SPATIOTEMPORAL AND KINEMATIC ANALYSIS OF POINTING MOVEMENTS PERFORMEDBY CEREBELLAR PATIENTS WITH LIMB ATAXIA

Three patients with cerebellar limb ataxia and three age-matched contr ols performed arm-pointing movements towards a visual stimulus during an experimental procedure using a double-step paradigm in a three-dime nsional space. Four types of trajectories were defined: P1, single-ste p pointing movement towards the visual stimulus in the initial positio n S1; P2, double-step pointing movement towards S1; P3, double-step st raight pointing movement towards the second position S2; and P4, doubl e-step pointing movement towards S2 with an initial direction towards S1. We found that the cerebellar patients, as well as the controls, we re able to modify their motor programs, but with impaired timing, seve re anomalies in the direction and amplitude of the changed movement tr ajectories and alteration of the precision of the pointing movements.