The Supernormal Period in the Recovery Cycle of Motoneurons

Hoff, H. E.; Grant, R. S.

doi:10.1152/jn.1944.7.5.305

Cited by 43 publications

(19 citation statements)

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“…Incidentally our results throw fresh light on the origin of double spikes from motoneurones, a subject on which there is a large literature (Eccles & Hoff, 1932;Gilson & Mills, 1941;Hoff & Grant, 1944;Denslow, 1948;Toennies & Jung, 1948;Gordon & Holbourn, 1949). They do so by demonstrating the connexion of this phenomenon with level of excitability and with some recent intracellular observations.…”

Section: Discussionsupporting

confidence: 75%

The behaviour of tonic α and β motoneurones during stimulation of recurrent collaterals

Granit¹,

Pascoe²,

Steg³

1957

The Journal of Physiology

152

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Section: Discussionsupporting

confidence: 75%

The behaviour of tonic α and β motoneurones during stimulation of recurrent collaterals

Granit¹,

Pascoe²,

Steg³

1957

The Journal of Physiology

152

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“…The possible importance of block of the second impulse in a double discharge was investigated by stimulating the nerve with two shocks at an interval of 3-5 msec. This is about the interval found between double discharges (Hoff & Grant, 1944) yet the soleus response to the double stimulus did not decline until after the reflexes had decreased.…”

Section: Discussionmentioning

confidence: 74%

The selective effect of procaine on the stretch reflex and tendon jerk of soleus muscle when applied to its nerve

Matthews¹,

Rushworth²

1957

The Journal of Physiology

127

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This paper describes a re-investigation into the mechanism of the selective action of local anaesthetics in paralysing muscle reflexes before affecting muscle power when they are injected into a muscle or applied to nerve. The problem has attracted little interest for the last 25 years, though it has important theoretical and practical implications for the understanding of muscle tone and movement.In 1919, Liljestrand & Magnus showed that the injection of 0 5-1 ml. of 1 % procaine into the triceps muscle of a decerebrate cat almost abolished the rigidity of that muscle without altering its response to stimulation of the brachial plexus or removing reflexes produced by turning the animal's head. Larger doses (4-8 ml.) were required to remove the last traces of tone and these also abolished the response to nerve stimulation, but not the response to direct faradic stimulation of the muscle. The experiments were performed as a preliminary to an investigation of the muscular spasm produced by tetanus toxin, and this was similarly abolished by small doses of procaine in the early stages of poisoning at a time when the spasm could still be removed by dorsal root section. They concluded that the action of procaine was to paralyse the muscle proprioceptor fibres before the motor fibres, as they, like Sherrington (1898), had shown that decerebrate rigidity was largely abolished by dorsal root section.Walshe (1924) used this method of intramuscular procaine injection to analyse the rigidity in patients with paralysis agitans. Appropriately graded injections into biceps or triceps muscles abolished the rigidity in these muscles alone, leaving them 'atonic, flabby and offering no resistance to passive stretch' and without a jerk. Meanwhile, the voluntary power of these muscles was unchanged and the freedom of voluntary movement greatly increased, though the tremor persisted. There were signs of slight ataxia and the injected muscles became 'painless [sic] to deep pressure or pinching'. Similar effects were 16-2

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“…On the other hand, it is noteworthy that a small percentage of soleus axons generate repetitive potentials after, or in some instances, during prolonged 5 to 20 cPS stimulation (Standaert, 1963). The possibility that repetitive potentials occur in muscles responding to voluntary or reflex drive is suggested by the observations of Hoff and Grant (1944) and Denslow (1948) who noted that electromyograms from cat and human postural muscles frequently contain pairs of potentials interspersed among rhythmic 10 to 20 cPs activity. These double potentials resemble P T R muscle potentials in timing and appearance and in the fact that they rarely occur in the gastrocnemius muscle.…”

Section: Discussionmentioning

confidence: 99%

The Mechanisms of Post-Tetanic Potentiation in Cat Soleus and Gastrocnemius Muscles

Standaert

1964

The Journal of General Physiology

104

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Post-tetanic potentiation of muscle contraction strength (PTP) occurs in cat soleus and gastrocnemius muscles. However, the mechanisms of potentiation are different in these two muscles. Soleus PTP is predominantly a neural event. The application of a high frequency stimulus to the soleus nerve regularly causes each subsequent response to a single stimulus to become repetitive. This post-tetanic repetitive activity (PTR) originates in the motor nerve terminal and is transmitted to the muscle. Consequently each potentiated soleus contraction is a brief tetanus. In gastrocnemius PTR occurs too infrequently to account for PTP. Furthermore, PTP occurs in curarized directly stimulated gastrocnemius muscles to the same extent as in the indirectly stimulated muscle. In this instance PTP is a muscle phenomenon.Post-tetanic potentiation (PTP) of muscle contraction seems to be a general phenomenon of neuromuscular systems. It has been observed in almost every muscle in which it has been sought (for review, see Hughes, 1958). Curiously, this ubiquity seems to be a major factor in the failure to provide a satisfactory explanation for the phenomenon. The fact that m a n y muscles respond similarly to a high frequency stimulus has tostered the belief that they share a common mechanism of potentiation, but to date no single mechanism has been found to reconcile the diverse observations.Neurally stimulated cat soleus and gastrocnemius muscles develop PTP of similar appearance. However, examination of the phenomenon in these two muscles revealed two distinct mechanisms of potentiation: one residing in the motor nerve terminal, the other in the muscle. Furthermore, it was found that both mechanisms operate in both muscles, but in different degree. Soleus PTP is predominantly neural, while gastrocnemius PTP is a l m o s t wholly muscular.

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The Supernormal Period in the Recovery Cycle of Motoneurons

Cited by 43 publications

References 0 publications

The behaviour of tonic α and β motoneurones during stimulation of recurrent collaterals

The behaviour of tonic α and β motoneurones during stimulation of recurrent collaterals

The selective effect of procaine on the stretch reflex and tendon jerk of soleus muscle when applied to its nerve

The Mechanisms of Post-Tetanic Potentiation in Cat Soleus and Gastrocnemius Muscles

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