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.

Transversal functional connectivity and scene-specific processing in the human entorhinal-hippocampal circuitry

“…Convergence of scene and object information is compatible with recent rodent work that shows joint coding of scene and object information (notably operationalized as spatial and non-spatial information, respectively) along CA1 and within the lateral EC ( Deshmukh, 2014 ; Doan et al, 2019 ; Vandrey et al, 2021 ; Wilson et al, 2013 ; Yeung et al, 2019 ). Note that a supplemental analysis of information processing in the cortical source regions showed indeed, specific object processing in perirhinal source regions (see appendix 5).…”

Functional connectivity and information pathways in the human entorhinal-hippocampal circuitry

“…Convergence of item and contextual information is compatible with recent rodent work that shows joined coding of spatial (location) and non-spatial (object) information along CA1 and within the lateral EC (Deshmukh, 2014;Doan et al, 2019;Vandrey et al, 2021;Wilson et al, 2013;Yeung et al, 2019). However, we cannot confirm reports about higher functional activity for object than scene processing within these areas in the human brain Navarro Schröder et al, 2015;Berron et al, 2018;also indicated in Dalton et al, 2018 andSchultz et al, 2012).…”

Grid and Nongrid Cells in Medial Entorhinal Cortex Represent Spatial Location and Environmental Features with Complementary Coding Schemes

“…Furthermore, we show that integration of feature and spatial coding occurs within mEC and that mEC cells can serve as a source for the emergence of feature coding by the hippocampus, in addition to direct inputs from lEC (Deshmukh, 2014; Knierim et al, 2006; Renno-Costa et al, 2010). LEC lesions were found to produce a 30 % impairment in hippocampal rate coding (Lu et al, 2013), which indicates that remaining entorhinal inputs may provide a major contribution to rate coding.…”