THE EFFECTS OF BILATERAL STRIATAL LESIONS ON THE ACQUISITION OF AN OPERANT TEST OF SHORT-TERM-MEMORY

IT has been previously shown that lesions of the dorsal striatum can d isrupt performance on a variety of cognitive tasks related to frontal cortex function. In order to extend these studies, we have investigate d the effects of bilateral striatal lesions on the acquisition of an o perant test of short term memory in the delayed nonmatching to positio n paradigm. The animals received either ibotenic acid or saline contro l injections into the dorsal striatum prior to training on the non-mat ching task. Striatal lesions retarded acquisition of the task, althoug h with further training the lesioned rats achieved a similar level of asymptotic performance to the control animals. The lesioned rats also exhibited marked nocturnal locomotor hyperactivity when tested under c onditions of food deprivation, but not when tested satiated. The resul ts indicate that bilateral striatal lesions induce mild deficits in th e acquisition of the discrimination rules involved in performance of t he delayed nonmatching to position task. The present study does not su pport a role for the neostriatum in the specific mediation of short te rm memory in an operant DNMTP test.