JP3141014B2 - Brain wave topography display gradation setting method and brain wave topography display gradation setting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting a gray scale of an electroencephalographic display and a device for setting a gray scale of an electroencephalographic display.

[0002]

2. Description of the Related Art As an electrode arrangement used in an electroencephalograph, an international electrode arrangement method (10-20 method) as shown in FIG. 5 has been conventionally known.

FIGS. 5A to 5E show an electrode arrangement procedure viewed from the front upper surface of the head. First, (a) a nose root, ie, a median portion and an occipital pole on an anterior forehead suture line; 5A, the median line along the skull surface connecting the intersection of the line of the demarcation term of the occipital bone and the median sagittal plane is 10%, 20%, 20%, 20%, 20% as shown in FIG. 5A.
%, 10%, and FP _Z , F _Z ,
Let C _Z , P _Z , O _Z. (B) Crossing lines along the head surface passing through the C _Z point and connecting the left and right pre-auricular points (recesses at the root of the cheekbone in front of the tragus) are shown as 10%, 20%, and 20% as shown in FIG. 5B. %, 20%, 20%,
10%, T ₃ , C ₃ , C _Z , C ₄ , T
_{And 4} . (C) The total length of the coronal line connecting FP _Z and O _Z passing through T ₃ is 10%, 20%, 20%, 20%, 20%, as shown in FIG. 5C.
It is divided into 10%, and FP ₁ , F ₇ , T ₃ , T ₅ , and O _{1 in} the right hemisphere from FP _Z on the root side of the nose. (D) The total length of the inner coronal line passing through C ₃ and connecting FP ₁ and O ₁ is divided into four equal parts in the right hemisphere as shown in FIG. 5D, and these are defined as F ₃ , C ₃ , and P ₃ from the front. . (E) In the left hemisphere, by performing the same procedure as (c) and (d), FP ₂ , F ₈ , T ₄ , T ₆ , O ₂ and F ₄ ,
By setting C ₄ and P ₄ (see FIGS. 5C and D), electrodes were arranged at each point as shown in FIG. 5E, and the electroencephalogram measurement was performed.

In a clinical electroencephalography at the time of measuring an electroencephalogram using such an electrode, a rhythmic α-wave of 8 to 13 Hz, a σ-wave called slow wave, a β-wave of continuous wave, and a β
There are waves, and their changes and physiological changes are widely used to obtain the causes of organic and functional diseases.

[0005] In order to visually observe the distribution of the frequency components of the brain wave waveform induced from a plurality of electrode groups arranged on the head as described above, a topographic display has been conventionally performed.

[0006]

In the above-mentioned conventional method of setting the distribution gradation of the topographic display, the absolute value of each color of the distribution gradation is obtained, and the color is displayed by classifying it into, for example, 16 gradation classes. I was

However, when the data (amplitude) of the brain wave waveform greatly changes, the gradation must be changed each time as shown in FIG.
In many cases, it is not possible to display a clear distribution as shown in FIG.

In order to solve such a problem, a method of setting the maximum value and the minimum value of the electroencephalogram data and setting a gradation between them has been used in the related art. Even if one of the plurality of electrode groups described with reference to FIG.
When a large amplitude change or the like is generated, the entire gradation is dragged by the value of the electrode. For example, even if the topography display is performed after adjusting the gradation of the electroencephalogram waveform data, FIG. In many cases, the overall distribution was not clear.

An object of the present invention is to normalize data by calculating an average value and a standard deviation from a potential induced from an electrode, to automatically set a gradation of a topographic display, and to obtain a distribution of a topographic display. Is to clarify.

[0010]

According to the present invention, there is provided an electroencephalogram topography display gradation setting method, comprising: calculating an average value from a plurality of digitized electrode data obtained by digitizing electroencephalogram signals extracted from a plurality of electroencephalogram electrodes; Standard deviation value calculation step for calculating standard deviation value from multiple digitized electrode data, and normalization of multiple electrode data from average value calculated in average value calculation step and standard deviation value calculated in standard deviation value calculation step A normalization operation step of operating the calculated value;
An interpolation operation step of performing an interpolation operation on a distribution of a portion having no electrode from a plurality of electrode data, wherein the operation result calculated in the interpolation operation step is topographically displayed in a gradation designated by ± standard deviation value. Things.

According to the present invention, there is provided an electroencephalogram topography display gradation setting apparatus, comprising: an average value calculating means for calculating an average value from a plurality of digitized electrode data of an electroencephalogram signal extracted from a plurality of electroencephalogram electrodes; Standard deviation calculation means for calculating a standard deviation value from data, and normalization calculation for calculating a value obtained by normalizing a plurality of electrode data from the average value from the average value calculation means and the standard deviation value from the standard deviation value calculation means. Means, and interpolation calculating means for interpolating the distribution of parts without electrodes from a plurality of pieces of electrode data, and displaying the result of the calculation performed by the interpolation calculating means in a gray scale designated by a standard deviation ± value. It is made by letting.

According to the method and the apparatus for setting the gradation of the electroencephalogram topography display of the present invention, it is possible to automatically adjust the gradation and obtain a clear distribution.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for setting a gray scale of an electroencephalographic display and a device for setting a gray scale for an electroencephalographic display according to the present invention will be described with reference to FIGS. FIG. 1 is a flowchart of a method for setting a gray scale of an electroencephalographic display according to an embodiment of the present invention, FIG. 2 is a system diagram of a gray scale setting device for an electroencephalographic display according to an embodiment of the present invention,
FIG. 3 is a pattern illustrating an electrode interpolation method, and FIG. 4 is a pattern illustrating an example of a topography display with automatic gradation.

First, before explaining the operation of the flowchart of the present invention, a brain topographic display gradation setting device of the present invention will be described with reference to FIG.

In FIG. 2, reference numeral 1 denotes a human head, and a plurality of electrode groups 2 are arranged above the head by, for example, the 10-20 method described with reference to FIG.

Electroencephalogram measurement potentials from the plurality of electrode groups 2 are supplied to an analog-to-digital converter (ADC) 5 via an amplifier 3 and a multiplexer 4, and digitized measurement potentials are supplied to a computer (an input port 6). Below CPU
9).

The CPU 9 has a control unit and an operation unit. An address bus and a data bus 12 are connected to a work RAM 10.
And the ROM 11, the input port 6, and the output port 13.

The input port 6 is connected to an operation unit 7 such as a keyboard and a mouse, and an external storage device 8 storing measured brain waveform data and the like.

The output port 13 is connected to a display device 14 such as a printer or a CRT for recording or displaying the operation result of the CPU 9 and a recording device 15.

The operation of the above configuration will be described with reference to the flowchart of FIG. 1 and the display pattern of the topography of FIG.

[0021] by arranging the electrode group 2 to the head 1 of the subject, as in the first step ST ₁ performs electroencephalogram measurement of each part.

Next, in a second step ST ₂ , an electroencephalogram waveform composed of an analog signal extracted from each electrode is converted into a digital signal through the ADC 5, and converted into a digital signal through the input port 6.
9.

In the third step ST ₃ , the CPU 9 calculates and calculates the average value A from the electrode data used for the topographic display indicating the distribution state based on the following equation (1).

(Equation 1)

In a fourth step ST ₄ , a standard deviation value δ is calculated from the electrode data based on the following equation (2).

(Equation 2)

[0025] Fifth Step ST ₅ in the above (1) and (2) the average value calculated by formula A and the standard value deviation [delta], the value Va obtained by normalizing the electrode data (data _i) in equation (3)
1 is calculated and obtained.

(Equation 3)

[0026] The interpolation operation power value of sites without the head of the electrode on the basis of the computed power values from a limited electrode group 2 to the sixth step ST ₆ in topography display.

In this interpolation operation, the values of the electrodes at the 5 × 5 grid points of the electroencephalogram data described with reference to FIG. However, since the values of all the electrode groups are not normally measured as shown in FIG. 3, if the electrodes that are not measured are denoted by A, B, C, D, E, and F, the following ( The interpolation calculation of the known electrode is performed by the electrode estimation expression shown in Expression 4).

(Equation 4) k becomes 4 because linear interpolation is used.

The value between the grids (electrodes) using this result is calculated using the following linear interpolation formula (5).

(Equation 5) Here, V (x, y) interpolation result data P ₁ number of grids on the horizontal axis P ₂ number of grids on the vertical axis D (n, m) grid point electrode data n number of grid points on the horizontal axis (normally 10) m vertical axis grid Number of points (normally 10) X (nx) Horizontal interpolation formula X (nx) = 1- | nx-ｎ | nx- <1 X (nx) = 0ｘ | nx | ≧ 0 Y (my) Vertical axis interpolation Y (my) = 1− | my− || y | <1 Y (my) = 0 ‥‥ | m−y | ≧ 0.

When the interpolation calculation is completed, a seventh step ST ₇
Whether operations or completion CPU9 determines in the average value returns to the third step ST ₃ if NO, the long normalization computation and interpolation operation is continued while a YES with standard deviation 8
Each expression you interpolation operation proceeds to step ST ₈ color-coded, for example, of 16 stages class specified gradation ± value of the standard deviation value a topography display performed as in FIG. 4, leading to completion.

FIG. 4 is a display example of a head plane in which the electrode data of the present invention is normalized and topographically displayed. This topographic figure is displayed as an absolute value as shown in FIG.
Compared with the case where the gradation is displayed between the maximum value and the minimum value as shown in FIG. Is removed, and the adverse effect that the distribution becomes unclear is eliminated.

The reason is that even if there is some protruding electrode data, the value of the protruding electrode data is reduced by normalization called standard deviation, so that the gradation of the topography pattern can be clarified.

Further, in the present invention, if a gradation is designated in a standard deviation range designated by a ± value such as a δ or 2δ value represented by a Gaussian distribution curve, for example, a color-separated floor is automatically set within this standard deviation range. It is possible to perform a key adjustment and display a topography.

In the above-described method and apparatus for setting the gradation of the electroencephalogram topography display, a case has been described in which the potential of the electroencephalogram data is displayed topographically and the gradation is set. It is obvious that the present invention can be applied to a power value obtained by performing a frequency analysis by a Fourier transform (FFT) or the like, topographically, or various kinds of brain wave data.

[0034]

According to the brain wave topography display gradation setting method and the brain wave topography gradation display device of the present invention, the brain wave data is normalized, and the gradation is automatically adjusted using the standard deviation range as the gradation. Is possible, and even if there is prominent data in the electroencephalogram data, since the gradation is expressed in accordance with the normalized distribution, the topography distribution can be clearly displayed.

[Brief description of the drawings]

FIG. 1 is a flowchart of a method for setting a gray scale of an electroencephalographic display according to the present invention.

FIG. 2 is a system diagram of a gradation setting device for an electroencephalographic display according to the present invention.

FIG. 3 is an explanatory diagram of a gradation setting method of an electroencephalographic topography display and an electrode interpolation method used in the apparatus according to the present invention.

FIG. 4 is a topography display pattern automatically set by the brain wave topography display gradation setting method of the present invention.

FIG. 5 is an electrode arrangement diagram showing a procedure of a conventional international electrode arrangement method.

FIG. 6 is a topography display pattern in which the distribution of the gradation setting method of the conventional brain wave topography display is not clear.

[Explanation of symbols]

2 electrode group, 5 ADC, 7 operation unit, 8 external storage device, 9 CPU, 14 display device

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-52436 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 5/0476

Claims (2)

(57) [Claims] An average value calculating step of calculating an average value from a plurality of digitized electrode data of an electroencephalogram signal extracted from a plurality of electroencephalogram electrodes, and a standard value calculating a standard deviation value from the digitized plurality of electrode data. A deviation calculation step, a normalization calculation step of calculating a value obtained by normalizing the plurality of electrode data from the average calculated in the average calculation step and the standard deviation calculated in the standard deviation calculation step, An interpolation operation step of performing an interpolation operation on a distribution of a portion having no electrode from a plurality of electrode data, wherein the operation result calculated in the interpolation operation step is topographically displayed with a gradation designated by ± of the standard deviation value. A gradation setting method for an electroencephalographic topography display characterized by comprising: 2. An average value calculating means for calculating an average value from a plurality of electrode data obtained by digitizing electroencephalogram signals extracted from a plurality of electroencephalogram electrodes, and a standard means for calculating a standard deviation value from the digitized plurality of electrode data. a deviation calculating means, and the normalized calculating means for calculating a value obtained by normalizing the plurality of electrodes from a standard deviation from the mean value and the standard deviation value calculating means from the average value calculating means, the plurality Interpolating means for interpolating the distribution of parts without electrodes from the electrode data, wherein the result of the operation calculated by the interpolation means is displayed topographically at a gradation designated by the standard deviation ± value. A gradation setting device for electroencephalographic display, characterized in that: