| Abstract: | We investigated neuronal impulse activity in the sensorimotor cortex after substantia innominata (SI) stimulation in cats during the execution of an instrumental conditioned response consisting of placement of a paw on a pedal coupled with alimentary reinforcement. Stimulation of the SI was initiated 1 or 3 sec prior to conditioned stimulation. Background activity of the neurons was inhibited during stimulation of the SI. Preliminary stimulation of the SI one second in advance caused an increase of reactions linked to a subsequent conditioned stimulus and a conditioned-response movement in 32% of the neurons; a 3-sec lead caused increases of such reactions in 33% of neurons. In some cells which originally did not react to the conditioned excitation, a clear reaction did manifest after stimulation. Moreover, stimulation of the SI with a 1-sec lead caused inhibition of impulse reactions in 6% of the cells; with a 3-sec lead, it caused inhibition of impulse reactions in 33% of the cells. The spread of latencies of conditioned-response actions decreased 2- to 3-fold in this case. We discuss the possibility that acetylcholine, which is released by the terminals of cholinergic neurons of the SI, has a facilitating influence on the impulse activity of neocortical neruons.Bogomolets Institute of Physiology, Ukrainian Academy of Sciences, Kiev. Translated from Neirofiziologiya, Vol. 24, No. 1, pp. 11–20, January–February, 1992. |
