How does our brain tell us where we are based on what we see and hear? - Neuronal basis of cross-modal sensory integration for navigation

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Several spatial cells have been discovered, including place cells in the hippocampus and gridcells in the medial entorhinal cortex. The activity of these cells provides an animal with aninternal representation of space as it explores an environment. However, a key unsolvedproblem is how spatial cells integrate multiple sensory inputs (such as visual, auditory,olfactory, etc) in order to form spatial representations.Virtual reality (VR) offers a powerful tool for investigating spatial cognition, allowingenvironmental manipulations that are impossible in the real world. We have recentlydeveloped a two-dimensional VR (2D VR) system for mice with mainly visual andmotor/proprioceptive inputs, allowing a close approximation of spatial representation in thereal world.The goal of this project is to study the integration of sensory inputs across modalities duringspatial navigation. In particular we aim to 1) Develop a new 2D VR, where both visual andauditory cues can be individually controlled and manipulated, and train animals to navigatein this multisensory VR. 2) Characterise activity of spatial cells in this multisensory VR, inparticular the topography of these spatial cells with respect to their response to sensoryinputs. 3) Examine how these spatial cells interact in order to integrate visual and auditoryinputs, forming a unified spatial representation. The primary techniques that will be usedinclude in vivo electrophysiological single-unit recording using tetrodes and Neuropixelprobes, as well as in vivo 2-photon imaging. Theoretical models will be constructed based onthe experimental results, which will be used to explain experimental outcomes and makefurther predictions and hypotheses for future directions.Experiments will be supervised mainly by the primary supervisor, while the modelling will beguided primarily by the secondary supervisor. Work will be carried out in both QMUL and UCL.