Jeffrey G Keating

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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)
In trained reaching rats, we recorded simple spikes of pairs of Purkinje cells that, with respect to each other, were either aligned on a beam of shared parallel fibers or instead were located off beam. Rates of simple spike firing in both on-beam and off-beam Purkinje cell pairs commonly showed great variety in depth of modulation during reaching behavior.(More)
1. Complex spikes of cerebellar Purkinje cells recorded from awake, behaving monkeys were studied to determine the extent to which their discharge could be quantified as periodic. Three Rhesus monkeys were trained to perform up to five different tasks involving rotation of the wrist in relation to a visual cue. Complex spike activity was recorded during(More)
Purkinje cells are the only output neurons in the cerebellar cortex, which plays a vital if poorly understood role in the coordination of movement. Purkinje cells show two forms of activity. Complex spikes (CS) occur at a low frequency and are driven by excitatory input from a single climbing fiber, whereas simple spikes (SS) occur at much higher frequency(More)
We examined the spike activity of deep cerebellar nuclear cells recorded from awake, behaving monkeys to determine if there was a tendency for periodic discharge at or near 10 Hz. Data were obtained from four Rhesus monkeys trained to perform either targeted flexions and extensions of the wrist in relation to a visual cue (2 monkeys) or instrumented digit(More)
A patient with an infarct in the distribution of the right superior cerebellar artery was studied with regard to his ability to make simple movements (visually triggered, self-terminated ballistic wrist movements), and compound movements (reaching to a visual target and precision pinch of a seen object). Movements on the right side of the body alone were(More)
A number of studies have been interpreted to support the view that the inferior olive climbing fibers send periodic signals to the cerebellum to time and pace behavior. In a direct test of this hypothesis in macaques performing nonperiodic tasks, we analyzed continuous recordings of complex spikes from the lateral cerebellar hemisphere. We found no(More)