Abstract
A prevailing view is that the cerebellum is the site of a forward model that predicts the expected sensory consequences of self-generated action. Changes in motor apparatus and/or environment will cause a mismatch between the cerebellum's prediction and the actual resulting sensory stimulation. This mismatch - the 'sensory prediction error,' - is thought to be vital for updating both the forward model and motor program during motor learning to ensure that sensory-motor pathways remain calibrated. However, where and how the brain compares expected and actual sensory feedback was unknown. In this talk, I will first review experiments that focused on a relatively simple sensory-motor pathway with a well-described organization to gain insight into the computations that drive motor learning. Specifically, the most medial of the deep cerebellar nuclei (rostral fastigial nucleus), constitutes a major output target of the cerebellar cortex and in turn sends strong projections to the vestibular nuclei, reticular formation, and spinal cord to generate reflexes that ensure accurate posture and balance. Trial by trial analysis of these neurons in a motor learning task revealed the output of a computation in which the brain selectively encodes unexpected self-motion (vestibular information). This selectively enables both the i) rapid suppression of descending reflexive commands during voluntary movements and ii) rapid updating of motor programs in the face of changes to either the motor apparatus or external environment. I will then consider the implications of these findings regarding our recent work on the thalamo-cortical processing of vestibular information.
Meeting abstract presented at VSS 2018