ISSN:
1432-1106
Keywords:
Load compensation
;
Motor cortex
;
Monkey
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary 1. Precentral neural activity was studied in relation to steady loads in a Cebus monkey trained to make self-paced elbow flexions and extensions into learned target positions in which the arm had to be held steady between movements. The same steady loads were applied in about 15 successive trials. 2. Single unit records were analyzed from 75 task-related precentral cortical cells. Out of 57 activated neurons, 18 reached peak discharge before or at movement onset, 31 after movement onset, and 8 had gradually rising discharge throughout holding and movement. 3. Different steady loads were tested adequately for 52 neurons. Of these 13 displayed a clear increase of the static discharge rate during the hold phase; a weak trend in the same direction was seen in additional 11 neurons. Four neurons appeared to be related to position rather than to load, and 24 neurons did not change their static discharge rate under different loads. 4. Increasing load produced also dynamic changes of firing frequency in 8 neurons: an increase of the peak frequency, a shortening of the rise time to peak, and advanced onset time. Increased peak frequency was positively correlated with increased peak acceleration of the movement. 5. It is likely that these dynamic changes occurring before or shortly after movement onset are programmed and not the consequence of proprioceptive feedback.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00236877
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