Effect of motor control on sensory coding in the awake, behaving mouse

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Our knowledge of the neural mechanisms of sensation comes mainly from a passive experimental paradigm where sensory stimuli are presented to the immobilised sense organ of an anaesthetised animal (e.g., spot of light projected on the retina). However, most species actively seek information by coordinating motor control of their sense organs (e.g., eyes, hands, whiskers) with sensory processing ('active sensing'). Indeed, the activity of sensory receptors can be strongly affected by sense organ movements: if eye movement is abolished, the visual image fades away. The concern that motor control might have an important impact on sensory coding was difficult to address fully in the past due to technical limitations.Analogously to the way that humans use motor control to explore objects by movement of our hands and eyes, rodents explore their environment by rhythmically sweeping their whiskers backwards and forwards ('whisking'). The whisker sense is extremely important to these animals: it dominates the brain's somatosensory areas. The whisker sense of rats/mice offers an excellent model system to get insight into the central question of this proposal - how sensory mechanisms depend on motor control. How the whiskers move and interact with objects can now be precisely measured using high-speed video cameras. Moreover, since engineers have long been interested in how rod-like objects bend, there is a well-developed mathematical theory that can be used to estimate the mechanical forces of whisker-object interaction from video data.The way that we perceive the world is fundamentally constrained by primary sensory neurons, which translate signals in the environment (such as bending of a whisker) into corresponding patterns of action potentials. Here, we propose to determine the tactile features that primary whisker neurons encode as a mouse actively explores objects with its whiskers. The significance of the work is that it will provide insight into the general question of how motor control (here, whisking) and sensory processing interact to constrain how we perceive the world.