CEREBELLAR HYPERMETRIA IS LARGER WHEN THE INERTIAL LOAD IS ARTIFICIALLY INCREASED

Hypermetria is a classical cerebellar symptom designating the overshoo t observed when a patient is asked to make a very fast and accurate mo vement. The movement studied here was wrist flexion. Hypermetria was f ound to be increased by artificially increasing the inertia of the mov ing hand. A normal subject adapted himself to increasing inertia by in creasing both his agonist activity (the launching force) and its antag onist activity (the braking force). In the same circumstances, a patie nt with symptoms of cerebellar system dysfunction was found to be able to increase his agonist activity but not his antagonist activity.