JPS61137540A - Apparatus for fabricating and displaying frequency and amplitude distribution map of brain wave - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a brain wave frequency/amplitude distribution map creation/display device for visually displaying brain wave frequency/amplitude distribution information for use in brain diagnosis. be.

[Conventional technology]

Traditionally, in order to elucidate the pathology of brain-related diseases, it has been necessary to perform functional tests as well as organic and morphological tests of the brain. CT) and cerebral angiography technology are rapidly advancing and have become the most important auxiliary diagnostic methods for diagnosing brain tumors, strokes, etc. and determining treatment methods. - In the functional testing of the brain, electroencephalography (EEG) has been used for a long time.
EEG) tests are important and can provide detailed information about brain function that cannot be obtained with CT or cerebral angiography. Therefore, today, diagnosis and treatment policy are often determined by reexamining CT findings and cerebral angiography findings based on electroencephalogram findings and comprehensively elucidating the etiology and pathophysiological mechanisms.

However, it is difficult to intuitively grasp the correspondence between two-dimensionally displayed CT images and cerebral angiography images and conventional electroencephalogram charts recorded with multichannel pen recorders, etc. Electroencephalogram mapping (CTE), which uses a computer to display the amplitude (equivalent potential) distribution of brain waves two-dimensionally
) system has been proposed in recent years, and its usefulness has attracted attention.

In such an electroencephalogram mapping system, the so-called "international TO-20 electrode method" is generally used to place electrodes on the scalp for deriving brain waves, as shown in Figure 2. The positions of the electrodes are displayed by converting them into a two-dimensional orthogonal coordinate system, but usually 12 to 16 of the 19 locations in the figure are simplified (for example, black circles in the figure). In most cases, electroencephalogram recording is performed by selecting the area (indicated by the mark). In the conventional electroencephalogram mapping system that performs two-dimensional display of only the amplitude (potential distribution), first, the power spectrum of the electroencephalogram within a certain period of time derived from each of the above 12 to 16 locations is subjected to fast Fourier transform (FFT). ), and from the results, obtain an equivalent potential defined by the square root of the average power of each frequency band component as shown in Table 1 below, and then perform interpolation calculations based on this equivalent potential. This depicts the potential distribution over the entire scalp for each frequency band component.

Table 1 Band (electroencephalogram base) Frequency range (Hz) CO15~
4.0 θ 4.0~8.0α
8.0-13.0β
13.0-25.0 [Problems to be solved by the invention] In the examination and analysis of brain waves, not only information on amplitude (potential) but also information on frequency has traditionally played an important role. However, conventional electroencephalogram mapping systems such as those described above are not capable of two-dimensional display of frequency distribution.

In addition, when creating an electroencephalogram map of amplitude distribution, if software is used to perform fast Fourier transform of the electroencephalogram signals derived from more than a dozen points, as in the conventional electroencephalogram creation system, a large amount of processing time is required. If you try to process it using hardware, it will be an expensive system. Furthermore, it is conceivable to extend the conventional electroencephalogram mapping system using FFT to a two-dimensional display of the frequency distribution, but as described below, this method is quite different between the frequency analysis method based on a doctor's inspection and the Fourier analysis method. There is a problem.

In other words, brain waves are generally considered to be roughly divided into the behavior of fundamental waves (also called background activity) and the behavior of sudden waves, but when a doctor inspects these fundamental waves, it is possible to determine whether they are the most dominant waves (fundamental wave or principal component). The most important question is which band in Table 1 above, and this is considered first, then the frequency of the fundamental wave is investigated using a method very close to the zero tolerance method, and then its amplitude, scalp The above distribution, appearance pattern, etc. will be examined. - When attempting to visualize the distribution of fundamental waves by two-dimensionally displaying the average behavior of brain waves over several tens of seconds using a conventional electroencephalogram mapping system, Fourier analysis Information including the components will be output. In this regard, based on the results of clinical research to date, it is said that the behavior of component waves other than the fundamental wave in the fundamental wave that is not a sudden wave is extremely unlikely to have any important meaning. It is considered inappropriate to directly provide a two-dimensional display of information to doctors for diagnosis.

This invention was made in view of the above-mentioned circumstances, and its purpose is to display not only the amplitude distribution of brain waves on the scalp (also capable of displaying two-dimensional frequency distribution), but also to be extremely useful for brain wave analysis during inspection by doctors. It is an object of the present invention to provide an electroencephalogram frequency/amplitude distribution map creation and display device that enables close analysis and is significantly simpler and cheaper than conventional ones.

[Failure to solve the problem]

In order to solve the above problems, the present invention includes a variable band filter section that amplifies each brain wave signal of multiple parts output from an electroencephalograph and extracts frequency band components to be analyzed, and a variable band filter a frequency information extraction section for obtaining information related to the frequency of the brain wave signal of each section outputted from the section; an amplitude information extraction section for measuring the amplitude of the brain wave signal; and a band setting for the band filter section. , a computer section that performs image processing for two-dimensionally displaying the frequency distribution and amplitude distribution of the brain waves based on the frequency information from the frequency information extraction section and the amplitude information from the amplitude information extraction section; In the amplitude distribution map creation and display device, the frequency information extraction section converts the electroencephalogram signal into a square wave having the same duration as a positive or negative half cycle of each electroencephalogram signal, and a waveform shaping circuit group. The present invention provides a brain wave frequency/amplitude distribution map creation and display device characterized by comprising frequency information extraction means for obtaining the frequency information from each output square wave.

[For production]

In the electroencephalogram frequency/amplitude distribution map creation and display device of the present invention having the above configuration, the electroencephalogram signals supplied by the electroencephalogram from multiple sites on the scalp of the subject are analyzed in the variable band filter section. The frequency band components are extracted. This frequency band can be selectively set by the computer section. Each brain wave signal from the variable band filter section is input to a frequency information extraction section and an amplitude information extraction section. The frequency information extraction section is composed of a waveform shaping circuit group and a frequency information extraction means, and the waveform shaping circuit group converts the brain wave signals input from the variable band filter section into rectangular shapes having the same duration as the positive or negative half cycle of each brain wave signal. convert into waves,
The frequency information extraction means derives information related to the frequency of the brain wave signal, such as the pulse width (duration) or the number of clocks proportional to the period, from each of these square wave signals and supplies it to the computer section.On the other hand, the amplitude information extraction means From each brain wave signal input to the computer section, amplitude information representing the amplitude/flux of the brain waves, such as an effective value or an average value, is extracted and also input to the computer section.

The computer section performs image processing including interpolation calculations to display the frequency distribution and amplitude distribution of the brain waves in two dimensions on this frequency information and amplitude information, and creates an electroencephalogram map using color classification etc. of the frequency distribution and amplitude distribution. It is displayed on C艮T in real time. Note that the frequency distribution and amplitude distribution can be displayed on separate CRTs, or they can be displayed on a single CRT by switching modes (or even they can be displayed in different areas on the same CRT). good.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the brain wave frequency/amplitude distribution map creation and display device of the present invention will be described in detail with reference to the drawings.

In FIG. 1, a variable band filter section 10 is configured to filter electroencephalogram signals E extracted from multiple locations on the scalp as shown in FIG.
Amplifier groups 11 that amplify EG, variable band filter groups 12 each consisting of a switched capacitor filter (SCF), and a band that generates a clock signal for selectably setting the frequency band of the variable band filter group 12. It is composed of a setting clock signal generation circuit 13. The band setting clock signal generation circuit 13 is a programmable interval timer (PIT; μPD8
253), and each SCF of the bandpass filter group 12 transmits a band setting clock signal having a frequency obtained by dividing a reference clock (CLK) of, for example, 4 MHz by a division ratio selectively set by the subcomputer section 40, which will be described later. By inputting, for example, one of the five bands shown in Table 2 below can be selected.

Table 2 Band (electroencephalogram base) Frequency range (H2) CO05-4
．． 0 θ 4.0 to 8.0 α 8.0 to 13.0 β 13.0 to 25.0 Full band 0.5 to 25.0 The brain wave signal that has passed through the variable band filter section 10 is sent to the frequency information extraction section 2o and are respectively input to the amplitude information extraction section 30.

Each brain wave signal input to the frequency information extraction unit 2o is first processed by a waveform shaping circuit group 2 consisting of, for example, a Schmidt circuit.
1, each brain wave signal is converted into a square wave Ep having the same duration as the positive half period of each brain wave signal, and then input to the gate terminal of each PIT of the pulse width measurement circuit group 22 consisting of a large number of PITs, and the square wave pulse It becomes a control signal for the counting operation of the width measurement reference clock CLK (for example, l MHz). In this way, the number of clock pulses P during the positive half cycle (or negative half cycle is also possible) of the electroencephalogram signal is counted by PIT (see Figures 3 (a) and (b)). Since the positive and negative half-periods can be considered approximately symmetrical,
The clock pulse number P represents a half cycle of the brain wave, and can be used as frequency information for determining the frequency. It should be noted that an embodiment in which the frequency information extraction section 2o uses a zero-crossing detection circuit and calculates the frequency information by counting the number of zero-crossings of the electroencephalogram signal is also possible.

Each brain wave signal input from the variable band filter section 10 to the amplitude information extraction section 30 is full-wave rectified and smoothed by a full-wave rectification circuit group 31 having a first-order lag circuit group, and then sent to an A/D converter 32. It is input as digital amplitude information.

Furthermore, the A/D converter 32 directly A/D converts the brain wave signal input from the variable band filter group 12 and outputs digital waveform information.

The computer section of this embodiment is a subcomputer section 40.
The sub-computer section 4 is composed of a sub-CPU 41.8 kilobytes, an IT ROM 42.2 kilobytes RAM 43, a timer interrupt signal generation circuit 44, an interface 45.46, etc.
o is a PI that outputs a clock signal for filter band setting, as well as initial settings of the frequency information extraction unit 20, amplitude information extraction unit 30, panel control, interrupt control, and communication interfaces with the host computer.
Initial settings of the hardware, such as output of division ratio data to T(13), are first performed. After that, the commands from the host computer section are decoded, and processing is performed according to each command, i.e., the electroencephalogram (EEG) channel to be used, i.e., if 16 channels are used, the frequency information of the brain wave signal for 16 channels, It collects waveform information and amplitude information, controls interrupts thereof, and transfers data to the host computer.

In this sub-computer section 40, a timer interrupt signal generation circuit 44 interrupts the sub-CPU 41 at settable intervals, such as every 10 milliJ seconds, and
For example, the data of frequency information, amplitude information, and waveform information for 16 channels are transmitted via the interface.
For example, the data is transferred to the host computer section 5o in time division at the above-mentioned intervals of 10 milliseconds. The host computer ff150 consists of a host computer 51, an interface 52, 53, a CRT display 54, a printer 55, an auxiliary storage device 56, etc. The host computer ff150 first inputs the number of input brain wave channels, frequency information, and waveform that are set interactively with the user. Data such as sampling period and filter band when collecting information, amplitude information, etc. are transferred to the subcomputer section 4o.

Next, the host computer 51
The frequency of the brain waves of each region is determined from the frequency information sent from 0, and then interpolation calculations are performed based on this frequency data or the same (amplitude information data sent from the subcomputer section) to determine the frequency distribution and amplitude of the brain waves. By performing image processing for two-dimensional display of distribution, C
For example, an electroencephalogram map color-coded into six levels is displayed on the RT Dinu Play 54, and if necessary, the electroencephalogram waveforms of each channel are reproduced and displayed from the above waveform information, and furthermore, these displayed images are printed out by the printer 55. , image information is stored in an auxiliary memory bag such as a magnetic disk @5
6 to be memorized. In FIG. 1, reference numerals 23 and 33 indicate interfaces between the frequency information extraction section 20, the amplitude information extraction section 30, and the subcomputer section 40, respectively.

〔Effect of the invention〕

As described above in detail, the present invention is a simple and inexpensive method that can display both the amplitude distribution and the frequency distribution of brain waves in two dimensions, and can perform an analysis that is very similar to the brain wave analysis performed by a doctor's inspection. A device for creating and displaying brain wave frequency/amplitude distribution maps can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the brain wave frequency/amplitude distribution map creation and display device of the present invention, and FIG. A diagram showing an example of a display format converted into a coordinate system, Figure 3 (al
and (bl is a waveform diagram and a block diagram for explaining the operation of PIT. 1o... variable band filter section, 12... variable band filter group (SCF), 20... frequency information extraction section, 2
DESCRIPTION OF SYMBOLS 1... Waveform shaping circuit group, 22... Pulse width measurement circuit group (frequency information extraction means), 30... Amplitude information extraction section, 31... Full wave rectifier circuit group and first order lag circuit group ( AC/DC conversion circuit group), 32... A/D K converter (amplitude information extraction means), 40... subcomputer section, 50
...Host computer department.

Claims (4)

[Claims] (1) A variable band filter section that amplifies the brain wave signals of multiple parts output from the electroencephalograph and extracts frequency band components to be analyzed; A frequency information extraction section for obtaining frequency-related information, an amplitude information extraction section for measuring the amplitude of the electroencephalogram signal, and a band setting for the band filter section, and frequency information and information from the frequency information extraction section. An electroencephalogram frequency/amplitude distribution map creation/display device comprising a computer section that performs image processing for two-dimensionally displaying the frequency distribution and amplitude distribution of the electroencephalogram based on the amplitude information from the amplitude information extraction section. A group of waveform shaping circuits in which the information extraction section converts the above-mentioned brain wave signals into square waves having the same duration as the positive or negative half period of each brain wave signal, and the above-mentioned frequency information from each square wave outputted from the waveform shaping circuit group. 1. A brain wave frequency/amplitude distribution map creation/display device comprising: frequency information extraction means for obtaining frequency information. (2) A group of AC/DC conversion circuits for the amplitude information extraction section to convert each of the electroencephalogram signals into DC signals, and amplitude information extraction means for obtaining the amplitude information from each DC signal of the AC/DC conversion circuit group. An electroencephalogram frequency/amplitude distribution map creation/display device according to claim 1, characterized in that the device comprises: (3) The frequency information extraction means for the brain waves as set forth in claim 1 is characterized in that each of the frequency information extraction means comprises a gate circuit group that outputs an AND signal of each of the above square waves and a reference clock signal. Amplitude distribution mapping display device. (4) The AC/DC conversion circuit group is a full-wave rectifier circuit group having a first-order lag circuit group, and the amplitude information extraction means is an analog-digital (A/D) converter. The brain wave frequency/amplitude distribution map creation and display device according to item 2.