The role of hippocampal NMDA receptors in encoding and consolidation of spatial information on the spatial version of the water task

Abstract

The NMDA receptor is a proposed molecular mechanism responsible for the structural changes that occur in neurons during learning and memory formation. I investigate the role that NMDA receptors have in hippocampal spatial learning and memory. Three projects were done, in which hippocampal NMDA receptors were pharmacologically blocked in groups of rats. They were pre-trained on a spatial version of the Morris water task with mass reversal training occurring in same or different training environments as pre-training. I measured expression of Arc protein throughout the main hippocampal subfields, CA1, CA3, and dentate gyrus, after training. I observed that NMDA receptor blockade allowed spatial learning but not consolidation when using previously acquired environmental information, and impaired learning when this information was novel. Arc protein expression in the dentate gyrus followed this pattern of NMDA receptor dependent spatial behavior. These results implicate dentate NMDA receptors in the acquisition of novel environmental information.