Sex differences in visual evoked potential and electroencephalogram of healthy adults.

Sex differences in flash visual evoked potentials (VEPs) and electroencephalograms (EEGs) were studied in 200 healthy adults (100 females and 100 males). Following results were obtained. (1) Waveforms of Group Mean VEPs of each sex had roughly triphasic contour, consisted of components P1 approximately N8, within 500 msec of latency. (2) Latencies of VEP components by t-test, (3) By analysis of covariance, sex differences in peak-to-peak amplitudes were still significant after eliminating effects of body height, body weight or age, but not those in latencies after eliminating the effect of body height. (4) Quantitative analysis of EEGs resulted in significantly smaller absolute amplitudes, and significantly larger theta, larger beta 1 and smaller alpha 2 power % in females. (5) Peak-to-peak amplitudes of later components in VEPs for 5CH (O1-->Cz) were significantly and positively correlated with EEG absolute amplitudes within each sex group. (6) There were few significant differences in VEP components between follicular phase and luteal phase in females. The sex differences in VEPs verified in this study may be attributed to genetically determined sex differences in neuroendocrinological systems.