Consolidation of cellular memory representations in superficial neocortex

A map of spatial navigation for neuroscience

“…In a more radical take, systems consolidation theory claims that all memories (including episodic and spatial memories) are eventually copied over to the cortex and become independent of the hippocampus (Squire et al, 1984, Maguire and Mullally, 2013, Barry and Maguire, 2019. This latter view could be consistent with findings of spatially tuned cells throughout the cortex reviewed earlier, whose establishment, nonetheless, depends on the hippocampus (Esteves et al, 2021(Esteves et al, , 2023. Eleanor Maguire and colleagues favor this view and claim that the hippocampus continues to be involved in spatial navigation not because of its role in storing spatial memories, but because it supports the construction of spatially coherent scene representations in real time based either on perception, consolidated neocortical memories, or even imagination (Maguire and Mullally, 2013, Barry and Maguire, 2019, Hassabis et al, 2007.…”

“…In fact, one study reported spatially selective cells in all neocortical areas examined (Esteves et al, 2021). These cells partly depended on an intact hippocampus to develop their spatial selectivity, but could sustain it in familiar environments in the absence of a hippocampus (Esteves et al, 2023). Furthermore, fMRI studies in humans have also found signatures of grid cells in a range of areas outside the hippocampal formation including posterior and medial parietal, cingulate and medial prefrontal areas (Doeller et al, 2010, Jacobs et al, 2013.…”

Pattern Completion and Rate Remapping in Retrosplenial Cortex

“…To understand this, inactivation experiments and simultaneous recording across CA1, RSC and other regions are needed. Hippocampal lesion experiments have shown that, post-lesion, RSC place elds do not form as well in novel environments, but familiar environments retain PCCs after the lesion 23 . This is consistent with behavioral experiments that show that over time, memories that initially depend on hippocampus are consolidated into hippocampus-independent form in neocortex [57][58][59] .…”

“…They are also driven by cues similar to those that drive hippocampal place cells [19][20][21] and depend on an intact hippocampus to form 14,22 . Once established, however, RSC position-correlated responses survive hippocampal lesions 23 .…”