Whisker kinematics in the cerebellum

Abstract

The whisker system is widely used as a model system for understanding sensorimotor integration. Purkinje cells in the crus regions of the cerebellum have been reported to linearly encode whisker midpoint, but it is unknown whether the paramedian and simplex lobules as well as their target neurons in the cerebellar nuclei also encode whisker kinematics and if so which ones. Elucidating how these kinematics are represented throughout the cerebellar hemisphere is essential for understanding how the cerebellum coordinates multiple sensorimotor modalities. Exploring the cerebellar hemisphere of mice using optogenetic stimulation, we found that whisker movements can be elicited by stimulation of Purkinje cells in not only crus1 and crus2, but also in the paramedian lobule and lobule simplex; activation of cells in the medial paramedian lobule had on average the shortest latency, whereas that of cells in lobule simplex elicited similar kinematics as those in crus1 and crus2. During spontaneous whisking behaviour, simple spike activity correlated in general better with velocity than position of the whiskers, but it varied between protraction and retraction as well as per lobule. The cerebellar nuclei neurons targeted by the Purkinje cells showed similar activity patterns characterized by a wide variety of kinematic signals, yet with a dominance for velocity. Taken together, our data indicate that whisker movements are much more prominently and diversely represented in the cerebellar cortex and nuclei than assumed, highlighting the rich repertoire of cerebellar control in the kinematics of movements that can be engaged during coordination. imageKey points Excitation of Purkinje cells throughout the cerebellar hemispheres induces whisker movement, with the shortest latency and longest duration within the paramedian lobe. Purkinje cells have differential encoding for the fast and slow components of whisking. Purkinje cells encode not only the position but also the velocity of whiskers. Purkinje cells with high sensitivity for whisker velocity are preferentially located in the medial part of lobule simplex, crus1 and lateral paramedian. In the downstream cerebellar nuclei, neurons with high sensitivity for whisker velocity are located at the intersection between the medial and interposed nucleus.

GlyT2-positive interneurons regulate timing and variability of information transfer in a cerebellar-behavioural loop

“…In all cases, bouts of whisking activity were associated with pronounced alterations in cerebellar spiking activity (Figure 1b, c). Single cell recordings previously revealed widespread tuning to whisker position in granule cells, inhibitory interneurons and Purkinje cells (Bosman et al, 2010;Brown & Raman, 2018;Chen et al, 2016Chen et al, , 2017Zhai et al, 2024). We therefore measured tuning to whisker position amongst single units of our population recordings.…”

“…Here we investigate the influence of Golgi cell activity on cerebellar population activity in the context of whisker movement, to reveal how inhibitory feedback influences sensorimotor transformations and ongoing behaviour. Neuronal representations of whisking activity in the lateral cerebellum are widespread (Bosman et al, 2010;Brown & Raman, 2018;Chen et al, 2016Chen et al, , 2017Zhai et al, 2024), and are partly based on a linear rate code, whereby the firing rates of cerebellar neurons predict upcoming whisker position (Chen et al, 2016). These representations are first seen in patterns of mossy fibre input and are passed forward at each stage of cerebellar cortical processing (Chen et al, 2017).…”