Spinal cord potentials generated by volleys in the large muscle afferents

Abstract

It has now been established that the large muscle afferent fibres, i.e. the group I afferent fibres of muscle nerves, are separable into two quite distinct groups, I a and I b, the former arising from the annulo-spiral endings of the muscle spindles, the latter from the Golgi tendon organs (Matthews, 1933; Bairker, 1948; Hunt & Kuffler, 1951; Hunt, 1952 Hunt, , 1953. Furthermore, impulses in the group Ia and Ib afferent fibres have quite distinct actions within the spinal cord (Granit, 1950(Granit, , 1952Laporte & Lloyd, 1952;Bradley & Eccles, 1953; Hunt & Kuffler, 1951; Hunt, 1952 Renshaw, 1946) has shown that with microelectrode recording it is possible to identify the pre-and post-synaptic components of the monosynaptic myotatic reflex, and to subdivide the total central delay of this reflex into a pre-synaptic conduction time, a true synaptic delay in the initiation ofthe synaptic potential, and finally post-synaptic events.The present investigation is an extension of this earlier work; not only is there a study of the time relations of the synaptic events evoked by group Ia and I b afferent volleys, but there has been approximate mapping of the potential fields generated in the spinal cord by their respective synaptic actions. In 1945 Campbell published elaborate maps of the potential fields generated in the spinal cord by an afferent volley, but unfortunately this volley was com-

Cholinergic and inhibitory synapses in a pathway from motor‐axon collaterals to motoneurones

“…9 B) showing the focus for maximum response, exactly as has been done for other potential waves (Eccles, Fatt, Landgren & Winsbury, 1954). But, in addition, such systematic investigations revealed a remarkable feature, a reversal of the phase of the rhythmic wave.…”

“…The microelectrode techniques for the intracellular recording of electric potentials from motoneurones and for the exploration of extracellular potential fields among groups of neurones have been described in recent papers (Brock, Coombs & Eccles, 1952;Eccles, Fatt, Landgren & Winsbury, 1954).…”

The electrical properties of the motoneurone membrane

“…The technique of micromanipulation was the same as that described by Eccles, Fatt, Landgren & Winsbury (1954).…”

Proceedings of the Physiological Society

“…The depressant effect of adrenaline on sympathetic ganglia has already been described by Marazzi (1939), Bulbring & Burn (1942) Eccles, Fatt, Landgren & Winsbury, 1954) suggest that it arises in secondary neurones. Its afferents are the largest 9P pPROCEEDINGS OF THE PH YSIOLOGICAL from the skin, probably those from hair follicles; the efferent pathway is unknown.…”