TWI492084B - Cerebral wave visual evoked potentials - Google Patents

Description

Brain wave visual evoked potential stimulation method

The invention relates to a method for stimulating a brain wave visual evoked potential, in particular to a stimulating method for performing visual evoked potential stimulation with a coding principle of stimulation time point, so as to shorten the option stimulation period and improve the correct rate.

After the human body receives visual stimulation, its signal passes through the optic nerve and into the occipital lobes of the brain, causing a series of changes in electrical activity. These changes in electrical activity are called visual evoked potential (VEP). Generally, a flash or alternating checkerboard pattern is used as a visual stimulus source, and the brain wave signal generated by the induction can be recorded as a basis for clinical diagnosis.

With the development of brainwave signal acquisition technology in recent years, visual evoked potentials have also been applied to the brainwave human-machine control interface. By visually evoked potentials, the user's brainwave signals can be used to allow users to transmit through brain waves. The idea achieves the purpose of controlling the external device in real time. The brain wave human-machine control interface can benefit patients such as central nervous system damage, limb disorders or hypoplasia, myasthenia gravis or stroke of the brain, which helps these patients communicate with the external environment.

The visual stimulation method of the earliest brainwave human-machine control interface is irregular. It is usually to directly visually stimulate the user to randomly generate the stimulation time point. Since the interval of each stimulus is at least 300. Milliseconds (ms), which is not only time-consuming and inefficient. Therefore, the current visual stimulation method generally adopts the control panel row and column alternate manner for stimulation. As shown in FIG. 1 , the control panel 1 of 4 rows and 3 columns is taken as an example, and the control panel 1 has twelve display areas. 11, each display area 11 has different signals for the user to look at, the number above is used to indicate the stimulation time point of each signal flashing (unit: 100 milliseconds), and the blank interval of the row and stimulus conversion is 500 milliseconds. After each row and the stimulation time point are stimulated four times respectively, it takes 5.5 seconds to complete an option stimulation cycle, thereby stimulating the above-mentioned random stimulation, completing the short-term efficiency of a stimulation cycle, and Shorten the operating cycle, but there is still room for improvement.

In addition, the Republic of China Patent Publication No. 591481 discloses a "visual drive control system and method". The main technical means of the visual drive control method is that each display area is divided into bright and dark flicker signals by a fixed time period. The difference in the order of arrangement of the optical signals by each stimulation period corresponds to different instructions; the case is proposed in the second preferred embodiment, in each 1 second period, by 10 time intervals of 0.1 second each. Arranged, such as the flashing signal of command A is 1010110011, the blinking signal of command B is 101011110, etc., 1 means that the command option of the display area will produce a flashing at this time point, and 0 will generate no flickering stimulus through a series of optical signals. The flicker stimulates the eye, and then transmits to the brain to generate a brain wave signal related to the scintillation signal, and then analyzes the correlation between the brain wave signal and the blinking timing of each blinking signal through the system, and finally interprets and transmits the control signal. However, although the control method can achieve the purpose of control and communication according to this, the disadvantage is that when a plurality of different instructions send the array blinking signals in a fixed sequence of time in a fixed time period, once the signal flicker stimulation interval is too Short (for example, less than 200 milliseconds), the two consecutive flickering stimuli will cause interference, and the error rate will increase; in addition, the flicker signal codes between different display areas are too close, which may cause confusion due to the superb overlap of the flicker signals. In the wrong situation, if the second preferred embodiment of the case proposes that 10 0.1 second blinking signals constitute a fixed stimulation period of 1 second, the command A and the command B have the same 7 blinking time points (101011xx1x); Since the control method is easy to perform visual stimulation, it is easy to confuse the interpretation because the time of the scintillation stimulation is too close, and there is a need for further improvement.

In view of the above, the present inventors have developed and designed the present invention after continuous research, experimentation, and improvement in view of the aforementioned shortcomings in accordance with the techniques of psychological testing, brain neuroscience, and information engineering.

The technical problem to be solved by the present invention is to overcome the visual evoked potential stimulation method adopted by the conventional brain wave human-machine control interface, which cannot simultaneously have the shortcomings of the short stimulation period and the high accuracy rate. The object of the present invention is to provide a brain wave stimulation method capable of greatly shortening the option stimulation period, and more particularly to a brain wave vision evoked potential stimulation method which has both a short stimulation time period and a high accuracy rate.

In order to achieve the foregoing object, the technical problem of the present invention is achieved by the following technical solutions. According to the present invention, a "stimulation mode of brain wave visual evoked potential" is proposed. First, the brain wave electrode patch is adhered to the electrode position of the user's optic nerve region, and N200 is used (for 160 milliseconds to 210 milliseconds after stimulation). The maximum potential difference between the minimum negative potential) and P300 (the maximum positive potential between 260 milliseconds and 310 milliseconds after stimulation) (referred to as N2P3 or P300-N200 potential) is used as the basis for the control target; then, a stimulus source is provided for the user Gaze, the stimulus source is a control panel having a plurality of display areas, each display area has a stimulus signal that is different from each other, and each of which has a blinking duration of about 20 to 30 milliseconds for corresponding command options. The stimulation signals are flashed at different intervals for at least four times to complete an option stimulation period. In each stimulation period, the stimulation time points of any two display regions can be at most 25% or less at the same time to avoid a confusing effect, and Each display area of each row has the same stimulation time point to enhance the stimulation effect; and in each display area, the stimulation signal flashes between The interval must be at least 200 milliseconds or more; finally, after each display area accumulates its own brain wave signal, the brain wave signal exhibiting the maximum N2P3 potential difference is used, and the command option corresponding to the display area is used as an output item.

In summary, the advantages and effects of the present invention are that, through the clinical experiment process, the above-mentioned steps can greatly shorten the option stimulation period, and can improve the correct rate of the brain wave visual evoked potential to over 95%, thereby being effective. It has the disadvantages of improving the conventional visual evoked potential stimulation method and has excellent practical effects.

1. . . control panel

11. . . Display area

2. . . control panel

twenty one. . . Display area

S1. . . First brain wave signal

S2. . . Second brain wave signal

S3. . . Integrate brainwave signals

S4. . . First brain wave signal

S5. . . Second brain wave signal

S6. . . Integrate brainwave signals

Figure 1 is a timing diagram of the control panel stimulation time point of the conventional row and row stimulation.
2 is a timing chart showing the stimulation time point of the control panel according to the preferred embodiment of the present invention.
Figure 3 is a combined brain wave signal generated by a two-stimulus time interval of 100 milliseconds.
Figure 4 is a combined brain wave signal generated by a two-stimulus time interval of 200 milliseconds.

The following is a detailed description of the specific embodiments and reference drawings, and it is easier to understand the technical contents, operational features and effects achieved by the present invention.

The invention relates to a method for stimulating brain wave visual evoked potentials. Firstly, the brain wave electrode patch is adhered to the electrode position of the user's optic nerve region, and the electrode position can be configured and attached according to the electrode position of the international standard 10-20 system. The maximum potential difference between N200 and P300 is used as the basis for the control target; N represents the negative potential, N200 is the minimum negative potential between 160 milliseconds and 210 milliseconds after stimulation; P represents the positive potential, and P300 is 260 milliseconds to 310 after stimulation. The maximum positive potential between milliseconds, and the maximum potential difference between N200 and P300 is to reduce P300 by N200, referred to as N2P3 or P300-N200 potential.

Then, a stimulus source is provided for the user to gaze. The stimulus source may be a control panel 2 having a plurality of display areas 21 in a checkerboard shape, wherein each display area 21 has stimulation signals that are different from each other to be displayed. Different command options, the stimulation signals generate blinking at least four times at different time intervals, completing an option stimulation cycle, and in each option stimulation cycle, the stimulation time of any two stimulation signals can only be up to 25% or less. In order to avoid the confusing effect, and experimentally found that each display area 21 of each row has the same stimulation time point, which can effectively increase the stimulation effect.

Referring to FIG. 2, a preferred embodiment of the present invention discloses a control panel 2 that presents four rows and three columns. The control panel 2 has twelve display areas 21, and the numbers of the display areas 21 are used for The stimulation time point (unit: 100 milliseconds) indicating that the stimulation signal is blinking, and the stimulation time point of any two display areas 21 is at most 25% identical. According to the preferred embodiment, twelve display areas 21 are known. The stimulation signal of each display area 21 is blinking at least four times at different time intervals to complete an option stimulation period, and the last stimulation time point is 15, which means that only one 1.4 seconds (15 minus 1) can complete an option output; And through the experimental process, the correct rate of this method is over 95%. Of course, in actual implementation, the number of rows and columns of the control panel 2 is not limited to 4 rows and 3 columns, and the stimulation time point of each display region 21 is based on the aforementioned stimulation time coding principle: the stimulation signal of any two display regions 21 is presented. The stimulation time point is up to 25% identical, and the computer program can be used to find the shortest stimulation time point arrangement.

Furthermore, flicker visual stimuli must be generated in each display area with a stimulation time interval of at least 200 milliseconds, wherein the stimuli signal is maintained for approximately 20 to 30 milliseconds per blink. At least 200 milliseconds or more will be used as the stimulation interval, mainly because the experiment repeated by the inventor found that when the stimulation interval is less than 200 milliseconds, the brain wave signals generated by the user will interfere with each other and offset the potential difference of N2P3. , which in turn increases the error rate.

Please refer to FIG. 3 , which is a combined brain wave signal generated by the second stimulation time interval of 100 milliseconds, wherein the first brain wave signal S1 and the second brain wave signal S2 are visually stimulated by the user at intervals of 100 milliseconds. It will be found that the maximum potential difference (N2P3) of the first brain wave signal S1 and the second brain wave signal S2 is combined into the integrated brain wave signal S3, and the amplitude is obviously offset by the interference.

Please refer to FIG. 4 again, which is a combined brain wave signal generated by the second stimulation time interval of 200 milliseconds, wherein the first brain wave signal S4 and the second brain wave signal S5 are visually stimulated by the user at intervals of 200 milliseconds. At this time, it is found that the maximum potential difference (N2P3) of the first brain wave signal S4 and the second brain wave signal S5 is combined into the integrated brain wave signal S6 with a fairly significant N2P3 amplitude, and does not interfere with each other.

Finally, after each display area 21 accumulates the brain wave signal of the area, the integrated brain wave signal S6 exhibiting the maximum potential difference (N2P3) amplitude is used, and the integrated brain wave signal S6 corresponds to the command option of the display area 21 as an output item. Achieve the purpose of brain waves to control external things; through actual clinical experiments, it is proved that the above steps can significantly shorten the stimulation cycle and increase the correct rate of brain wave visual evoked potentials to over 95%, thereby effectively improving the conventional vision. The shortcomings of the evoked potential stimulation method have excellent practical effects.

The above is only the preferred embodiment of the present invention, and it is intended to enable those skilled in the art to understand the contents of the present invention and is not intended to limit the scope of the present invention; Equivalent changes or modifications of the technical means and spirit of the invention are intended to be included in the scope of the invention.

2. . . control panel

twenty one. . . Display area

Claims (2)

A method for stimulating a brain wave visual evoked potential, firstly, attaching an electroencephalogram electrode patch to an electrode position of a user's optic nerve region, and using a maximum potential difference between N200 and P300 as a basis for controlling the target; and then providing a The stimulating source is for the user to look at. The stimulating source is a control panel having a plurality of display areas, and each of the display areas has stimulating signals that are different from each other for different command options, and the stimulating signals are at different time intervals. Generate a scintillation stimulus at least four times to complete an option stimulation cycle. In each option stimulation cycle, the stimulation time points of any two display zones can be at most 25% or less at the same time to avoid confusion effects, and each row of In each display area, the last stimulation time point is the same to increase the stimulation effect; and in each display area, the stimulation signal blink interval must be at least 200 milliseconds or more; finally, each display area is accumulated after the brain wave potential signal of the area a brain wave signal exhibiting a maximum potential difference between the two potentials of N200 and P300, and an instruction corresponding to the display area The option is used as an output item; this can effectively shorten the option stimulation cycle and improve the accuracy rate, so as to achieve the purpose of brain waves controlling external things. The method for stimulating brain wave visual evoked potential according to claim 1, wherein N200 is a minimum negative potential between 160 milliseconds and 210 milliseconds after stimulation; and P300 is a maximum positive potential between 260 milliseconds and 310 milliseconds after stimulation. .