The neural mechanisms underlying spontaneous tremor were investigated in monkeys. Tremor-producing ventromedial tegmental (VMT) lesions involve at least three major neural elements. (1) Parvocellular division of the red nucleus (RNpc); (2) cerebellothalamic fibers passing through the red nucleus, and, (3) nigrostriatal fibers. These three elements were destroyed stereotaxically in areas remote from the VMT area separately and/or in various combinations, and correlation between the site of lesions and tremor was made. Lesion-induced tremor appeared only when the three elements were destroyed. A possible, particular role of the RNpc in the production of the spontaneous tremor is discussed.

Animals↗

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Plasma-induced instability of reverse-phase evaporation vesicles.

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Drug Stability↗

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[Neuronal behavior of the striatum in man].

Units of the caudate and putamen were studied during stereotactic operations in 11 patients with movement disorders. Responses of these units to different visual stimuli were found for cells of the caudate nucleus head. These units were activated mainly during the presentation of nutritional stimuli. The responses appeared when a slide was shown presenting an image of drink or food or the corresponding word. Frequently the same unit was activated by slides of the image and the word presented in succession. Responses to similar stimulations were not observed in the putamen. Among the parkinsonian patients, only those with tremor had responsive cells while the rigid patients had not. This discrepancy was correlated with the lowering of cortical metabolism demonstrated by PET scan in the rigid group of patients. These results are in agreement with those obtained in monkeys during food presentation. They present, moreover, the advantage of showing that these responses could be provoked in man by more abstract stimuli, not only the image but the name of the object. These observations do not imply a long testing period; 2 or 3 cells only are studied in each patient. They have the advantage for the patient of ascertaining the position of the trajectory in the striate structure, in the same way as thalamic nuclei are delineated using other types of stimuli. Moreover, it is of interest to have a better knowledge of the behavioral role played by different striatal regions at a time when lesions or stimulations at this level are proposed to cure abnormal movements in human.

Behavior↗