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Titolo:
INTERACTION OF NOCICEPTIVE AND NONNOCICEPTIVE CUTANEOUS AFFERENTS FROM FOOT SOLE IN COMMON REFLEX PATHWAYS TO TIBIALIS ANTERIOR MOTONEURONSIN HUMANS
Autore:
ROSSI A; ZALAFFI A; DECCHI B;
Indirizzi:
UNIV SIENA,IST SCI NEUROL,LAB NEUROFISIOL,VIALE BRACCI I-53100 SIENA ITALY
Titolo Testata:
Brain research
fascicolo: 1-2, volume: 714, anno: 1996,
pagine: 76 - 86
SICI:
0006-8993(1996)714:1-2<76:IONANC>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
MOTOR UNITS; ALPHA-MOTONEURONS; FLEXION REFLEX; LOWER-LIMB; STIMULATION; THRESHOLD; MUSCLES; RECRUITMENT; RESPONSES; CAT;
Keywords:
CUTANEOUS AFFERENT; SPINAL CONVERGENCE; SIZE PRINCIPLE; SEGMENTAL REFLEX; PAIN; VOLUNTARY COMMAND; HUMAN LOCOMOTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
42
Recensione:
Indirizzi per estratti:
Citazione:
A. Rossi et al., "INTERACTION OF NOCICEPTIVE AND NONNOCICEPTIVE CUTANEOUS AFFERENTS FROM FOOT SOLE IN COMMON REFLEX PATHWAYS TO TIBIALIS ANTERIOR MOTONEURONSIN HUMANS", Brain research, 714(1-2), 1996, pp. 76-86

Abstract

In six healthy subjects, the reflex responses of the tibialis anterior muscle (TA) to stimulation of the cutaneous afferents arising from plantar foot, were studied at rest and during different levels of steady voluntary contraction of the TA. At rest, the threshold of the response and the threshold of subjective pain sensation coincided. The meanlatency of this TA nociceptive response was 84.7 ms. Steady voluntarycontractions of the TA, which was increased progressively from 3% to 15% of the maximum voluntary contraction, produced a significant and parallel reduction in the threshold and latency of the response: at 15%, the mean latency was about 26 ms shorter than at rest and its threshold was about half (i.e. below the pain threshold). The conduction velocity of the afferents responsible for TA response at rest was within the range of A-delta pain afferents (mean 27.4 m/s), whereas during voluntary contraction it was within the A-beta fibre range (mean 45.1 m/s). This suggests that descending command makes the discharge of low-threshold, fast-conducting fibres sufficient for reflex activation of TA motoneurones (MNs). Central delay (about 4 ms) and MN recruitment order (according to the size principle) were found to be the same for both nociceptive and non-nociceptive TA reflex responses. Finally, experiments of spatial summation revealed an interaction between nociceptive and non-nociceptive inputs at a premotoneuronal level. It is therefore proposed that nociceptive and non-nociceptive cutaneous afferents arising from the foot sole use the same short-latency spinal pathway tocontact TA MNs and that their relative contribution to its segmental activation is contingent upon descending command.

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Documento generato il 28/11/20 alle ore 04:33:29