Abstract
A computer display system of the EEG is presented in order to clarify the relation between the localization of brain lesions and abnormal EEG activities in patients with central nervous system diseases. The system is based upon two parts. One is derivation of an equivalent potential defined as a square root of average power over a desirable frequency band in the power spectrum of 40 sec EEG data. The other is computation for mapping. Interpolation is carried out by means of the two-variable sampling function so as to satisfy potentials at 5 x 5 grid points. The interpolated values are quantized to 11 levels, and finally, potential distributions over the surface of the head are printed out on line-printers of each frequency band separately as shown on topographic maps. The EEG map displays some kinds of EEG abnormalities, for example, diffuseness of delta activity, asymmetry of alpha fields and suppression pattern of sleep spindles in patients with brain tumor or cerebrovascular diseases.
