The anatomy and function of the postrhinal cortex.

Abstract

The parahippocampal cortex (PHC) in the primate brain is implicated in the medial temporal lobe (MTL) memory network for spatial and episodic memory, but the precise function of this region remains unclear. Importantly, the rodent postrhinal cortex (POR) provides a structural and connectional homolog to the primate PHC. This homology permits the use of the powerful tools available in rodent models to better understand the function of the PHC in the human and nonhuman primate brains. Although many articles have compared and dissociated the function of the rodent POR from other areas in the MTL implicated in learning, memory, and memory-guided behavior, there are no in-depth reviews, particularly covering the last two decades of research. Nor has there been a review of the literature on the potential role of the POR in attention. Here, we review the anatomical and functional connectivity of the POR in rats, examine the evidence for proposed behavioral functions of this region, and suggest a model that accounts for the array of observations. We propose that the rodent POR binds nonspatial information and spatial information to represent the current local physical environment or context, including the geometry of the space and the spatial layout of objects and features in the environment. The POR also automatically monitors the environment for changes and updates representations when changes occur. These representations of context are available to be used by multiple brain regions, including prefrontal, posterior cortical, and hippocampal areas, for context-guided behavior, associative learning, and episodic memory.

Hippocampal lesions impair non‐navigational spatial memory in macaques

“…Cases MO and MI both had damage that extended to a portion of the posterior parahippocampal cortex, and these animals displayed deficits that were more severe than average. This is consistent with the critical role for the parahippocampal cortex as a route for spatial information to reach the hippocampus (Aggleton, 2012;Estela-Pro & Burwell, 2022), and our prior study on PHC (LaFlamme et al, 2020).…”

Direct cortical inputs to hippocampal area CA1 transmit complementary signals for goal-directed navigation

“…More updated reviews of function and anatomy have called for a reappraisal of this distinction pointing to mixing of these streams at multiple levels [19,17,20]. Understanding the role that EC plays in refining, gating, or transforming sensory information is fundamental to understanding how and why place cells form, as well as the mechanisms underlying neuronal navigation and memory systems.…”

Neurons in the postrhinal cortex encode nonspatial context during visual biconditional discrimination

“…We have proposed that the POR represents environmental contexts including the spatial layout of objects and patterns, that the POR automatically monitors the current context for changes and updates context representations when changes occur, and that object and pattern information arrives to the POR directly from the PER (Estela-Pro and Burwell, 2022, Furtak et al, 2012, Ho and Burwell, 2014, Peng and Burwell, 2021, Burwell and Hafeman, 2003). Such representations are available to multiple brain regions, for example, the hippocampus for associative learning (Agster and Burwell, 2013) and prefrontal cortex for context guided behavior and cognition (Hwang et al, 2018).…”

“…We have suggested that the PER provides object and pattern information to the hippocampus for associative learning and episodic memory and to the POR for representing the local physical context (Heimer-McGinn et al, 2017). Such information could be used to represent the local physical context (Estela-Pro and Burwell, 2022, Ho and Burwell, 2014, Peng and Burwell, 2021). POR representations of context are available to other brain regions for context-guided behavior and cognition, for example, the prefrontal cortex (Hwang et al, 2018).…”