Instrumental behavior in the activation or blockade of the neostriatum muscarinic receptors

In four dogs, microinjections of carbacholine enhanced the tonic component and inhibited the physical component of the instrumental defence reflex, put in order the posture, and increased its components' amplitude. Microinjections of raclopride yielded a similar though a less obvious result. Differentiation stimuli provided the greatest effect of both substances. A sharp improvement occurred in differentiation of sound signals. Microinjections of pyrenzepine yielded an opposite result. The data obtained are explained proceeding from the idea of a presence of the neostriatum's two efferent outputs exerting opposite effects on their targets, and the role of muscarine and dopamine receptors in their triggering and blockade.