Learning and Plasticity in Retro-Hippocampal Circuits

Dartmouth College, Hanover NH

Investigators

Abstract

The mammalian hippocampus is essential for binding together individual objects or events with the place and time in which they occur ('episodic memory'). An essential part of this process is the binding together of stimuli that compose the environment, or context. For example, a person recognizes his/her home in part because various individual sensory stimuli have been linked together as a "unit" that is identified collectively. These units of associated stimuli remain labile and can be updated as circumstances change. Thus, contextual learning/memory provides an organism with several adaptive advantages, including the ability to recognize and predict where a biologically significant stimulus may be located. Information regarding the physical and temporal context in which the object/event occurs is provided to the hippocampus by a network of specific cortical regions; yet, it is unknown how the components of this network contribute to processing contextual information. This project will illuminate the how the different regions that compose the where/when pathway contribute to contextual learning/memory. Addressing these issues will lead to the development of a new model of cortico-hippocampal function and provide essential information regarding the basic organizing principles of the mammalian hippocampal memory system. Sophisticated behavioral methods will be combined with innovative neurobiological techniques (recordings and designer receptor-based manipulations of cell populations in awake, behaving animals) to determine how the restrosplenial cortex (RSC) and the postrhinal cortex (POR) contribute to contextual learning and memory. Other studies will determine how the RSC and the POR interact at the synaptic level during learning. Carrying out the proposed studies will also provide valuable research training and opportunities for undergraduates at Dartmouth College, and use new initiatives to promote science education and research training, particularly in groups that are typically underrepresented in the sciences. At a community level, research findings will also be used to expose the local community to basic research in learning and memory through an outreach program developed in collaboration with a local science museum.