William Thomas Thach

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Normal human subjects and patients with lesions of the olivocerebellar system threw balls of clay at a visual target while wearing wedge prism spectacles. Normal subjects initially threw in the direction of prism-bent gaze, but with repeated throws adapted to hit the target. Patients with generalized cerebellar atrophy, inferior olive hypertrophy, or focal(More)
1. We studied seven subjects with cerebellar lesions and seven control subjects as they made reaching movements in the sagittal plane to a target directly in front of them. Reaches were made under three different conditions: 1) "slow-accurate," 2) "fast-accurate," and 3) "fast as possible." All subjects were videotaped moving in a sagittal plane with(More)
Human subjects threw balls of clay at a visual target while looking through wedge prism spectacles. In studies of short-term adjustment, subjects threw in the direction of their prism-bent gaze, missing the target to that side. Within 10-30 throws, they gradually adapted with a wider gaze-throw angle and hit the target. Immediately after removal of the(More)
Based on a review of cerebellar anatomy, neural discharge in relation to behavior, and focal ablation syndromes, we propose a model of cerebellar function that we believe is both comprehensive as to the available information (at these levels) and unique in several respects. The unique features are the inclusion of new information on (a) cerebellar(More)
1. Monkeys were trained to grasp a rod movable in a horizontal arc (Fig. 1), and to hold the rod by angulation of the wrist in each of three positions (A,B, C). A maintained load was placed on the rod alternately to oppose flexion and extension. At a light signal, the monkey had to move to the next position in a prescribed sequence (ABCBABCBA, ETC.). The(More)
1. Inactivation of the portions of globus pallidus pars interna (GPi) containing the greatest concentration of wrist-related neurons was achieved in two rhesus monkeys with microinjections of muscimol (temporary) and kainic acid (permanent). 2. After muscimol injection, there was onset within 30 s of 1) tonic and phasic coactivation of wrist flexors and(More)
The efferent projections of the deep cerebellar nuclei were studied and their fiber trajectories and thalamic termination zones described. The thalamic termination zones for the dentate, interposed and fastigial nuclei are identical and coincide with the cytoarchitectonically unique cell-sparse region of the ventral lateral complex. This region includes(More)
Monkeys were trained to grasp a handle and move it in a horizontal arc to a central position by flexing or extending the wrist. A torque motor applied forces to the handle that switched at random intervals to alternately load flexor and extensor muscles. At each load switch, the handle was displaced transiently from the central position, and then moved back(More)
1. To evaluate the various hypotheses that the basal ganglia preferentially control one mode of movement to the exclusion of others, we recorded the discharge of single neurons in the globus pallidus (GP) in rhesus monkeys during their performance of five trained wrist-movement tasks. The tasks were designed to dissociate several modes and parameters of(More)