RECOVERY OF FUNCTION FOLLOWING UNILATERAL LESIONS OF THE BULBAR PYRAMID IN THE MONKEY
RECOVERY OF FUNCTION FOLLOWING UNILATERAL LESIONS OF THE BULBAR PYRAMID IN THE MONKEY
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DOI:
10.1016/0013-4694(82)90003-7
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发表时间:
1982-01-01
期刊:
影响因子:
--
通讯作者:
WIESENDANGER, M
中科院分区:
文献类型:
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作者:
CHAPMAN, CE;WIESENDANGER, M
Following unilateral pyramidotomy in the monkey, deficits in skilled movements and muscle tone were quantified and the time course for their return was studied. Three monkeys [M. fascicularis] were trained preoperatively to perform a timed retrieval task on the Kluver board, which required digital dexterity and quick arm movements. Following pyramidotomy (involving 66%, 85% and 87% of the pyramid), performance initially was severely impaired because of slowing of arm movements and impaired manual dexterity, especially in the retrieval of food from small wells. Performance gradually improved until, by 4-5 wk after the lesion, all animals had recovered to preoperative control levels. Recovery was attributed to: increased speed of arm movements, a change in the movement strategy whereby the animal used all 4 fingers instead of the precision grip for retrieving food from large wells; and some recovery of independent finger movements. Close inspection of videotapes revealed that the finger movements were still clumsy after full recovery of the measured performance. Control of discrete finger movements may be re-established to some extent after a subtotal lesion of the bulbar pyramid. Muscle tone was assessed by recording EMG [electromyograph] responses to torque perturbations during the performance of a postural task. During the 2nd postoperative week, contralateral elbow flexors and extensors in 1 monkey showed a marked hypotonia and hyporeflexia which was characterized by a decrease in the amplitude and an increase in the latency for all components of the reflex response to an 80-ms torque. Background activity was also reduced. Little recovery was seen when the records were repeated 8-9 wk after the lesion, i.e., after recovery on the manual task was complete. In another monkey, elbow flexor and extensor stretch reflexes in the 2 arms were compared 1.5 yr postoperatively. There was no difference between the triceps EMG responses to stretch. The contralateral biceps stretch responses were reduced and delayed compared to the ipsilateral arm. There was a marked modulation of the amplitude of the biceps stretch response when the pre-load was changed, which had not been observed during either control or early postoperative recordings. Hyporeflexia apparently persists in elbow flexors, but not extensors. The pyramidal tract apparently has a tonic influence on spinal cord activity and may also have an important function in the control of postural activity.