Abstract
It is hypothesized that the cerebellum implements a forward internal model that transforms motor commands into predictions about upcoming movements. The predictions are compared with sensory feedback to generate sensory prediction errors critical to controlling movements. The simple spike firing of cerebellar Purkinje cells both lead and lag movement consistent with representations of motor predictions and sensory feedback. This study tests whether this leading and lagging modulation provides the prediction and sensory feedback necessary to compute sensory prediction errors. Two manipulations of the visual feedback are used in rhesus monkeys performing pseudo-random tracking. Consistent with a forward model, delaying the visual feedback demonstrates that the leading simple spike modulation with position error is time-locked to the hand movement. Reducing the feedback shows that the lagged modulation is directly driven by visual inputs. Therefore, Purkinje cell discharge carries both the motor predictions and sensory feedback required of a forward internal model.
Highlights
It is hypothesized that the cerebellum implements a forward internal model that transforms motor commands into predictions about upcoming movements
Two variants of the paradigm were studied in which the visual feedback was altered to understand the sources of the lead and lag simple spike (SS) modulation of the Purkinje cells (Fig. 1e) in the context of the forward model hypothesis
For the 30 Purkinje cells with significant encoding of position or velocity evaluated in the hidden cursor condition, there is no significant change in either lead or lag encoding of kinematics (Fig. 8i, F (1,113) = 0.01, p = 0.93, ANOVA) or the R2 (Fig. 8j, F(1,113) = 1.48, p = 0.23, ANOVA). These results show that SS modulation with kinematics during pseudo-random tracking reflects the encoding of limb movements, not the feedback associated with movement of the cursor
Summary
It is hypothesized that the cerebellum implements a forward internal model that transforms motor commands into predictions about upcoming movements. The simple spike firing of cerebellar Purkinje cells both lead and lag movement consistent with representations of motor predictions and sensory feedback. Consistent with a forward model, delaying the visual feedback demonstrates that the leading simple spike modulation with position error is time-locked to the hand movement. SS modulation both leads and lags behavior showing that individual Purkinje cells carry predictive and feedback signals about movements[16,17,18,19]. It is essential to establish that the feedforward and feedback SS signals of Purkinje cells respond to experimental manipulations as required of a forward internal model To address this issue, this study assessed how disrupting visual feedback during pseudorandom tracking alters the predictive and feedback SS activity. Red colors indicate higher discharge rates. g Temporal linear regression analysis results in R2 as a function of τ that quantifies the relation between SS activity and behavior
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
