Stimulation of Somatosensory Cortex Locked to Whisker Motions in a Mouse Model of Active Sensing

Joseph Schroeder¹, Vincent Mariano², Gregory Telian³, Jason Ritt4
¹Boston University, ²Boston University, ³Boston University, 4Boston University

Active sensing incorporates closed-loop behavioral selection of information during sensory acquisition. The rodent whisker tactile system provides an ideal platform for studying these processes. We examined coordinated head and whisker motions of unconstrained mice performing a tactile search for a randomly located reward, and found that the mice select from a diverse range of available active sensing strategies, based at least in part on the behavioral context of a whisker contact. In particular, mice selectively employed a strategy we term contact maintenance, where whisking is modulated to counteract head motion and sustain repeated contacts, but only when doing so is likely to be useful for obtaining reward. The context dependent selection of sensing strategies, along with the observation of whisker repositioning prior to head motion, suggests the possibility of higher level control, beyond simple reflexive mechanisms. In order to investigate the role played by primary somatosensory cortex (SI) in driving whisk by whisk changes in active sensing behavior, we developed methods to deliver optogenetic feedback to SI, time locked to active sensing motions (whisking) estimated through facial electromyography (EMG). We found that stimulation regularized whisking (increasing overall periodicity), and shifted whisking frequency. These behavioral changes emulate changes observed when rodents actively contact objects, suggesting a role for SI in action selection. Better understanding of a sensory cortex role in motor function could guise design of improved sensory neuroprostheses that exploit active sensing context.

Keywords: Active Touch, Closed-Loop, Sensorimotor

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