Neurochemical mechanisms of the involvement of cortical sensorimotor neurons in alimentary and orientational behavior.

The object of these experiments was the study of the features of the neurochemical mechanisms of the involvement of individual neurons of the sensorimotor cortex of the rabbit brain the orienting reaction and the goal-oriented alimentary behavior elicited by stimulation of the "hunger center" of the lateral hypothalamus using electrical current of varying intensity. It is demonstrated that the neurotransmitters acetylcholine and norepinephrine, in approximately equal percentages, reorganize the reaction of neurons at the subthreshold as much as at the threshold level of stimulation. The microiontophoretic application to cortical sensorimotor neurons of the protein synthesis blocker, cycloheximide, also elicits alterations in their reactions to threshold and subthreshold stimulation of the lateral hypothalamus which are apparently linked to the suppression of synthesis of neuropeptides specific to both behaviors. It is proposed that the orienting, and especially the alimentary, motivational reactions are achieved by the activation of the synthesis of specific peptide molecules in the cortical sensorimotor neurons, which in fact may induce a change in their sensitivity to neurotransmitters.