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). The bilateral application of 5 or 10 micrograms of Dopamine (DA) through chronically implanted cannulae in the CN significantly decreased the lever pressing in the non rewarding situation without changing the MCR. Injection of 5 micrograms of L-DOPA caused very small effects assessed during the following 10 min. However, 10 micrograms of L-DOPA produced a significant decrement of lever pressing (CS-off) in two out of four injections. These findings further support the postulation that catecholamines in the CN have a behavioral inhibitory action upon a motor conditioned response.
D000818:Animals; D002415:Cats; D002421:Caudate Nucleus; D003216:Conditioning, Operant / Q000187:drug effects; D004298:Dopamine / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D008297:Male; D008845:Microinjections; D009043:Motor Activity
D004298:Dopamine