Response-reinforcer associations after caudate-putamen lesions in the rat: spatial discrimination and overshadowing-potentiation effects in instrumental learning.
Experiment 1 demonstrated that rats with caudate-putamen lesions show an impairment in the acquisition and reversal of a spatial maze task when compared with unoperated control subjects. Experiment 2 examined lever-press responding supported by a variable interval schedule in three groups of subjects: a group with caudate-putamen lesions, a group with lesions of the posterior cortex, and an unoperated control group. The presentation of a 0.5-s, response-contingent light correlated with reinforcement generated an elevated response rate in the two operated groups but tended to suppress responding in the control group, perhaps by overshadowing the response-reinforcer relation. Only the group with cortical lesions maintained the elevated rate when the light was uncorrelated with food delivery. Experiment 3 confirmed for these same subjects that caudate-putamen lesions produce a spatial learning deficit. No deficit was seen in the posterior cortex group. It is suggested that caudate-putamen lesions disrupt the mechanism underlying the response-reinforcer association upon which spatial maze learning and free operant responding in part depend.
D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology; D001931:Brain Mapping; D002421:Caudate Nucleus / Q000502:physiology*; D003216:Conditioning, Operant / Q000502:physiology*; D003463:Cues; D004193:Discrimination Learning / Q000502:physiology*; D008297:Male; D011939:Mental Recall / Q000502:physiology; D009949:Orientation / Q000502:physiology*; D011699:Putamen / Q000502:physiology*; D051381:Rats; D012193:Reversal Learning / Q000502:physiology