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Titolo:
Adaptive fusimotor reflex control in the decerebrate cat
Autore:
Murphy, PR;
Indirizzi:
Univ4HH,castle Upon Tyne, Sch Med, Dept Neurobiol, Newcastle Upon Tyne NE2Univ Newcastle Upon Tyne Newcastle Upon Tyne Tyne & Wear England NE2 4HH
Titolo Testata:
BRAIN RESEARCH
fascicolo: 1, volume: 821, anno: 1999,
pagine: 38 - 49
SICI:
0006-8993(19990306)821:1<38:AFRCIT>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
DISTAL HINDLIMB MUSCULATURE; UNRESTRAINED WALKING CATS; CUTANEOUS AFFERENTS; MUSCLE-SPINDLE; ELECTRICAL-STIMULATION; PREMAMMILLARY CATS; GAMMA-MOTONEURONS; TRICEPS SURAE; THIGH MUSCLES; IMPULSE RATES;
Keywords:
locomotion; reflex control; muscle spindle;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
54
Recensione:
Indirizzi per estratti:
Indirizzo: Murphy, PR Univ4HH,castle Upon Tyne, Sch Med, Dept Neurobiol, Newcastle Upon Tyne NE2 Univ Newcastle Upon Tyne Newcastle Upon Tyne Tyne & Wear England NE2 4HH
Citazione:
P.R. Murphy, "Adaptive fusimotor reflex control in the decerebrate cat", BRAIN RES, 821(1), 1999, pp. 38-49

Abstract

The effect of electrical stimulation of cutaneous afferents in the superficial peroneal nerve on the locomotor discharges of single medial gastrocnemius gamma-motoneurones has been investigated in a decerebrate cat preparation. Units were classified as static (n = 9) or dynamic (n = 7) indirectly on the basis of their resting and locomotor discharge characteristics. Brieftrains of stimulation, at 2 and 3 x threshold (T), were applied at rest and during locomotion. Responses were assessed by calculating the change in mean rate during the 100 ms after stimulus onset compared with a control period. At rest, static and dynamic gamma-motoneurones showed opposite responses. Static neurones were excited while inhibition was dominant with dynamicneurones. Effects were always present at 2T. During locomotion, inhibitoryresponses occurred with both types of gamma-motoneurone and excitation wasnot apparent. The inhibition of static neurones was maximum during (four units) or between (five units) EMG bursts and minimum in the opposite phase of EMG activity. For dynamic neurones, inhibition was not related to locomotor phase. Generally (six of seven units), the inhibition of dynamic gamma-motoneurones was reduced throughout the step cycle, including phases in which background discharge rates were comparable to resting levels. Latencies of response were measured from peristimulus time histograms. Subtraction ofperipheral conduction times gave estimated central delays of locomotor inhibition for static (2.4 +/- 0.2 ms, n = 6; mean +/- S.E.M.) and dynamic (2.2 +/- 0.2 ms, n = 7) gamma-motoneurones that were not significantly different (P > 0.1) and are consistent with spinal oligosynaptic pathways. We conclude that low threshold skin afferents from the foot dorsum are capable of influencing both types of gamma-motoneurone during walking through short latency spinal inhibitory pathways. Further, a highly specific (reciprocal) control of the reflex responses of static and dynamic gamma-efferents occursthat is dependent upon behavioural context. The results are discussed in relation to cutaneous effects on gamma-motoneurones which are suggested to form an adaptive control system. (C) 1999 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/09/20 alle ore 09:25:51