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Titolo:
Large involuntary forces consistent with plateau-like behavior of human motoneurons
Autore:
Collins, DF; Burke, D; Gandevia, SC;
Indirizzi:
Prince Wales Med Res Inst, Spinal Injury Res Ctr, Randwick, NSW 2031, Australia Prince Wales Med Res Inst Randwick NSW Australia 2031 NSW 2031, Australia Univ New S Wales, Randwick, NSW 2031, Australia Univ New S Wales RandwickNSW Australia 2031 andwick, NSW 2031, Australia
Titolo Testata:
JOURNAL OF NEUROSCIENCE
fascicolo: 11, volume: 21, anno: 2001,
pagine: 4059 - 4065
SICI:
0270-6474(20010601)21:11<4059:LIFCWP>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
POST-ACTIVATION DEPRESSION; MOTOR UNITS; H-REFLEX; SPINAL MOTONEURONS; HINDLIMB MOTONEURONS; DECEREBRATE CATS; TRICEPS SURAE; IN-VIVO; BISTABILITY; POTENTIALS;
Keywords:
human; motoneuron; muscle force; spinal cord; reflex; muscle contraction; plateau potential;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Gandevia, SC Prince Wales Med Res Inst, Spinal Injury Res Ctr, Barker St, Randwick, NSW2031, Australia Prince Wales Med Res Inst Barker St Randwick NSW Australia 2031
Citazione:
D.F. Collins et al., "Large involuntary forces consistent with plateau-like behavior of human motoneurons", J NEUROSC, 21(11), 2001, pp. 4059-4065

Abstract

When electrical stimulation is applied over human muscle, the evoked forceis generally considered to be of peripheral origin. However, in relaxed humans, stimulation (1 msec pulses, 100 Hz) over the muscles that plantarflexthe ankle produced more than five times more force than could be accountedfor by peripheral properties. This additional force was superimposed on the direct response to motor axon stimulation, produced up to 40% of the force generated during a maximal voluntary contraction, and was abolished during anesthesia of the tibial nerve proximal to the stimulation site. It therefore must have resulted from the activation of motoneurons within the spinal cord. The additional force could be initiated by stimulation of low-threshold afferents, distorted the classical relationship between force and stimulus frequency, and often outlasted the stimulation. The mean firing rate of 27 soleus motor units recorded during the sustained involuntary activity after the stimulation was 5.8 +/- 0.2 Hz. The additional force increments were not attributable to voluntary intervention because they were present inthree sleeping subjects and in two subjects with lesions of the thoracic spinal cord. The phenomenon is consistent with activation of plateau potentials within motoneurons and, if so, the present findings imply that plateau potentials can make a large contribution to forces produced by the human nervous system.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 14:26:54