Investigating spatial coding resolution in the CA3 area of the hippocampus in mice navigating a virtual reality environment

Each place in an environment is represented by the activity of an ensemble of hippocampal place cells, among a larger population of silent neurons. This representation can be more or less accurate depending on the size of the ensemble (a larger proportion of place cells being associated with a higher spatial coding resolution, like the number of pixels in an image), the size of their place field (the surface of the environment where they discharge corresponding to the size of the pixels) but also the spatial and temporal stability of their discharge. The factors that control spatial coding resolution are poorly understood. To address this question we take advantage of recently developed virtual reality systems for rodents combined with high-density extracellular recordings (silicon probes). Virtual reality allows a fine control of the sensory cues that animals can use to locate themselves. Our recent results in the CA1 region of the hippocampus (Bourboulou, Marti et al., 2019 see attachment) show that hippocampal spatial coding resolution can be locally modulated within the same environment. In this project we would like to determine if this modulation could be inherited from the CA3 region.

The student will:

– Train mice to navigate in virtual environments more or less enriched with local visual cues
– Record the activity (action potentials and local field potentials) in the CA3 region of the hippocampus during navigation in the virtual environment
– Make brain sections to determine the location of electrodes post-hoc
– Participate in the analysis/interpretation of the results obtained

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