Participation of the nigro-striatal and mesolimbic dopaminergic systems of the brain in the control of components of learned motor responses in dogs.

We studied the role of the striatal and limbic dopaminergic systems in the regulation of instrumentally conditioned avoidance behavior and postural adjustment in chronic experiments on dogs. Dopamine in doses of 3 micrograms was introduced bilaterally into the caudate nucleus head and the nucleus accumbens of the forebrain through implanted cannuli. Predominantly unidirectional effects were demonstrated, but a clear acceleration of the initiations of both conditioned-reflex postural adjustment and voluntary movement were obtained from the caudate nucleus; there was a marked degree of expressiveness to this movement. The greatest effects were obtained during simultaneous, bilateral introduction of dopamine into both structures in dogs with an akinetic form of motor pathology. We conclude that the integration of the striatal and limbic dopaminergic systems is of critical necessity for the initiation and regulation of the components of voluntary movement.