Additional somatosensory information does not improve cerebellar adaptation during catching

Objective: People with cerebellar damage are impaired in their ability to a dapt anticipatory muscle activity during catching. We asked whether prior o r on-line information about ball weight and drop height could improve the i mpaired adaptation of people with cerebellar damage. Methods: Cerebellar and control subjects caught a series of balls of differ ent weights under two conditions. The first condition provided subjects wit h information about ball weight prior to the series of trials. The second c ondition provided subjects with information about ball weight, drop height, and time of ball release during the series of trials. Subjects had to main tain their hand within a vertical spatial 'window' during the catch. We mea sured 3-dimensional position and electromyography (EMG) from the catching a rm. Results: With prior information, controls required a few trials to adapt to a new ball weight. Cerebellar subjects were slow, or unable, to adapt. Wit h on-line information, controls were able to catch the ball within the wind ow immediately, showing that they did not require practice to make this adj ustment. Cerebellar subjects remained slow or unable to adapt to the change d ball weight even with on-line information. Conclusions: These results suggest that other, intact central nervous syste m structures cannot compensate for the role of the cerebellum in generating and adjusting anticipatory muscle activity across multiple joints. (C) 200 1 Elsevier Science Ireland Ltd. Ail rights reserved.