Abstract
Relations of evoked potentials by photic stimulations to EEG patterns and ages were investigated in over a hundred persons selected at random. Responses of EEG evoked by stimulations were composed mainly of the three parts. The negative waves appeared in the first part (I) having a latency of 60 msec., and reappeared 100 msec. after stimulation in the second part (II). Then positive waves were observed in the third part (III) 150 msec. after the beginning. In this study, responses of EEG were classified in six patterns, from type A to type F. In type A, (I) was observed clearly, but (II) was not clearly, and (III) followed them. In type B, there were two peaks of (I) and (II) evidently. In type C, (I) was changed into positive waves and only (II) appeared distinctly. In type D, several negative undulations were added between (I) and (II), so (II) did not always appear distinctly. In type E, some negative undulations were only appeared. We distributed such EEG to type F that could not be classified into five patterns, type A to type E.
According to analysis of frequencies, basic EEG patterns were sorted into six groups. These were Delta-type, Theta-type, Theta Alpha-type, O-type and Beta-type. For example Delta-type means the EEG pattern whose delta waves show high ratio, O-type means that all types of waves show about equal ratio severally.
Photic stimulations were given with 0.5c/sec flash for 100 micro sec. Responses were re-corded through right occipital lead.
The following results were obtained: Type C was revealed mainly on Alpha-type, and hardly appeared on Delta, Theta and Alpha-type.
When basic waves included Delta-type and Theta-type, type D had a tendency to increase.
In the basic waves of children under 13 years old, Delta-type showed the highest ratio, and in these basic waves, type B were appeared more often than others.
