Probabilistic Perceptual Decisions during Navigation Are Driven by a Small Subpopulation of Neurons in a Single Cortical Column of the Primary Somatosensory Cortex.

Perceptually driven behavioral choices are thought to develop gradually from sensation to perception in the somatosensory cortex to guide decision-making in higher-order cortical areas. The primary somatosensory cortex (wS1) of rodents related to their mystacial whiskers has been a model system to study this information flow. However, the role of wS1 in this process is often debated based on controversial results of loss-of-function behavioral experiments that often require prolonged training and movement restraints. Here, to elucidate the role of wS1 in decision-making, we developed an ethological whisker-guided virtual reality (VR) paradigm that closely mimics natural navigation in underground burrows. Untrained mice of either sex navigate left and right turns at high speed by sensing VR walls with just a pair of their C2 whiskers. Inactivating layer 4 of C2 barrel results in a loss of the ability to produce turns contralateral to the lesion. Using a probabilistic model of collision avoidance in the presence of noise and uncertainties, we hypothesize that wS1 is involved in a feedback control loop that requires continuous updates and predictions to infer the optimal path for collision avoidance.