Han Yin Cheng, Dorothy WU Overington, Kate J Jeffery. Three separable roles for context in breaking environmental symmetries for place cells. bioRxiv 2023.05.28.542182; doi: https://doi.org/10.1101/2023.05.28.542182

Abstract
“We investigated how place cells resolve spatial ambiguities, such as identical compartments and rotational symmetry, by recording from hippocampal CA1 in rats exploring a visually ambiguous environment, the “2 box”, comprising two identical, connected rectangular compartments with directionally opposing layouts. The layouts distinguish the two ends of each box, while the boxes themselves are distinguished by their odor context. We found that firing field ensembles were usually oriented consistently relative to the odor cues, indicating use of odor context to break the overall global symmetry. Some place cells also maintained a consistent context-specific relationship to the layout cues, thus “remapping” between boxes. Other place cells ignored both the context and the layout cues but maintained the same relationship to walls of given orientations, thus repeating their fields in the two boxes. No cells ignored orientation altogether by rotating independently of the ensemble. And finally, sometimes the whole ensemble rotated its firing en bloc, decoupling from the odor context cues. To explain these observations we propose that odor establishes a context signal having three simultaneous but separable roles, to: (i) orient the global directional signal via an association with layout cues, (ii) gate the spatial inputs onto place cells, and (iii) organize the configural association of head direction with layout. This configuration can in turn regenerate the context signal if the original sensory input becomes unavailable, explaining how spatial firing patterns originally established by the odor context can become independent of it. We speculate that these interactions occur in retrosplenial cortex.”

Han Yin Cheng, Dorothy WU Overington, Kate J Jeffery. Three separable roles for context in breaking environmental symmetries for place cells. bioRxiv 2023.05.28.542182; doi: https://doi.org/10.1101/2023.05.28.542182