Reflex Effects of Tetnnic Stimulation of Different Afferent Fibre‐Systems in the Hind Limb of the Cat

Abstract

I n order to study the reflex effects of activity in different afferent systems one has often in recent work made use of single shock stimulation of a peripheral nerve. I n this way LLOYD (1943, 1946) has carried out a systematic investigation of the coordinated reflex function of different myelinated afferent fibre groups in the hind limb of the cat. Thus it was shown that a single conditioning shock of the large proprioceptive muscle afferents caused a direct facilitation of the synergists and a direct inhibition of the antagonists a t the same joint. A single conditioning shock of the smaller afferent fibres caused an indirect facilitation of the flexors and an indirect inhibition of the extensors.Considering that the sense organs discharge iteratively it is likely that further information about coordinated reflex activity would be gained from an investigation of the central effects produced by tetanic stimulation of the different afferent fibre systems.Several authors have earlier studied how different reflex functions in the spinal cord are affected by prolonged tetanic stiniulation. In these experiments, however, one has generally not taken care to select the effects from the different affgrent fibre systems. Since, in addition the ventral roots have been left intact antidromic effects have complicated the understanding of the results.

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

“…It is a fairly general finding that, following a period of intense repetitive bombardment, synapses exhibit a prolonged increase in effectiveness, which has been called post-tetanic potentiation (Lloyd, 1949(Lloyd, , 1952Hagbarth & Naess, 1951;Eccles & Rall, 1951;Str6m, 1951). Fig.…”

Synaptic action during and after repetitive stimulation

“…Granit, 1955). Repetitive synaptic activation of motoneurones has been studied by the monosynaptic reflex discharges generated thereby (Hagbarth & Naess, 1951;Eccles & Rall, 1951a;Jefferson & Schlapp, 1953; Alvord & Fuortes, 1953;Fuortes & Hubel, 1956;Evanson, 1956; Lloyd & Wilson, 1957;Lloyd, 1957a, b) and by the synaptic potentials recorded either extracellularly or after electrotonic spread to the ventral root (Eccles, 1946;Eccles & Rall, 1951a). In the present investigation repetitive synaptic activation has been studied in detail by intracellular recording from motoneurones.…”

The Reactions to Tetanic Stimulation of the Two‐Neuron Arc in the Kitten

“…1 it is however quite obvious that the period of unresponsiveness following tetanization is considerably longer in the newborn animal than in the adult, as determined for the latter by ECCLES and RALL (1951 a). Furthermore, each shock is not followed by a small monosynaptic potential as has been found to be the case in the adult animal ( HAGBARTH andNAESS 1951, ECCLES andRALL 1951 b). This is also in accordance with the findings presented in a preceding paper (SKOCLUND 1960 c) according to which there is no early Fig.…”