Change of activity in visual cortical units during electrocortical desynchronization in rabbits

Abstract

1. Most (90%) recorded neurons had background activity of a continuous type and were uniformly distributed in all layers of the cortex, while a minority (10%) discharged in groups of spikes and were located mainly in deep layers of the cortex. 2. Neurons with a predominantly continuous type of background activity, with firing rates of 5–17/sec, showed both excitatory and inhibitory types of response, in the proportion of 2:1 respectively, to desychronization of the ECoG. Neurons of the middle cortical layers responded mainly by excitation, and in the deep layers by inhibition. 3. Spread of ECoG desynchronization was not blocked by undercutting the area of cortex. The undercutting, however, selectively depressed both background and evoked activity of neurons in layers IV and V, producing a relative increase in activity of neurons in the upper layers. 4. Statistical characteristics of the relationship between responses of spike activity of simultaneously recorded neurons showed no significant change after the underoutting operation, indicating the importance of intracortical systems of relations for maintaining functional organization of cortical neurons in working groups.