Spatial and Nonspatial Representations in the Lateral Entorhinal Cortex

Abstract

The hippocampus is thought to function as a “cognitive map,” which stores nonspatial information such as items and events in a spatial framework. In order to understand the computations involved in creating such conjunctive nonspatial + spatial representations, it is essential to understand the function of hippocampal inputs. Medial entorhinal cortex (MEC) is known to convey spatial information to the hippocampus. In this chapter, we discuss recent evidence showing that lateral entorhinal cortex (LEC) conveys both spatial and nonspatial information to the hippocampus, in the presence of objects. Perirhinal cortex (PRC), a major cortical input to LEC, encodes nonspatial, object-related information, but does not encode spatial information in the presence of objects. Thus, the landmark-derived spatial information arises de novo in LEC. The classical dual-pathway model, in which LEC encodes nonspatial information while MEC encodes spatial information, cannot account for LEC spatial representation in the presence of objects. We propose that the functional difference between LEC and MEC is better understood in terms of the different inputs they use to create their representations: LEC generates spatial as well as nonspatial representations by processing external sensory inputs in contrast to MEC, which generates spatial representations by processing internally based path integration information.