Recovery of Blood-Perfused Mammalian Nerves

Graham, Helen Tredway; Nó, R. Lorente de

doi:10.1152/ajplegacy.1938.123.2.326

Cited by 26 publications

(19 citation statements)

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“…in our experiments, followed by a supernormal period lasting for a further 5 to 15 msec., closely resembles the excitability changes reported for mammalian nerve by Gasser and Grundfest (1936) and by Graham and Lorente de No (1938). The constant presence of a supernormal period in human nerve (also noted by Brown, 1960) is of some interest as there was considerable discussion among earlier workers on the extent to which supernormality might depend upon manipulation of exposed or isolated nerve during animal experiments.…”

Section: Discussionsupporting

confidence: 79%

The refractory and supernormal periods of the human median nerve

Gilliatt¹,

Willison²

1963

Journal of Neurology, Neurosurgery & Psychiatry

137

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While the excitability changes which follow a propagated nerve impulse have been the subject of numerous studies in animals, there have been few references to this subject in man. An attempt to study the refractory period of the human ulnar nerve was made by Wagman and Flick (1951), but as recordings were made from the hypothenar muscles rather than from the nerve itself, the results are difficult to interpret. Krnjevic, Kilpatrick, and Aungle (1955) applied pairs of shocks to the ulnar nerve at the wrist, and investigated the least interval at which a response to the second shock could be recorded from the nerve at the elbow; only two subjects were examined and no estimate of the relative refractory period was made. Brown (1960) also used stimulation of the ulnar nerve at the wrist with recording at the elbow in four subjects, and noted that the recovery of normal responsiveness was followed by transient supernormality.In the present work we have studied the refractory and supernormal periods of the human median nerve with stimulation at the wrist, action potentials being recorded from the nerve above the elbow by a technique similar to that originally described by Dawson and Scott (1949). A briefpreliminaryaccount of this work has been published elsewhere (Gilliatt and Willison, 1962). METHODSFour healthy subjects were used, their ages ranging from 20 to 40 years. Most of the experiments were carried out on two subjects (R.W.G. and R.G.W.) but the main results were confirmed in the other two subjects as well.Before each experiment the subject sat with both arms in hot water to above the elbows for five or 10 minutes. He then lay covered with blankets on a couch, with the arm under examination wrapped in several layers of cotton wool. When these precautions were taken skin temperature, which was measured by a thermistor close to the stimulating cathode, remained above 35°C. throughout experiments lasting up to one hour; no 'Clinical research fellow, M.R.C. experiments are included in the present series in which skin temperature fell below 35°C.Two stimuli of independently variable intensity were delivered through a single cathode over the median nerve at the wrist. The stimulus interval could be varied in 0-1 msec. steps from 0 to 1 I-0 msec. and in 1 msec. steps for intervals longer than this. Each stimulus was a condenser discharge with a rapid rise-time, the decay having a time constant of 60, 100, or 160 psec. Voltage was continuously variable up to 350V. In most of the experiments a time constant of 160 jtsec. was used for both shocks but when small changes in nerve threshold were to be studied, for example, in plotting the supernormal period, a shorter time constant was used for the test shock. In this situation a brief shock had the advantage that a larger voltage range could be used when the physiological change in nerve threshold was small. Both stimuli were delivered through a single isolating transformer (ratio 1: 1) the output impedance being less than 1 kilohm. To allow mixing of stimuli from two...

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Section: Discussionsupporting

confidence: 79%

The refractory and supernormal periods of the human median nerve

Gilliatt¹,

Willison²

1963

Journal of Neurology, Neurosurgery & Psychiatry

137

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“…Increases of 10-20 %, equal to those described in the present paper, have been seen after single action potentials in the lateral giant fibres of the earthworm (Bullock, 1951). Smaller increases after single conditioning shocks have been seen in frog sciatic nerve fibres (Graham, 1934;Bullock, 1951), although there may be no increase at all when sciatic nerves are freshly excised or kept in good condition (Graham & Lorente de N6, 1938). A constancy of conduction velocity to within 1 or 2 % seems to be the rule in most fibres, apart from a brief subnormal period associated with the relative refractory period.…”

Section: The Increased Propagation Velocity After Conditioningsupporting

confidence: 65%

An extreme supernormal period in cerebellar parallel fibres

Gardner-Medwin¹

1972

The Journal of Physiology

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SUMMARY1. The electrical responses produced by stimulation at the surface of the cerebellar cortex have been studied in anaesthetized cats.2. The propagation of the underlying activity is attributed to parallel fibres, but the mode of generation of the potential changes is less certain.3. The threshold for a second response is up to 40 % lower following a conditioning stimulus, and the responses to test stimuli less strong than the conditioning stimulus are correspondingly potentiated.4. A second stimulus given 22 msec after the first produces a response which propagates 15-20 % faster along the folium.5. The reduction of the threshold and the increase of the propagation velocity are as large with small (but above threshold) conditioning shocks as with large shocks.6. Both after-effects are present from 5 to 100 msec after a conditioning stimulus, with maximal values at about 10-30 msec.7. The fibre conduction velocity inferred from collision experiments agrees with that inferred from the propagation velocity of the responses, and shows a similar increase after conditioning.8. A second shock does not recruit a new and faster population of parallel fibres.9. Under the conditions of electrical stimulation the after-effects are probably restricted to those fibres which are active during conditioning.

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“…Detailed studies of excitability changes also showed that under some conditions there can be periods of supernormal excitability (Adrian, 1920), but these were for some time erroneously thought to represent experimental artifacts (Graham and Lorente de No, 1938). Finally, there can be a period of prolonged decrease in excitability, termed the subnormal period.…”

Section: Short-term Dynamics Of Spike Propagationmentioning

confidence: 99%

Beyond faithful conduction: Short-term dynamics, neuromodulation, and long-term regulation of spike propagation in the axon

Bucher¹,

Goaillard²

2011

Progress in Neurobiology

171

190

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Most spiking neurons are divided into functional compartments: a dendritic input region, a soma, a site of action potential initiation, an axon trunk and its collaterals for propagation of action potentials, and distal arborizations and terminals carrying the output synapses. The axon trunk and lower order branches are probably the most neglected and are often assumed to do nothing more than faithfully conducting action potentials. Nevertheless, there are numerous reports of complex membrane properties in non-synaptic axonal regions, owing to the presence of a multitude of different ion channels. Many different types of sodium and potassium channels have been described in axons, as well as calcium transients and hyperpolarization-activated inward currents. The complex time- and voltage-dependence resulting from the properties of ion channels can lead to activity-dependent changes in spike shape and resting potential, affecting the temporal fidelity of spike conduction. Neural coding can be altered by activity-dependent changes in conduction velocity, spike failures, and ectopic spike initiation. This is true under normal physiological conditions, and relevant for a number of neuropathies that lead to abnormal excitability. In addition, a growing number of studies show that the axon trunk can express receptors to glutamate, GABA, acetylcholine or biogenic amines, changing the relative contribution of some channels to axonal excitability and therefore rendering the contribution of this compartment to neural coding conditional on the presence of neuromodulators. Long-term regulatory processes, both during development and in the context of activity-dependent plasticity may also affect axonal properties to an underappreciated extent.

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Recovery of Blood-Perfused Mammalian Nerves

Cited by 26 publications

References 0 publications

The refractory and supernormal periods of the human median nerve

The refractory and supernormal periods of the human median nerve

An extreme supernormal period in cerebellar parallel fibres

Beyond faithful conduction: Short-term dynamics, neuromodulation, and long-term regulation of spike propagation in the axon

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