Pattern of projections of group I afferents from forearm muscles to motoneurones supplying biceps and triceps muscles in man
Tóm tắt
(1) Two independent methods were used, in man, to assess the modifications of the excitability of biceps and triceps brachii motoneurone pools following the stimulation of group I afferents coming from muscles acting at the wrist: (a) the modifications of the excitability of a motoneuronal population were studied using a reflex technique, (b) the modifications of the excitability of an isolated motor unit were estimated using a post-stimulus time histogram (p.s.t.h.) method. (2) The activation of group I afferents contained in the median nerve, originating from wrist flexors and pronators, resulted in a strong, short-latency facilitation of the biceps brachii motoneurones. A similar effect was also evoked by stimulation of group I afferents in the radial nerve, distally to the branch supplying the brachio-radialis muscle. The latency of both median and radial-induced facilitations is compatible with a monosynaptic linkage. (3) The stimulation of group I afferents in the median or the radial nerves produced inhibition of triceps motoneurones, with a latency compatible with a disynaptic linkage. (4) The prolonged vibration of the tendon of the flexor carpi radialis (FCR) or of the extensor carpi radialis (ECR) raised the threshold for both the facilitation of biceps and the inhibition of triceps motoneurones. The same pattern of excitatory and inhibitory convergence could also be obtained when the electrical conditioning stimulus to the median or radial nerves was replaced by a tap applied to the tendons of FCR or ECR respectively. Both results suggest that the conditioning fibres were Ia fibres. (5) The pattern of distribution of Ia afferents from muscles acting at the wrist onto motoneurones of muscles acting at the elbow has been compared to that described in the cat and monkey. A comparison has also been made between Ia connections of muscles acting at different joints in the upper and lower limb in man. The differences are discussed in relation to the manipulating capacity of the hand.
Tài liệu tham khảo
Baldissera F, Campadelli P, Cavallari P (1983) Inhibition of H-reflex in wrist flexors by group I afferents in the radial nerve. Electromyogr Clin Neurophysiol 23:187–193
Bratzlavski M, Isch F, Vander Eechen H (1971) Study of evoked responses in proximal muscles of the superior and inferior limbs. Eur Neurol 5:171–186
Buchtal F, Rosenfalk A (1966) Evoked action potentials and conduction velocity in human sensory nerves. Brain Res 3:1–122
Cavallari P, Fournier E, Katz R, Pierrot-Deseilligny E, Shindo M (1984) Spinal projections of group I fibres from wrist flexors and extensors in man. Neurosci Lett [Suppl] 18:395
Cavallari P, Fournier E, Katz R, Malmgren K, Pierrot-Deseilligny E, Shindo M (1985) Cutaneous facilitation of transmission in Ib reflex pathway in human upper limb. Exp Brain Res 60:197–199
Clough JFM, Kernell D, Phillips CG (1968) The distribution of monosynaptic excitation from the pyramidal tract and from primary spindle afferents to motoneurones of the baboon's hand and forearm. J Physiol (Lond) 598:145–166
Coppin CMC, Jack JJB, MacLennan CR (1970) A method for the selective electrical stimulation of tendon organ afferent fibres from the cat soleus muscle. J Physiol (Lond) 210:18p-20p
Day BL, Marsden CD, Obeso JA, Rothwell JC (1984) Reciprocal inhibition between the muscles of the human forearm. J Physiol (Lond) 349:519–534
Eccles JC, Eccles RM, Lundberg A (1957) The convergence of monosynaptic excitatory afferents onto many different species of alpha-motoneurones. J Physiol (Lond) 137:22–50
Fetz EE, Gustafsson B (1983) Relation between shapes of postsynaptic potentials and changes in firing probability of cat motoneurones. J Physiol (Lond) 341:387–410
Fetz E, Jankowska E, Johannisson T, Lipski J (1979) Autogenetic inhibition of motoneurones by impulses in group Ia muscle spindle afferents. J Physiol (Lond) 293:173–195
Fournier E, Meunier S, Pierrot-Deseilligny E, Shindo M (1986) Evidence for interneuronally mediated Ia excitatory effects to human quadriceps motoneurones. J Physiol (Lond) 377:146–169
Fritz N, Illert M (1981) Basic principles of Ia connections in the cat forelimb. Neurosci Lett [Suppl] 7:S347
Gustafsson B, McCrea D (1984) Influence of stretch-evoked synaptic potentials on firing probability of cat spinal motoneurones. J Physiol (Lond) 347:431–451
Heckman CJ, Condon MS, Hutton RS, Enoka RM (1984) Can Ib axons be selectively activated by electrical stimuli in human subjects? Exp Neurol 86:576–582
Hongo T, Lundberg A, Phillips CG, Thomspon RF (1984) The pattern of monosynaptic Ia-connections to hindlimb motor nuclei in the baboon: a comparison with the cat. Proc R Soc London Ser B 221:261–289
Jankowska E, McCrea D, Mackel R (1981a) Pattern of “non reciprocal” inhibition of motoneurones by impulses in group Ia muscle spindle afferents. J Physiol (Lond) 316:393–409
Jankowska E, McCrea D, Mackel R (1981b) Oligosynaptic excitation of motoneurones by impulses in group Ia muscles spindle afferents in the cat. J Physiol (Lond) 316:411–425
Katz R, Morin C, Pierrot-Deseilligny E, Hibino R (1977) Conditioning of H-reflex by a preceding subthreshold tendon reflex stimulus. J Neurol Neurosurg Psychiatr 40:575–580
Lundberg A, Winsbury G (1960) Selective adequate activation of large afferents from muscle spindles and Golgi tendon organs. Acta Physiol Scand 49:155–164
Magladery JW, Porter WE, Park AM, Tesdall RD (1951) Electrophysiological studies on nerve and reflex activity in normal man. IV. Two neurone reflex and identification of certain action potentials from spinal roots and cord. Bull Johns Hopkins Hosp 88:491–519
Malmgren K, Pierrot-Deseilligny E (1988) Evidence for nonmonosynaptic Ia excitation of wrist flexor motoneurones, possibly via propriospinal neurones. J Physiol (Lond) 405:747–764
Mao C, Ashby P, Wang M, McCrea D (1984) Synaptic connections from large muscle afferents to the motoneurones of various leg muscles in man. Exp Brain Res 56:341–350
Pierrot-Deseilligny E, Mazières L (1984) Circuits réflexes de la moelle épinière chez l'homme: contrôle au cours du mouvement et rôle fonctionnel (2ème partie). Rev Neurol (Paris) 140:681–694
Pierrot-Deseilligny E, Morin C, Bergego C, Tankov N (1981) Pattern of group I fibre projections from ankle flexor and extensor muscles in man. Exp Brain Res 42:337–350
Rosen I, Sjölund D (1973) Organisation of group I activated cells in the main and external cuneate nuclei of the cat: identifications of muscle receptors. Exp Brain Res 16:221–234
Schmidt RF, Willis WD (1963) Intracellular recordings from motoneurones of the cervical spinal cord of the cat. J Neurophysiol 26:28–43
Stephens JA, Usherwood TP, Garnett R (1976) Technique for studying synaptic connections of single motoneurones in man. Nature 263:343–344
Willis ND, Tate JW, Ashworth RD, Willis JC (1966) Monosynaptic excitation of motoneurones of individual forelimb muscles. J Neurophysiol 29:410–424