A physiologically inspired model for global remapping in the hippocampus
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KeywordsGrid Cell Entorhinal Cortex Cell Output Synaptic Weight Place Cell
The hippocampus is a brain structure that is involved in the formation and recall of episodic memories, including space-related behavior. Place-specific hippocampal activity patterns change dramatically if the animal is exposed to the same maze in different lab environments (global remapping) . Global remapping leads to decorrelated activity patterns, which is essential for many models of associative memory: it sustains flexibility and allows many patterns to be stored.
During hippocampal remapping the spatial activity pattern of grid cells undergoes locally coherent rotations and translations , but it is not known whether this coherence extends over different spatial modules, which are anatomically separated within the entorhinal cortex . Within a computational approach, we studied the influence of the incoherent realignment of different independent modules on the formation of place cell firing patterns in the hippocampus. We find that global remapping can indeed be caused by realigning a realistic number of modules, given the experimental constraints.
The grid layer thus provides a low dimensional parameterization of the different place maps without any synaptic plasticity in the projections, thereby indexing spatial memories. This result suggests that different independent modules are present in the entorhinal cortex and that their grid fields co-realign during global remapping.
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