State estimation and the cerebellum - By Chris Miall | BCBT 2010 - Barcelona Cognition, Brain and Technology Summer School

Start: 09/07/2010 - 10:45

End: 09/07/2010 - 12:00

The role of the cerebellum in motor control is still uncertain. A prominent theory is that the cerebellum holds an “internal model” of the sensory-motor system. This is a crucial component in the process of “state estimation” combining information from descending motor commands and ascending sensory afferent signals to predict the outcome of actions, and helping determine the current state of the motor system. Without state estimation, feedback delays in sensory pathways would degrade performance. A state estimate would also underpin coordinated actions. This would explain the contribution the cerebellum makes to control action, as inaccuracy in state estimates would lead to hypometria and dyscoordination similar to that observed in cerebellar ataxia.

In this lecture I describe studies from my laboratory that support this theory, using simple laboratory-based motor tasks to explore the coordination of eye and hand actions. Studies include testing the effects of extending visual feedback delays to disturb state estimation, recording neuronal activity, and functional imaging of the cerebellum during hand-eye coordination. We are also using transcranial magnetic brain stimulation of the cerebellum to disrupt its operation, causing errors in reaching movements. The errors suggest the cerebellum is normally responsible for estimating the hand position over an interval of about 140 ms. These studies will be discussed in terms of the challenge of motor control even in full health. I will end with some speculation on cognitive functions.

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State estimation and the cerebellum - By Chris Miall

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