Interactions between visual and non-visual signals in the head direction system

We propose a collaborative M2 internship project at the INCC (CNRS, Université Paris Cité, 45 rue des Saints-Pères, Paris, France) under the co-supervision of Desdemona Fricker and Mark Wexler. The candidate will be involved in an innovative project dedicated to studying the neural basis of orientation in space by recording from head-direction (HD) circuits in moving or stationary mice. The project will investigate the interaction between visual and non-visual signals in the HD system. Orientation in space is a fundamental cognitive process based on the head direction (HD) system, that functions as the brain’s compass. HD signals are generated from vestibular inputs, are stabilized through visual cues and are internally organized to maintain directional activity. How specific brain areas produce the stability of HD signals and their rapid resetting to visual landmarks is poorly understood from a neurophysiological point of view. This project aims to understand the dynamical structure of the spatial orientation network of neurons in awake mice that either undergo real rotations, or experience visual stimuli that simulate rotations. We focus the key structures involved in head directional signaling, anterior thalamus, retrosplenial cortex and presubiculum, and also the visual cortex. Neuronal activity will be recorded using high-density silicon probes (Neuropixels) that can be positioned across two of these structures simultaneously. Visual stimuli are projected in a matched or mismatched fashion with respect to rotational movements. The hypothesis is that vestibular information, visual landmark input and optic flow interact in populations of neurons with mixed selectivities. We will use both univariate and multivariate techniques to characterize the information about rotation coded in different brain regions. We propose to record and manipulate populations of HD neurons and interneurons, to achieve a better understanding of neural correlates of spatial coding and visual perception. The candidate will be involved in both the recording and analysis of neural data. He or she will use state-of-the-art high density extracellular electrical recording techniques, and will be involved in running the animal experiments which includes animal habituation and recording sessions with Neuropixels probes in awake mice. Another important aspect of the project is also data analysis of HD cell activities. A background in engineering, math and/or programming will be a plus.