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In the primate striatum, the tonically discharging neurons respond to conditioned stimuli associated with reward. We investigated whether these neurons respond to the reward itself and how changes in the behavioral context in which the reward is delivered might influence their responsiveness. A total of 286 neurons in the caudate nucleus and putamen were(More)
The ability of 13 Parkinsonian patients and 11 age-matched control subjects to process and use two components of the information given prior to a voluntary movement was studied using reaction time (RT) tasks. This advance information about the direction of a pointing movement was given using a double stimulation paradigm with an auditory warning signal (WS)(More)
Experiments carried out on seven adult baboons were addressed at specifying the participation of the cerebellar dentate nucleus (DN) in the control of duration and accuracy of a goal-directed movement. The visuo-motor task used in this experiment involved trained pointing movement towards stationary target. The monkeys trained to point with the index finger(More)
Unilateral lesions of the nigrostriatal dopaminergic system were induced by injecting 6-hydroxydopamine into the substantia nigra of three monkeys trained to initiate arm movements in response to stimuli randomly presented at various locations in their immediate visual space. This procedure resulted in partial reduction of dopamine content, as compared to(More)
In studies on the motor impairments induced in monkeys by performing lesions of various kinds on the central nervous system, it is necessary to be able to exactly quantify the motor deficits. The battery of tests described in the present paper (simple and choice reaction-time procedures, goal-directed pointing movement, digital manipulation task) provide a(More)
Three patients with cerebellar limb ataxia and three age-matched controls performed arm-pointing movements towards a visual stimulus during an experimental procedure using a double-step paradigm in a three-dimensional space. Four types of trajectories were defined: P1, single-step pointing movement towards the visual stimulus in the initial position S1; P2,(More)
The participation of the dentate nucleus (DN) in the initiation of a voluntary movement was investigated in five baboons (Papio papio). In these experiments, we have analyzed the effects of excluding the DN on the latency (reaction time, RT) of a learned goal-directed movement. Two techniques were for excluding the DN. In three animals, the structure was(More)
In order to elucidate the compensatory role of visual feedback during movement, two experiments were designed to compare the motor performances of Papio papio baboons depending on whether the animals were able to visually control the limb trajectory (visual closed-loop condition) or not (visual open-loop condition). The visuomotor task used consisted of(More)
Unilateral lesions were made in the substantia nigra of baboons which had been previously trained to carry out a visually guided pointing movement. During the early post-operative period, the animals were unable to perform the task with the contralateral forelimb because of the severity of the akinesia affecting it. After one or two weeks, the animals began(More)
To test whether the responsiveness of tonically discharging neurons from monkey striatum is dependent on the motor or rewarding features of the conditioned stimuli, we studied the responses of these neurons to visual stimuli presented under two behavioral conditions: during an operant task in which the stimulus triggered a movement to obtain a reward, and(More)