The cerebellum linearly encodes whisker position during voluntary movement.

Susu Chen,George J Augustine,Paul Chadderton

doi:10.7554/elife.10509

Abstract

Active whisking is an important model sensorimotor behavior, but the function of the cerebellum in the rodent whisker system is unknown. We have made patch clamp recordings from Purkinje cells in vivo to identify whether cerebellar output encodes kinematic features of whisking including the phase and set point. We show that Purkinje cell spiking activity changes strongly during whisking bouts. On average, the changes in simple spike rate coincide with or slightly precede movement, indicating that the synaptic drive responsible for these changes is predominantly of efferent (motor) rather than re-afferent (sensory) origin. Remarkably, on-going changes in simple spike rate provide an accurate linear read-out of whisker set point. Thus, despite receiving several hundred thousand discrete synaptic inputs across a non-linear dendritic tree, Purkinje cells integrate parallel fiber input to generate precise information about whisking kinematics through linear changes in firing rate.

Highlights

Tactile sensation is an active process whereby sensory information is acquired through self-initiated movement
Tactile whisker stimulation can change the rate of both SS and complex spikes (CS) (Bower and Woolston, 1983; Loewenstein et al, 2005; Bosman et al, 2010), it is not known whether free whisking affects Purkinje cells (PCs) activity
Whisker movement was associated with an overall enhancement of the activity of PCs (Figure 1F, G), the direction and amplitude of SS rate change during whisking was not related to baseline SS firing rates (r = 0.06, p=0.69, n = 47)

Summary

Introduction

Tactile sensation is an active process whereby sensory information is acquired through self-initiated movement. The rodent whisker system provides an attractive model to tackle questions related to active sensory processing (O’Connor et al, 2002; Crochet et al, 2011) and sensorimotor integration (Kleinfeld et al, 2006). Amongst multiple processing regions in the brain, the cerebellar cortex is a major site of sensorimotor integration, but little is known about its role in active whisking. Growing evidence suggests synchronization of activity between the cerebellum and other whisker-related brain regions both under anesthesia and during active whisking in the awake state

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Discussion

Conclusion