HIPPOCAMPAL SYNAPTIC PLASTICITY DURING INSTRUMENTAL LEARNING

The present research examined the role of hippocampal NMDA-dependent s ynaptic potentiation on appetitive instrumental conditioning under a c ontinuous reinforcement schedule. In the first experiment, low (.025 m g.kg) or moderate (.05 mg/kg) dosages of the NMDA receptor antagonist, MK801, failed to increase the number of training days required to rea ch acquisition criterion; number of training days required to reach cr iterion for extinction were also unaffected. In the second experiment, a higher dosage (.10 mg/kg) of MK801 or induction of long-term potent iation failed to alter the, number of responses occurring during acqui sition. These data suggest that hippocampal synaptic potentiation does not play a prominent role in instrumental learning with simple contin gency conditions. It is suggested that hippocampal LTP reflects a perc eptual process that contributes differentially to spatial cognition, c lassical and instrumental conditioning.