Some Effects of Post-Tetanic Potentiation of Monosynaptic Response of Spinal Cord of Cat

The effect of repetitive stimulation upon monosynaptic transmission in kittens

“…Any dispersion of the reflex spikes would reduce their amplitudes, which would be against the argument. The use of the two sides of the body for this comparison is permissible because of the nearly symmetrical distribution of the motor axons in the comparable roots of the two sides (Jefferson & Benson, 1953; Eccles, REPETITIVE STIMULATION Kozak & Westerman, 1962). A control is provided by the use of both the L 7 and S 1 ventral roots, since most of the GS motor axons would pass through one or the other of these roots.…”

“…A control is provided by the use of both the L 7 and S 1 ventral roots, since most of the GS motor axons would pass through one or the other of these roots. Jefferson & Benson (1953) showed that, in adult cats, the reflex height usually attained the height of the antidromic spike after post-tetanic potentiation; whereas before potentiation only about 20-46 % of the neurones in a motoneuronal nucleus fired an impulse in response to a volley to its muscle nerve. It is significant that in three of the four pairs of records (Fig.…”

“…The proportion of the motoneuronal pool discharged by single afferent volleys in kittens. Figure 3 illustrates an experiment designed to estimate the proportion of motoneurones in two pools (MG and LGS) which could be fired by single volleys in the respective muscle nerves (Jefferson & Benson, 1953). The monosynaptic reflex discharges produced by maximal afferent volleys in the left MG and LGS nerves were recorded from the central ends of the cut L 7 and S 1 ventral roots on the left side of the spinal cord (Fig.…”

Motoneurone pool and the H-reflex.

“…The monosynaptic reflex response evoked in the cat by a maximal volley in the Group Ia afferent fibres from a synergic group of muscles (the triceps sural) has been measured as a fraction of total motoneurone pool of those muscles by Jefferson and Benson (1953) and found to range between 12-5 and 26-5 %. Apart from a preliminary report last year (Tabofikova, 1966) there has been no measurement of the activated fraction of the motoneurone pool in the analogous H-reflex.…”

Proceedings of the Physiological Society

“…Eccles (1953) has suggested an explanation of the potentiation in terms of swelling of the presynaptic terminals of the stimulated fibres, since heterosynaptic testing reveals no increase in excitability of the motoneurones. Jefferson & Benson (1953) expressed the opinion that in some experiments a portion of the potentiated ventral root response might represent the discharge of motoneurones of synergic muscles which have been activated by collateral fibres from the muscle afferents stimulated.…”