The features of the participation of the cholinergic mechanisms of the accumbens and caudate nuclei in the regulation of an instrumental defense reflex in dogs.

The influence of microinjections of carbacholine (0.1, 0.05, and 1.0 microgram) into the dorsal striatum (head of the caudate nucleus) and the ventral striatum (nucleus accumbens) on the motor components of the instrumental response and the criteria of execution of an instrumental task was studied in chronic experiments in eight dogs, based on a model of an instrumental defense reflex associated with the maintenance of a specific posture. The varied participation of the cholinoreactive structures of the caudate and accumbens nuclei in the regulation of the instrumental defense reflex was demonstrated in the dogs. Data were obtained indicating that the cholinoreactive system of the contralateral head of the caudate nucleus is structurally included in the regulation of the motor components of the instrumental response, of the main component of the reorganization of posture (the "disburdening" of the working extremity), and in the regulation of the tonic component of the voluntary movement and of its form. At the same time, the injection of carbacholine into the nucleus accumbens exerted, rather, a nonspecific activating influence on the motor systems. An improvement in attention to significant stimuli and the prolongation of the observed effects were also features of the activation of the cholinoreactive system of this nucleus. These changes took place in the case of both ipsi- and contralateral influences; this makes it possible to consider the inclusion mainly of sensory mechanisms in the realization of these influences.