JPH0233380B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for recording brain waves, and in particular, by creating a brain wave graph consisting of electric potential and each electrode site and recording brain waves in the form of a two-dimensional image, the present invention can be easily and intuitively and visually recorded. This relates to a method of recording brain waves that has made it possible to understand [Prior Art] Conventionally, electroencephalograms are generally produced by recording changes in electrical activity exhibited by the brain over time by guiding them from electrodes on the scalp, and approximating them to a sine wave by taking the fluctuating potential difference on the vertical axis and time on the horizontal axis. It is displayed as a waveform curve. The actual recording method is to use an electroencephalograph to greatly amplify the electroencephalogram, as it is a minute electrical potential on the order of microvolts, and to record the vertical movements of the pen tip in waves on a flowing piece of paper. This waveform has a height (amplitude μV)
and the width (duration, period, millisecond), and the frequency (cycle) is 1/period. In order to read brain waves from the waveforms recorded as described above, it is generally accepted that brain waves are drawn at a width of 3 cm per second, so the width of the recorded waveform is within 3 cm. The frequency is determined by measuring with a scale etc. how many percentages it falls into, and the amplitude is determined by measuring the length with a scale and converting it into voltage. [Problems to be solved by the invention] However, in order to read the brain waves, each page of the recorded brain waves must be read, but it takes time to read all the many waveforms.
Although this method reads the parts that represent the overall characteristics of the brain waves and understands the whole picture, accurate reading requires skill, and individual differences make it difficult to make quantitative judgments. On the other hand, we have recently performed additive analysis of electroencephalogram evoked potentials using a computer, and developed color graphics.
Some methods have been used to display potentials on CRTs in different colors for patterns. For example, in Japanese Patent Application Laid-Open No. 57-52436,
An electroencephalogram data processing method is disclosed in which, for each frequency band, the intensity distribution of the power spectrum is sequentially displayed in a color image at a certain time interval in a figure having an outline imitating a cross section of the brain. In this method, the intensity distribution of the power spectrum of brain waves is color-coded, making it easy to understand, and temporal changes can be observed in near real time.
Because the intensity distribution is displayed in color, it is macroscopic and not quantitative, and intensity comparisons are indistinguishable.Also, there is no data index that can be used as a reference value, and the normal values of the brain waves of a normal person and the examiner's The drawback was that it was not possible to compare brain waves on the screen. In addition, in Japanese Patent Application Laid-open No. 141878/1983, time series data of brain waves is processed by fast Fourier transform method, and the power spectrum of each brain wave derivation site is plotted in a graph where the vertical axis represents the relative power and the horizontal axis represents the frequency. it's shown. In this method, a graph of the number of channels ( _number of leads) is created, and it is possible to compare the intensity of _the power spectrum of each brain wave derivation site in the head _. It is not possible to compare the electroencephalogram potential for each frequency band of _{the two} waves, and there is no data index that can serve as a reference value, so it is difficult to compare the normal electroencephalogram values of a normal person and the examiner's electroencephalogram on the screen. There was a drawback that I couldn't do it. The present invention was completed as a result of research in view of the fact that the above-mentioned brain wave analysis is very difficult even for experts, and even if the general public shows brain waves and explains the waveforms, it is difficult to understand. It is a thing,
By displaying brain waves in a line graph for each frequency band of δ, θ, α ₁ , α ₂ , β ₁ , β ₂ with the vertical axis representing potential and the horizontal axis representing each electrode site, you can quantitatively and intuitively It measures accurately and compares the normal brain waves of a normal person with the brain waves of the examiner on the screen, making it easier to explain and understand brain functions to the general public, and to understand the differences between the functions of the left and right sides of the brain. The purpose of this invention is to provide a method for recording brain waves that can be easily compared quantitatively. [Means for Solving the Problem] and [Operation] That is, the present invention converts an analog brain wave signal measured by an electroencephalograph into a digital signal using an interface device, and converts the digital signal using a personal computer. In the brain wave recording method that performs calculations and displays graphs on the screen, the analog brain wave signals from each electrode site input from the electroencephalograph are captured for a certain period of time and converted into digital signals, and the captured data is calculated using the fast Fourier transform method. The power spectrum is calculated and displayed on a graph for each electrode site with the vertical axis representing potential and the horizontal axis representing frequency.Then, the power spectrum is plotted for each electrode site and δ,
Analysis is performed for each frequency band of the θ, α ₁ , α ₂ , β ₁ , and β ₂ waves, and for each frequency band, the vertical axis is the potential, and the horizontal axis is the symmetrical electrodes on the left and right sides of the brain where the electrodes are attached. This is an electroencephalogram recording method in which a pair of regions is displayed on a line graph consisting of each electrode region with a sequential scale, and a line graph of normal values of the electroencephalogram is simultaneously displayed on the screen or hard-copied to a printer. The present invention will be explained in detail below. First, a recording device used in the electroencephalogram recording method of the present invention will be explained. The recording device sends 12 or 16 channels of biological signals input from electrodes to a personal computer via an interface device for analysis, and automatically records brain waves based on the results. FIG. 1 is a block diagram showing an example of an electroencephalogram recording apparatus according to the present invention. In FIG. 1, the electroencephalograph measures brain waves at each electrode site and displays the measured data as an analog signal. For electroencephalogram measurements, electrodes are attached using the monopolar induction method with 12 or 16 channel inputs that comply with the international 10-20 method. Moreover, a commercially available electroencephalograph can be used. A specific example is the electroencephalograph model 1A72 manufactured by Sanei Sokki. A personal computer is connected to the recorder output terminal of the electroencephalogram via an interface device. In the present invention, the interface device performs the function of converting the analog signal displayed by the electroencephalograph into a digital signal and sending it to the personal computer. The interface equipment consists of a 12CH multiplexer, preamplifier, 12bit AD converter, intelligent control unit, RS232C unit, etc. The 12CH multiplexer is a device that switches 12 channels of input into one channel-by-channel input and captures analog signals from the electroencephalograph. The switching time is 50μSEC. The preamplifier amplifies the signal captured by the 12CH multiplexer. The 12bitA-D converter (AD converter) converts the analog signal obtained from the preamplifier into a digital signal. The intelligent control unit (data acquisition control device) controls the 12HC multiplexer, switches channels, operates the A-D converter, captures data for 12 channels, controls the RS 232C unit, and outputs the data to a personal computer (Panafacom). C-7000D). The RS232C unit is an interface that complies with the RS232C standard, and is a connector that connects the interface device and a personal computer. Next, an example of the specifications of the interface device used in the present invention is as follows: Input channels: 12 channels, Input impedance: 100KΩ, A/D conversion time: 200 μ/sec, A/D conversion accuracy: 12 bits. FIG. 2 shows a circuit diagram of the interface device. In the present invention, the personal computer is
It is connected to the interface device, and the measurement data of the digital signal sent from the interface device is calculated by the fast Fourier transform method to obtain the power spectrum, and the power spectrum is calculated for each electrode site and δ, θ, α ₁ , α Analyzes are performed for each frequency band of _{the 2} , β ₁ , and β ₂ waves, and for each frequency band, the vertical axis is the potential, and the horizontal axis is the symmetrical electrode site on the left and right sides of the brain where the electrodes are attached, and is sequentially scaled. is displayed on a line graph for each electrode location. A personal computer consists of a computer main body, a color display, a keyboard, a 10MB fixed disk device, a printer, etc. A specific example of a personal computer used in the present invention is an OA personal computer C
-7000D, memory 256KB to 384KB. Next, the specifications of the personal computer used in the present invention are as follows. Γ Computer main body memory capacity ROM 8K bytes RAM 384K bytes Color CRT output 640 x 480 dots Palette function Simultaneous 8 color display Printer output 24 x 24 dots 120CPS Calendar clock Built-in power supply AC100V±10% Power consumption 0.9KVA Weight 23Kg Size 480 (W) ) × 445 (D) × 165 (H) mm Γ color display section CRT 12-inch display color 83-color screen configuration including three primary colors, 8 colors, and intermediate colors Graphics screen × 9 + character screen Power supply AC100V ± 10% Power consumption 90VA or less Weight 12Kg Size 320 (H) x 415 (D) x 347 (W) with tilt stand Number of display characters 80 characters x 24 lines x 9 screens Γ Keyboard key arrangement Standard JIS (with numeric keypad) Output data JIS 8-bit code (parallel) Weight 2.3Kg Γ10MB fixed disk storage storage capacity 10MB data capacity 1000 peopleΓPrinter print speed 80 characters/second printing method Dot matrix impact bidirectional printing Number of prints 80 characters/line 66 lines/page Power supply AC100V±10% Power consumption 120VA Weight 16Kg Size 570 (W) x 455 (D) x 175 (H) Next, a method of recording brain waves of the present invention using the above-mentioned brain wave recording device will be explained. FIG. 3 is a flowchart showing a method for recording brain waves. In FIG. 3, 12 channels of measurement data input from an electroencephalograph are first input into a personal computer via an interface device. The measurement conditions are set such that the time for one capture is fixed at 5 seconds (4.88 msec x 1024), and the number of captures ranges from 1 to 99 times. Next, the number of acquisitions is set, and the electroencephalogram is connected to the personal computer C via the interface device.
-Stores measurement data in the 7000D's main memory in real time. Number of channels: 12 Channel sampling clock: 4.8ms Number of sampling: 1024 points/channel The time series data stored in the main memory is converted into a complex Fourier series using the fast Fourier transform method (FFT), and the power spectrum is calculated. FFT calculation accuracy 32 bits Frequency resolution 0.5Hz Frequency band 0~80Hz The power spectrum obtained as a result of calculation is stored on a fixed disk. Power spectrum calculation is performed on the sampled data every 5 seconds, and the process of storing the results is repeated a set number of times. When the power spectra for the set number of times are stored, the average power spectrum divided equally by the number of times is stored.
Simultaneously on one screen for each electrode site of 12 channels,
Displayed in a graph with the vertical axis representing potential and the horizontal axis representing frequency. Next, the above power spectrum is calculated for each electrode site (channel) and for δ, θ, α ₁ , α ₂ , β ₁ , β ₂
Each frequency band of each wave is written to a measured value master file on a fixed disk, and this measured value master file is read and analyzed to create a potential distribution diagram for each frequency band, and for each wave number band, the vertical axis is the potential ( 0 to 50 μV), and the horizontal axis represents a pair of symmetrical electrode sites on the left and right sides of the brain to which the electrodes are attached, and each electrode site (channels 1 to 12) is displayed on a line graph (SS graph) with a sequential scale. Each electrode site on the horizontal axis is marked with 12 scales corresponding to the number of channels, and the scales are arranged sequentially with pairs of symmetrical electrode sites on the left and right sides of the brain to which the electrodes are attached. For example, as shown in FIGS. 4 and 5, FP ₁ , FP ₂ , F ₇ , F ₈ , C ₃ , C ₄ ,
Arrangements of T ₅ , T ₆ , O ₁ , O ₂ , Fz, and Pz are preferred. Frequency band division δ wave 2.0~3.8Hz θ wave 4.0~7.8Hz α ₁ wave 8.0~9.8Hz α ₂ wave 10.0~12.8Hz β ₁ wave 13.0~19.8Hz β ₂ wave 20.0~29.8Hz Potential distribution diagram and SS graph, By specifying the number from the menu screen, the measurement value master file is read and displayed in color on the CRT screen.
Or perform the process of printing out a hard copy on a printer. Using the above-mentioned method of displaying on a line graph, a line graph of the normal values of the brain waves of a normal person is measured and obtained in advance, and a line graph of the normal values and a line graph obtained by measuring the examiner's brain waves are displayed at the same time. The brain waves of a normal person and those of the examiner are compared by displaying it on a screen or by printing a hard copy on a printer. In this manner, brain waves can be recorded in an electroencephalogram graph in which the vertical axis represents the electric potential and the horizontal axis represents each electrode site as a line graph. [Example] Next, the present invention will be described in more detail with reference to Examples. Example 1 A personal computer (Nanational,
Using a device connected to a Panahuacom C-7000D), brain waves were recorded according to the processing procedure shown in Table 1. Furthermore, Table 2 shows an overview of the menu numbers.

【table】

【table】

[Table] [Processing procedure] Input of Γ examiner data When menu No. 1 is selected from the menu screen, the following items will be displayed on the screen. Measurement data is collected by specifying the NUMBER of the examiner. (1) NUMBQR (2) NAME (3) AGF (4) DATE Enter from keyboard (5) TIME Enter automatically (6) NOTE Enter comment from keyboard (7) Band name and band display Γ EEG measurement Electroencephalogram Data is automatically collected from and displays date and time. The number of acquisitions is collected by specifying the COUNT number.
Next, the start of calculation and the display of the calculation in progress are performed.
The calculation is performed repeatedly by capturing the signals of all channels for 5 seconds, calculating the power spectrum, and adding it to the previously determined power spectrum. You can calculate up to 20 counts with 1 count for 5 seconds, and you can specify any number of counts. The import start time is automatically displayed, and the import end time is automatically displayed. Γ Power Spectrum Graph Select Menu No. 2 from the menu screen to display the power spectrum graph screen.
The power spectrum results for 12 channels are displayed. Power on the vertical axis, frequency 0 to 80 on the horizontal axis
Hz, one division of 5 Hz is displayed. Calculation and count numbers are displayed. Γ Potential distribution diagram Select menu No. 3 from the menu screen to display the potential distribution diagram screen. Displays a potential distribution diagram for each frequency band. In this case, the magnitude of the potential of the power spectrum is divided into six levels and each potential is compared and displayed by pattern and each frequency band by color. Delta band (blue) Frequency 2.0~3.8Hz Theta band (purple) Frequency 4.0~7.8Hz Alpha band (red) Frequency 8.0~12.8Hz Beta band (green) Frequency 13.0~29.8Hz ΓS.S graph From the menu screen, select Menu No. If you select .4, a screen will be displayed. Specify Y if you want to display the normal person graph, or N if you do not. The normal human graph shows the following: Minimum value to maximum value White Average value Black The average potential of each channel obtained by calculation is displayed as a line graph with the vertical axis representing the potential and the horizontal axis representing each electrode site. You can enter a graph of a normal person and compare it with graphs for each age group from 20s to 60s. (A graph by age is displayed according to the age of the examiner.) Six frequency bands δ, θ, α ₁ , α ₂ , β ₁ , and β ₂ are displayed simultaneously. It is possible to display four times: red for the first time, yellow for the second time, green for the third time, and blue for the fourth time, for comparison and consideration. In addition, a normal person graph is displayed on the SS graph, allowing you to compare and examine the examiner's data. ΓS.S graph Select menu No. 5 from the menu screen to display the screen. If you want to display the normal person graph, specify Y, otherwise specify N, and specify the frequency band with NO. From the SS graph, δ, θ, α ₁ , α ₂ , β ₁ , β ₂ ,
It is possible to select and display one arbitrary frequency band for each of the following. From the SS graph, a display of the SS graph in the δ wave band is shown in FIG. From the SS graph, display the normal person graph,
It is possible to compare the examiner's delta wave bands. The results are shown in FIG. List of potentials by frequency band When menu No. 6 is selected from the menu screen, a screen with measurement data values for 12 channels will be displayed for each frequency band. Displays a list of potentials for the examiner's four tests. ΓS.S graph When you select menu No. 7 from the menu screen, a screen will be displayed where the vertical axis is potential and the horizontal axis is time. It is possible to measure the time course of biopotential and observe its function. Registration of Γ Examiner Select menu No. 8 from the menu screen and the screen will be displayed. Select No. to register and modify the examiner's name, date of birth, and gender. Registration of Γ normal person graph Select menu No. 10 from the menu screen and the normal person screen will be displayed. Specify the frequency, average value for every 12 channels,
Register maximum and minimum values. [Effects of the Invention] As explained above, the electroencephalogram recording method of the present invention records electroencephalograms in each frequency band of δ, θ, α ₁ , α ₂ , β ₁ , and β ₂ waves, with the vertical axis representing electric potential and the horizontal axis representing potential. Since the axes are displayed and recorded in a line graph at each pole, there are excellent effects as described below. (1) Measure the brain waves of normal people between the ages of 20 and 60,
A line graph of the brain waves of a normal person is created based on the electric potential for each frequency band, and based on this, clinical brain wave detection in the field of psychiatry is performed. By comparing how much the examiner's brain waves deviate from the brain wave pattern of a normal person, it is easy to explain and understand the function of the brain to the general public, and to find out how much the brain waves of the examiner deviate from the brain wave pattern of a normal person. Of course, it can be applied to testing the brain functions of ordinary people and other areas. (2) EEG is displayed on a line graph consisting of each frequency band, with the vertical axis representing the potential and the horizontal axis representing each electrode site with a sequential scale, with the left and right pairs of electrode sites on the brain to which the electrodes are attached as a pair. Therefore, the difference in function between the left and right sides of the brain can be easily compared quantitatively. (3) Since the recording of electroencephalogram potential is displayed as a line graph, it is possible to measure electroencephalograms more accurately and quantitatively, compared to the conventional method in which the intensity distribution of electroencephalogram potential is displayed in color. Can be done. (5) EEG recording can be performed automatically by a program.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a device used in the electroencephalogram recording method of the present invention, FIG. 2 is a circuit diagram of an interface device, FIG. 3 is a flowchart showing the electroencephalogram recording method, and FIG. Figure 5 is a line graph showing a comparison of the δ waves of the examiner and a normal person.

Claims (1)

[Claims] 1 In an electroencephalogram recording method in which an analog brain wave signal measured by an electroencephalograph is converted into a digital signal by an interface device, the digital signal is calculated by a personal computer, and displayed as a graph on a screen. Analog brain wave signals from each electrode site are captured for a certain period of time and converted into digital signals, and the captured data is calculated using the fast Fourier transform method to obtain the power spectrum.The vertical axis is the potential and the horizontal axis is the frequency for each electrode site. The power spectrum is then displayed on a graph for each electrode site and for δ, θ, α ₁ , α ₂ , β ₁ ,
Analyzing each frequency band of the β ₂ wave, the vertical axis is the electric potential for each frequency band, and the horizontal axis is each electrode with a scale sequentially set as a pair of symmetrical electrode sites on the left and right sides of the brain where the electrodes are attached. A method of recording brain waves in which a line graph of normal brain wave values is displayed on the screen at the same time as a line graph consisting of the body parts, or a hard copy is printed on a printer.