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bioRxiv · 10.1101/2023.05.15.540888

On the results of causal optogenetic engram manipulations

Jou, C.·Hurtado, J. R.·Carrillo-Segura, S.·PARK, E. H.·Fenton, A. A.
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Abstract

Hippocampal neurons encoding memories discharge in sparsely-distributed patterns; they can be optogenetically tagged, then photostimulated to elicit conditioned behavior, potentially generating a synthetic memory trace, "engram". We investigated mouse hippocampal population responses to the photostimulation of memory-tagged neurons to determine if memory-associated discharge is mimicked in hippocampus, a network with non-linear and homeostatic interactions. Both memory-tagged and not-tagged CA1 cells adjusted firing during photostimulation without altering place cell firing fields. Cell-pair cofiring relationships also maintain during photostimulation, indicating a low-dimensional, dynamical structure-preserving, homeostatic network response instead of the photostimulated pattern. Photostimulating neurons that were tagged during place-avoidance memory elicits similar place-avoidance memory in control conditions. Thus artificial photostimulation elicits natural, stored, homeostatic neuronal network cofiring patterns to elicit memory, establishing mimicry evidence for the engram.

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Jou, C., Hurtado, J. R., Carrillo-Segura, S., PARK, E. H., Fenton, A. A.. 2023-05-17. On the results of causal optogenetic engram manipulations. https://doi.org/10.1101/2023.05.15.540888

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