Coding of Space and Memory in the Hippocampus


Space is the most conspicuous functional correlate of rodent hippocampal neurons. A prominent theory posits that hippocampal “place cells” constitute a spatial framework, and that items and events of experience are organized within this spatial framework to create a “cognitive map”. Cortical inputs to the hippocampus are channelled through the lateral entorhinal cortex (LEC) and the medial entorhinal cortex (MEC). While MEC encodes pathintegration-derived spatial information, we recently showed that LEC encodes sensory-derived spatial as well as nonspatial information. Such sensory-derived information is critical to the cognitive map, for anchoring the spatial representation to the real world using landmarks, and for storing and processing nonspatial information in the context of spatial information. Our primary research interest is to understand how the hippocampal network creates a coherent representation of events within their spatial context. Unravelling the interplay of sensory-derived spatial and nonspatial information brought in by LEC and the internally generated, path-integrationbased spatial representation in MEC is a crucial step in this endeavour. We hypothesize that gating of sensory information by LEC plays a role in the creation and maintenance of the representation of space in the hippocampal system. Selecting relevant sensory information may be the vital contribution of LEC to cognitive map formation and function. We record activity of neurons in awake, behaving rats to test whether LEC gates sensory information for task relevance, and measure the effect of such gating on the activity of MEC and the hippocampus. Answers to these fundamental questions will help decipher how the cognitive map is created and used during
memory formation.

PI : Sachin Deshmukh (Webpage)