THE ELECTROENCEPHALOGRAM AND PSYCHOPHYSIOLOGICAL REGULATION IN THE BRAIN

The paradoxical association of relatively large amplitude alpha 10± per second activity with a relatively low level of waking cerebral function is attributed to the inhibitory effects of subcortical 10 ± per second pacing of activity in the cortex and to associated autonomic effects causing cerebral constriction. On the other hand the association of fast activity with cortical excitation, metabolite (CO₂) production, and fast activity in cholinergic nerves accounts for associated vasodilatation. Thus, by the opposed effects of fast vs. 10 ± per second slower activity, cortical and subcortical mechanisms may regulate one another. This may provide a homeostatic mechanism by which excitation in the cortex is normally prevented from producing excessive discharge or from self-perpetuation. Underactivity, overactivity, or imbalance of these functions would account for the EEG and autonomic patterns seen in many abnormal mental conditions.