady-state evoked potential, and provides a visual steady-state evoked potential detection method for binocular competitive detection.

Background

Binocular competition is a phenomenon that a single, stable perceptual dynamic alternation cannot be formed due to the disparity of images presented by both eyes. The binocular competition has important significance in the detection ranges of clinic, medicine, psychology and the like.

The current research methods and measurement indexes for binocular competition include: duration, rate of alternation, etc. The current measuring and using mode for binocular competition is to display stimulation pictures with different difficulty degrees and different information in a screen, enable two eyes to feel the stimulation forms of different pictures through polarized glasses, and meanwhile assist a tester to feed back currently presented dominant perceptual information through a behavioral key design. At present, an experimental system for Binocular competitive research uses an active shutter camera and a polarization display to perform detection [ Gu L, Deng S, Feng L, et al. effects of monomeric peripheral Learning on Binocular Visual Processing in additive and amplified Visual information [ J ]. iSience, 2020,23(2):100875], which has limitations on the operation of equipment, the unicity of left and right eye optical paths, the number of frames and colors of picture selection, and the like, cannot meet the requirements for independently Processing Binocular fusion complex information, and cannot meet the requirements for three-layer Visual function detection such as simultaneous vision, fusion vision, and the like. Meanwhile, due to the defects of light leakage, frequency interference and the like of the polarization display equipment, the acquisition of wrong data during binocular competitive detection is easily caused, and the experimental result is influenced.

The visual steady evoked potential is a potential of cerebral cortex, usually after the evoked potential has an electroencephalogram signal in the occipital lobe area of the cerebral cortex, and the evoked stimulus is a stimulus form of moving with constant and stable frequency. Changes in visual evoked potentials are thought to coincide with the perceptual state being tested, and the amplitude of the brain waves increases when a stimulus is in a perceptual state, and decreases when it is suppressed [ Brown R J, Northa M J V R.A method for inducing a binding restriction in real-time with the steady-state VEP [ J ].1997,37(17):2401-8 ]. Steady State Visual Evoked Potential (SSVEP) is a Potential related to Visual sensory stimuli, and when a subject receives a Visual stimulus of a fixed frequency or a fixed combination of frequencies, a continuous, corresponding electrical signal related to the stimulus frequency is recorded in the relevant area of the Visual cortex of the human brain. It has the common feature of evoked potentials, typically occurring in the occipital region, occipital lobe, etc., in a waveform distribution similar to a sine wave, with a relatively strict time-lock relationship with latency between visual stimuli, and SSVEP is usually related in frequency to the fundamental or the multiple frequency of the stimulus flicker [ Brown R J, Northa A M J V R.A method for exciting a binding temporal in real-time with the steady-state VEP [ J ].1997,37(17):2401-8 ]. Through the cross stimulation of the visual steady-state evoked potential stimulus source, binocular competitive phenomenon signals can be separated, and the binocular competitive degree can be indirectly judged from the strength and duration of the cerebral cortex visual steady-state evoked potential signals. Visual steady-state evoked potentials are widely present in the general population and are commonly used to objectively mark objects being identified or perceived.

The visual steady-state evoked potential generated by the brain primary cortex reaction can be used for detecting the primary visual cortex reaction by the corresponding resonance frequency difference in the brain cortex caused by the different display frequency of the stimulation picture, and the perception state of binocular competition can be perceived without a behavior experiment mode. Compared with the traditional method for detecting binocular competition, which combines an experimental target with a behavioral detection controller, the method has the defects of subjective judgment and response delay, the visual Steady-State Evoked Potential is a physiological electric signal which can be Evoked without human body response, and the activation State of the cerebral cortex under the current binocular competition can be objectively displayed [ Yang D, Nguyen T H, Chung W Y.A Bipolar-Channel Hybrid Brain-Computer Interface System for Home Automation Control oral diagnosis assisted Brain-State visual occupied patent and Eye-Blink Signals [ J ]. Sensors (base), 2020,20(19) ].

Amblyopia is one of common eye diseases of children, and many amblyopic children are in the period of infants, because the visual development is influenced by the failure of receiving proper visual stimulation due to various reasons such as perception, movement, conduction, visual center and the like, the amblyopia state is generated, and the amblyopia state is mainly represented by low vision and binocular single vision dysfunction. Amblyopia eye vision cortex primary treatment of amblyopia patients is inhibited, and measurement of stereoscopic vision mainly needs treatment of advanced vision cortex, needs to be distinguished independently when detecting, needs to be trained and detected separately for achieving rehabilitation effect, and thus equipment is complex and inconvenient to operate.

Disclosure of Invention

In order to make up for the defects of the prior art, the invention provides a visual steady-state evoked potential detection system for binocular competition, which is simple in equipment and convenient to operate.

The technical problem of the invention is solved by the following technical scheme:

a visual steady-state evoked potential detection system facing binocular competition comprises a system stimulation system and a collection and analysis system, wherein the stimulation system comprises a virtual reality head-mounted display, and the collection and analysis system comprises an electroencephalogram extraction device, an electroencephalogram signal amplifier, an electroencephalogram signal collector, an electroencephalogram information signal analysis module and a result output device; the display screen is used for displaying the flash blocks with images changing alternately at a preset frequency and applying visual stimulation to a testee; the electroencephalogram signal after the visual stimulation is received by the testee is extracted by the electroencephalogram device, the extracted electroencephalogram signal is amplified by the electroencephalogram signal amplifier and then transmitted to the electroencephalogram signal collector, the electroencephalogram signal is collected and then transmitted to the electroencephalogram signal analysis module, and the electroencephalogram signal is analyzed and processed and then output by the result output device.

In some embodiments, the following further technical features are also included:

the virtual reality head-mounted display is internally provided with an independently operable device or is operated and displayed based on a PC computer.

The predetermined frequency is set according to the different devices and the optimal stimulation frequency to be tested.

The virtual reality head mounted display has dual independent rendering display screens.

The applying of the visual stimulus to the subject includes encoding in a predetermined form with different stimulus frequencies for the left and right eyes.

The predetermined form code is: high and low frequencies alternate.

The stimulation system comprises a 3D stimulation source and a 2D stimulation source which are developed by using three-dimensional modeling software, and the stimulation frequency comprises 7.5Hz and 6 Hz.

The device also comprises a detection device, and stereoscopic vision detection is carried out through a 3D and 2D contrast experiment.

Compared with the prior art, the invention has the advantages that: the virtual reality technology is used, the work of building a complex optical path in a real scene is reduced, and the inconvenience in operation when equipment and instruments such as a traditional same-sight glass are used is also reduced. Utilize the closed light path environment of wear-type display, carry on the detection development system among the virtual reality system and make and separately play up the image and detect about the eye, three-dimensional scene among the make full use of virtual reality environment can further advance through 3D and 2D contrast experiment and detect the stereovision and detect, can improve the independence that two eyes detected, consequently is a more advanced detecting system, can effectively improve the precision that detects, is a scheme that has very much the application potentiality.

Drawings

FIG. 1 is a development system flow diagram of an embodiment of the invention.

Fig. 2 is a flow chart of a stimulation paradigm according to an embodiment of the present invention.

Fig. 3 is a diagram of the channels in the brain associated with the visual cortex in accordance with an embodiment of the present invention.

FIG. 4 is a graph of stimulation display frequency and cross-validation for an embodiment of the present invention.

FIG. 5 shows a 2D stimulus source and a 3D stimulus source in accordance with an embodiment of the present invention.

Detailed Description

The invention will be further described with reference to the accompanying drawings and preferred embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

Before describing the embodiments, terms related to the embodiments of the present invention will be described:

visual function: the visual function is divided into three stages: and simultaneously, performing vision, fused vision and stereoscopic vision. The picture seen by human eyes is two-dimensional information, the two eyes are effectively processed together, the nerve excitation is transmitted to the brain along a perception system, and the visual signals from the two eyes are analyzed in the high-level center of the brain to be synthesized into a complete three-dimensional perception impression.

Virtual Reality (VR): virtual reality is a generic term for a class of virtual scenes and devices based on 3D development. The virtual reality technology is a computer system capable of creating and experiencing a virtual world, and the computer system consists of a graphic display device, an integrated computing device, an audio output device, an action and positioning capturing and positioning input device and generates an immersive feeling for a user. Image display devices have evolved over the years, from a single generation of single-rendering graphics display screens to independently-rendering display devices, with significant progress. Attributes of visual display devices include viewing area and viewable area, spatial resolution, display screen shape, light propagation, refresh rate, and efficacy, among others. The design of the virtual reality display device is generally based on static clues, motion clues of eyeballs, motion parallax, binocular visual inconsistency, stereo imaging and the like, and the design is also developed from a terminal display, a ring screen display, a workbench display and the like into a head-mounted display on a terminal of the display device. Due to the recent development of head-mounted displays, independent, portable display devices have become the first choice for virtual reality development in recent years. Built-in refraction lens of wear-type virtual reality, the light that launches the display screen passes through the environment of the real light path of refraction simulation, builds its ordinary display screen of immersive and wants to show in the virtual reality system, still needs to pass through secondary development, adaptation in the display screen of virtual reality wear-type display. The virtual reality head-mounted display displays stimulation pictures of two eyes in a closed, immersive and independent type two-eye screen display mode, and can eliminate interference caused by light leakage and frequency leakage of a polarization display and the like while displaying rich pictures.

Typical correlation analysis (CCA): the method is a multivariate statistical method for reflecting the overall correlation between two groups of indexes by using the correlation between comprehensive variable pairs. The basic principle is as follows: in order to grasp the correlation between the two sets of indexes as a whole, two representative comprehensive variables are extracted from the two sets of variables respectively.

The embodiment of the invention aims to design a visual steady-state evoked potential detection system, and the effect of independent imaging, visual steady-state evoked potential stimulation and acquisition analysis is realized by applying a virtual reality system double-screen independent rendering technology. The system can independently control double-screen display, cannot enable one eye of a user to be influenced by the light path of the other eye, uses the head-mounted display to block possible ambient light, creates an immersive real environment, and is connected with the electroencephalogram acquisition equipment, the amplifier and the analysis computer through the program interfaces, so that data can be processed and analyzed through a pattern recognition algorithm and a machine learning algorithm in the subsequent process, and finally, judgment of visual function detection is carried out.

The following embodiments of the invention utilize a virtual reality display technology, can independently render a graphic channel, provide a binocular independent optical channel for exciting independent binocular visual steady-state evoked potentials, and simultaneously utilize the response of the visual evoked potentials to cerebral cortex visual processing, so that the binocular independent optical channel can be used for detecting binocular rehabilitation conditions of amblyopia children, in particular to binocular competition and stereoscopic vision evaluation in amblyopia function.

In the following embodiments of the invention, the display light path is restored by using a virtual reality technology, and the visual function of amblyopia is detected by using the contrast of the 3D stimulus source and the 2D stimulus source. The phenomena of light leakage, light pollution, frequency interference and the like caused by using the polarization display are avoided.

The embodiment of the invention utilizes a virtual reality display technology, can independently render a graph path, provides an independent optical path for exciting independent binocular vision steady-state evoked potential, and simultaneously utilizes the vision evoked potential as the response of cerebral cortex vision processing to detect the binocular rehabilitation condition of amblyopia children, in particular to the assessment of binocular competition and stereoscopic vision in the amblyopia function. Because amblyopia eye vision cortex primary treatment of the amblyopia patient is inhibited, the measurement of the stereoscopic vision mainly needs the treatment of the advanced vision cortex, and the amblyopia eye vision cortex primary treatment needs to be distinguished independently when the amblyopia eye vision cortex primary treatment is detected, and the amblyopia eye vision cortex primary treatment needs to be used for training and detecting the stereoscopic vision and the planar vision independently for achieving the rehabilitation effect.

The system comprises the following components: the virtual reality head-mounted display (built-in equipment capable of running independently or running and displaying based on a PC (personal computer)), the electroencephalogram extraction device, the electroencephalogram signal amplifier, the electroencephalogram signal collector, the electroencephalogram information number analysis module and the result output device; the display screen is used for displaying the flash blocks with images changing alternately at a certain frequency and applying visual stimulation to a testee; the electroencephalogram signal after the visual stimulation is received by the testee is extracted by the electroencephalogram device, the extracted electroencephalogram signal is amplified by the electroencephalogram signal amplifier and then transmitted to the electroencephalogram signal collector, the electroencephalogram signal is collected and then transmitted to the electroencephalogram signal analysis module, and the electroencephalogram signal is analyzed and processed and then output by the result output device. The technical scheme described in this embodiment realizes the objective detection of the amblyopia eye on the stereoscopic perception capability based on the display of the electroencephalogram evoked potential on the visual cortex, as shown in fig. 1.

The principle of visual steady-state evoked potential (SSVEP) is that under the induction of constant visual stimulus, periodic electroencephalogram signals are generated on cerebral cortex, the frequency of the periodic electroencephalogram signals can comprise half-frequency, double-frequency and fundamental frequency components of the stimulus frequency, the frequency spectrum components are mainly based on the fundamental frequency, and correspondingly, the periodic electroencephalogram signals are mainly distributed on occipital visual cortex, as shown in figure 3, which is a 10-20 international electrode standard system (network search).

When the stimulation is coded in a certain form, and the left eye and the right eye present different stimulation frequencies, the two eyes can generate amplitude expressions with different frequencies due to different stimulation sources, and after the stimulation with high frequency and low frequency is alternately tested, the eye rehabilitation effect of amblyopia can be detected and evaluated according to the corresponding strength of the amplitude of the visual steady-state evoked potential.

The system is built, as shown in a flow chart 1, the system consists of a stimulation system and an acquisition and analysis system, a 3D development engine such as Unity3D is used on a component of the stimulation system, a C # language is carried for writing, VR development plug-ins of different platforms are required to be introduced, for example, a bird watching equipment manufacturer has a PICOVR SDK, on the basis of a development platform, a program for amblyopia detection such as an attached drawing 2 is written by using the C # language, a head-mounted display is used for rendering and displaying, then an electroencephalogram cap and a related electroencephalogram extraction device are worn, and a test is started. The signals then enter the brain and are processed and analyzed by an acquisition and analysis system, for example using a typical correlation analysis (CCA), fourier transform, etc. When the performance index is evaluated, the response amplitude is used as an index for measuring the binocular parallax function, and because the binocular vision paths of amblyopia patients are different, electroencephalograms acquired by the passive eyes are weaker than those of the active eyes, and the stereoscopic vision needs high-grade cortex participation, the measurement of the amblyopia condition can be carried out from the fundamental reason of the brain vision. In the experimental design of the test, the 3D stimulus source and the 2D stimulus source which are developed by using three-dimensional modeling software are distinguished and distributed for simultaneous stimulation. The stimulation frequency can be selected from 7.5Hz and 6Hz, and the device is distinguished according to different devices and the tested optimal stimulation frequency, and the stimulation paradigm adopted by the invention is shown in figure 4 due to the device selection. According to because virtual reality glasses adopt the mirror surface refraction principle, can restore the light path in the display screen in the position of broadcasting in real scene, can build 3D and immerse the sense, distinguish with the 2D picture to detect the stereovision more accurately to the senior visual cortex of brain. The 3D stimulus source is distinguished from the 2D stimulus source as in fig. 5.

If the test frequency spectrum and the power spectral density are obviously different and are distinguished by characteristics, the visual function of the eye is judged to be weaker than that of the other eye, finally, a detection result is output by an output device, an electroencephalogram extraction device of the testee is removed, and the test is completed.

System parameter

The design of an experimental paradigm is carried out in Unity3D by using a Unity3D 2020.1.0f1c1 version to load a Pico VR Unity SDK plug-in, and a file which can be run through an APK is loaded in a virtual reality head-mounted display of a Pico Neo Eye2 model, the screen resolution is 3840 multiplied by 2160, the field angle is 101 degrees, the screen refresh rate is 75Hz, and the running processor is HPC 845, 128G internal storage space. The brain electricity collection equipment uses a Borui health wireless transmission 64 to guide the collection system, is connected with a device which is configured as Intel Core i7 and GPU6600 and carries a Nurele collection analysis system.

Useful benefits of the present embodiment

The virtual reality technology is used, the work of building a complex optical path in a real scene is reduced, and the inconvenience in operation when equipment and instruments such as a traditional same-sight glass are used is also reduced. Utilize the closed light path environment of wear-type display, carry on the detection development system among the virtual reality system and make and separately play up the image and detect about the eye, three-dimensional scene among the make full use of virtual reality environment can further carry out the stereovision through 3D and 2D contrast experiment and detect, can improve the independence that binocular detected, provides a more advanced detection mode.

Performance indexes are as follows:

the present invention uses a typical correlation analysis (CCA) for detecting and evaluating the effect, and a standard CCA may also be used to analyze the potential correlation between two multi-dimensional data sets. For detection of SSVEP, given two SSVEP signal variables X and Y, a weight vector W is sought using CCA_xAnd W_ySo that the corresponding linear projections have the maximum cross-correlation.

Besides the input multi-lead SSVEP signal, the input Y needs a sine signal with the stimulation frequency f to be fitted into a multi-dimensional signal as a reference signal, and the correlation of the multi-dimensional signal is analyzed. The reference signal Y expression is as follows:

Y_f＝(sin(2πft)，cos(2πft)，…，sin(2πNft)，cos(2πNft)) (1)

n denotes the nth harmonic signal.

In brain-computer interface systems, the CCA method is to study the correlation between X and Y, examine the linear combination between the two overall characteristics, and find the weight W_xAnd W_ySo that the correlation values of the representative correlation variables u and v are maximized. By transforming the problem of finding the maximum correlation in the CCA method, the input actual signal X may be compared with the analog reference signal Y, and an optimal solution may be found. The overall process can be simplified to a prediction by finding a solution to the following objective function:

since typical relevant variables are:

the method can be simplified as follows:

CCA inputs two groups of multichannel signals X and Y, and outputs weight vector quantity W_xAnd W_yAnd the typical dependent variables u and v. Finding the typical correlation variables u and v and the weight vector can compare the correlation between the input actual signal X and the correct reference signal Y to obtain the identification accuracy.

The brain-computer interface cooperative detection system based on the virtual reality head-mounted display developed by the embodiment of the invention is combined with the visual steady-state evoked potential detection system, so that the luminous environment of the virtual reality display can be fully utilized, and purer, portable and more accessible binocular vision stimulation can be given. Except that the virtual reality system displays images which are richer and have depth information, the advantages of double independent rendering display screens in the existing virtual reality technology are fully utilized, stimulation pictures are independently processed, light paths in life are restored and displayed by using virtual reality scenes, and the effects of detection on visual functions, stereoscopic vision and the like are achieved. Meanwhile, algorithms such as correlation analysis and Fourier transform are utilized, signals which most directly represent cortical reaction can be extracted, and the method has the advantage of high time resolution.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several equivalent substitutions or obvious modifications can be made without departing from the spirit of the invention, and all the properties or uses are considered to be within the scope of the invention.