Afferent and efferent mechanisms of the intensification of neostriatal cholinergic activity.

Data have been obtained in chronic experiments on 34 dogs, based on an instrumental defense reflex model associated with the maintenance of a specific posture, which suggest that activation of the cholinergic system of the neostriatum leads to a large number of changes in both the sensory and the motor spheres. The influences on motor behavior, observed mainly through effects on the cholinergic system of the contralateral caudate nucleus, reside in the intensification of the tonic constituent of movement, in inhibition of the phasic component of movement, and restriction of locomotor activity, all the way up to complete shutdown. The influences on sensory mechanisms, observed both through ipsi- and contralateral effects on the cholinergic system of the neostriatum, reside in an improvement of the differentiation of significant signals and are evidently through inhibition of the nonspecific afferent stream. Data are presented on the important role of the cholinoreactive systems of the CM-Pf complex of the thalamus in the intensification of the cholinergic activity of the neostriatum.