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Science 29 September 1978:
Vol. 201. no. 4362, pp. 1235 - 1237
DOI: 10.1126/science.99813
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Articles

Science, Vol 201, Issue 4362, 1235-1237
Copyright © 1978 by American Association for the Advancement of Science

articles

Processes controlling arm movements in monkeys

A Polit and E Bizzi

The experiments identify some of the processes underlying arm movements in rhesus monkeys. Three monkeys were trained to point to a target with the hand and forearm and to hold that position for about 1 second to obtain a reward. Forearm movements were performed without sight of the arm before and after bilateral dorsal rhizotomy. In both intact and deafferented animals, we unexpectedly displaced the forearm prior to movement initiation and observed that the arm moved accurately to the target. These results are relevant to the question of what is being controlled by motor commands. The controlled variable appears to be an equilibrium point between agonist and antagonist muscles. The findings suggest that the feedback system plays a major role in updating and adjusting the central programs subserving the execution of learned motor patterns.


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