Caudate unit activity and somal diameters in intact and nigral lesioned cats.

In a search for morphofunctional relationships in the head of the caudate nucleus (CN), we recorded extracellular unit activity in intact cats and in cats that had received bilateral injections of 6-OHDA into the substantia nigra (SN) 30 days previously. Only units firing spontaneously and continuously for 2 min were studied. In dorsal regions, potentials were small and iterative at almost constant intervals; the somal diameters were relatively small.

Facilitation of conditioned motor suppression by microinjections of dopamine in the caudate nucleus of cats.

The effects of Caudate Nucleus (CN) injections of catecholamines on the suppression of a motor conditioned response (MCR), lever pressing, was investigated. Cats were trained to press a lever to obtain 0.5 ml of milk when a conditioned discriminative stimulus was on (CS-on-reward on, MCR) and to suppress the response when the light was off (CS-off-reward off, suppression of motor conditioned response, SMCR).