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Abstract

In a method and an apparatus for measuring degree of neuronal impairment in brain cortex, scalp potentials or magnetic fields of a subject are measured by mounting a plurality of sensors on a head of the subject, the measured scalp potentials or magnetic fields are converted into numerical data to obtain a dipolarity at each sampling, mean values of squared errors, within a fixed time interval, between a scalp potential or a magnetic field by an equivalent dipole at a dipolarity peak emergence time and the measured scalp potentials or magnetic fields, or variances of the squared errors from the mean values are obtained for the sensors, and a contour concerning a distribution of the mean values or the variances on a scalp or a brain surface corresponding thereto is mapped as an output. Alternatively, the squares of potentials sensed by the sensors are averaged for several seconds, and variances of these mean values are obtained for numerous reference persons. The mean value and the standard deviation of the variances for a group of the reference persons are obtained, so that the variance of an individual subject is ranked depending on which area of the standard deviation of the group of the reference persons the variance is located. By allocating the values to a brain surface corresponding to the sensors, maps are prepared. By these maps, a local impairment degree of a neuronal function is indicated.

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