Sites of Neocortical Reorganization Critical for Remote Spatial Memory

TLDR

The hippocampus is essential for forming spatial memories but does not retain them long term. Using functional imaging and targeted neuronal inactivation in mice, the study mapped remote spatial memory storage and retrieval to prefrontal, anterior cingulate, parietal, and retrosplenial cortices. The study found that remote spatial memories are stored and retrieved in these cortical regions, with long‑term retention accompanied by synaptogenesis and laminar reorganization and a progressive disengagement of the hippocampus, allowing cortical networks to mediate recall independently.

Abstract

The hippocampus is crucial for spatial memory formation, yet it does not store long-lasting memories. By combining functional brain imaging and region-specific neuronal inactivation in mice, we identified prefrontal and anterior cingulate cortices as critical for storage and retrieval of remote spatial memories [correction]. Imaging of activity-dependent genes also revealed an involvement of parietal and retrosplenial cortices during consolidation of remote memory. Long-term memory storage within some of these neocortical regions was accompanied by structural changes including synaptogenesis and laminar reorganization, concomitant with a functional disengagement of the hippocampus and posterior cingulate cortex [correction]. Thus, consolidation of spatial memory requires a time-dependent hippocampal-cortical dialogue, ultimately enabling widespread cortical networks to mediate effortful recall and use of cortically stored remote memories independently.