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Titolo:
Orderly recruitment among motoneurons supplying different muscles
Autore:
Cope, TC; Sokoloff, AJ;
Indirizzi:
Emory Univ, Sch Med, Dept Physiol, Atlanta, GA 30322 USA Emory Univ Atlanta GA USA 30322 Med, Dept Physiol, Atlanta, GA 30322 USA
Titolo Testata:
JOURNAL OF PHYSIOLOGY-PARIS
fascicolo: 1-2, volume: 93, anno: 1999,
pagine: 81 - 85
SICI:
0928-4257(199901/04)93:1-2<81:ORAMSD>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
MOTOR-UNIT RECRUITMENT; DECEREBRATE CAT; HINDLIMB; FOREARM;
Keywords:
size principle; motoneuron; motor unit; motor control; muscle;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
26
Recensione:
Indirizzi per estratti:
Indirizzo: Cope, TC Emory Univ, Sch Med, Dept Physiol, Atlanta, GA 30322 USA Emory Univ Atlanta GA USA 30322 t Physiol, Atlanta, GA 30322 USA
Citazione:
T.C. Cope e A.J. Sokoloff, "Orderly recruitment among motoneurons supplying different muscles", J PHYSL-PAR, 93(1-2), 1999, pp. 81-85

Abstract

Virtually all movements involve the recruitment of motor units from multiple muscles. Given the functional diversity of motor units (motoneurons and the muscle fibers they supply), the effective production of specific movements undoubtedly depends upon some principle(s) to organize the ensemble of active motor units. The principle acting to organize the recruitment of motor units within muscles is the size principle, whereby the first motor units to be recruited have the smallest values for axonal conduction velocity and contractile force, and are the slowest to contract and fatigue. Here we consider the possibility that the size principle applies in the recruitmentof motor units across muscles, i.e., that regardless of their muscles of origin, active motor units are recruited in rank order, for example, from low to high conduction velocity. The benefits of orderly recruitment across muscles could be similar to the acknowledged advantages of orderly recruitment within muscles. One benefit is that the neural process involved in organizing active motor units would be simplified. In a muscle-based scheme, thesize principle would organize only those motor units within individual muscles, leaving the nervous system with the additional task of coordinating the relative activities of motor units from different muscles. By contrast, in an ensemble-based scheme, orderly recruitment of all motor units according to the size principle would automatically coordinate motor units both within and across motor nuclei. Another potential benefit is the provision for movements with smooth trajectory, the result of interleaving the divergent torque contributions made by motor units from muscles that differ in their orientations about joints. Otherwise, if order were restricted within muscles, the torque trajectory of a joint would change unevenly as participating muscles begin contracting at different times and grade activity at different rates. These considerations support speculation that motor units recruited from co-contracting muscles are collectively recruited according to the size principle. (C) Elsevier, Paris.

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Documento generato il 02/12/20 alle ore 04:54:47