Motor impairment after unilateral electrolytic lesions of the substantia nigra in baboons: behavioral data with quantitative and kinematic analysis of a pointing movement.
Unilateral electrolytic lesions of the substantia nigra (SN) were carried out stereotaxically on 4 baboons which had been previously trained to perform a visually guided pointing movement. For a few days after operation, all animals exhibited a behavioral impairment affecting the contralateral body half and consisting of dystonic flexed posture and akinesia. The animals were thus unable to perform the pointing task with the contralateral hand. After a delay which depended on the extent of the SN lesion, the animals began to make the pointing movement again. Postoperative changes were then observed only on the side opposite the SN lesion. These consisted of an increase in the latency and particularly the duration of the movement without any change in the accuracy. The kinematic analysis of the hand trajectory showed that the contralateral increase in the movement duration corresponded to a regular decrease in the velocities. Study of the recovery over 120 days after SN lesion showed a progressive improvement which was faster with regard to movement duration than to movement latency. These data clearly point to the functional role of the SN in the initiation and particularly in the execution of movement. Quantitative and kinematic analysis of this pointing movement makes it possible to detect and quantify very closely the changes in movement program and execution induced by a SN lesion. This experimental model will be useful for pharmacological in vivo studies allowing a more specific assessment of the functional role of the neurotransmitters involved in SN dysfunction.
D000818:Animals; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology*; D009119:Muscle Contraction; D009132:Muscles / Q000294:innervation; D010215:Papio; D011187:Posture; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D013378:Substantia Nigra / Q000502:physiology*