Effect of stimulation of cortical association areas in rabbits on evoked potentials and unitary responses in the visual cortex.

Abstract

1. The cortical association areas exert an important influence on EP and single unit activity in the visual cortical projection area. 2. Stimulation of the anterior cortical association areas leads to lengthening of the inhibitory pause and to a decrease in the late discharges in the response of visual projection neurons to flashes, and this is reflected in a significant reduction of the secondary negative-positive complex of the EP. It can be postulated on the basis of these data that the anterior association cortex has an inhibitory influence on the principal neurons of the visual cortex receiving the afferent signal. 3. Stimulation of the posterior association cortex causes lengthening and deepening of the inhibitory pause in unit activity and an increase in the late discharges in the response of visual cortical neurons to flashes; there is a corresponding enlargement of the secondary negative-positive complex of the EP. On the basis of these results it is postulated that the posterior association cortex has a facilitatory influence on the recurrent inhibition system in the visual cortex.