Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Neural Conduction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed1975

Rubrospinal control of static and dynamic fusimotor neurones.

Rubrospinal effects on about 60 extracellularyl recorded gamma-motoneurones were studied in anesthetized cats. All cells were antidromically identified from various muscle nerves. 23 cells were regarded as dynamic as they were activated from a mesencephalic region previously known to influence selectively muscle spindle dynamic sensitivity. The pattern of rubrospinal influence on static fusimotor neurones to different muscles closely followed that previously demonstrated for alpha-motoneurones with pr edominantly excitation of flexor neurones and excitation or inhibition in equal amounts of extensor cells. Dynamic fusimotor neurones were influenced in a strictly reciprocal manner with excitation of flexor cells and inhibition of extensor cells except for a few neurones which could not be reached from nucleur ruber. Evidence was also obtained indicating that the shortest path from nucleus ruber to static fusimotor neurones involves one interneurone.

Animals↗
PubMed1993

Differential projection of the sural nerve to early and late recruited human tibialis anterior motor units: change of recruitment gain.

The effect of a stimulation of the cutaneous sural nerve [three shocks, 2.5 x perception threshold (PT)] was studied on the tibialis anterior (TA) H-reflex and single voluntarily activated TA motor units using post-stimulus time histograms (PSTH). In both cases, when studying only the first recruited motor units, an inhibition with a delay of 10 ms, in relation to the monosynaptic latency of Ia afferents in the common peroneal nerve, was observed. This inhibition had a duration of 10-20 ms. The inhibition was evoked by low-threshold cutaneous fibres, since it could be seen at a stimulation strength close to the perception threshold. The central delay of the inhibition was calculated in two subjects to be 1.8 ms and 1.2 ms respectively. The TA motor units were characterized by their recruitment threshold and minimal firing frequency and the effect of the sural nerve stimulation was subsequently investigated. Early recruited low frequency motor units were found to be inhibited, whereas later recruited motor units with a higher minimal firing frequency were facilitated. Similarly small TA H-reflexes were inhibited, whereas large reflexes were facilitated. This difference in the effect of the sural nerve stimulation was not caused by a difference in the descending command, since the same early recruited motor unit was still inhibited when firing at a high frequency and at a high torque level. Stimulation of the femoral nerve was found to produce a monosynaptic facilitation of the TA H-reflex and a heteronymous monosynaptic peak in the PSTH of single motor units. A stimulation of the sural nerve increased the size of the reflex facilitation, but had no effect on the size of the monosynaptic peak in the PSTH of the single motor units. It is concluded that the effect of the sural nerve stimulation on human TA motor units is similar to observations in the cat and that a similar interneuronal system may be responsible. It is furthermore suggested that the sural nerve stimulation increases the recruitment gain of the TA motoneuronal pool.

Adult↗
PubMed1978

Pulfrich pendulum phenomenon in patients with a history of acute optic neuritis.

The Pulfrich phenomenon is a stereoillusion in which a pendulum swinging at right angles to the line of gaze appears to be describing an elliptical path when absorbing filters are placed in front of one eye. We used two sets of polaroid glasses as adjustable filters. A spot on a modified oscilloscope served at a pendulum bob. Twenty-nine former patients with a history of optic neuritis and visual acuities of greater than or equal to 6/6 in both eyes and twenty-two normal subjects underwent examinations. The patients showed pathological recordings which separated them from the control subjects. The test seems to expose minor residual dysfunction of affected optic nerves where the visual acuity is normalized. This abnormal response when viewing the moving Pulfrich pendulum is probably caused by disturbed neural conduction. The degree of acute visual loss and the time elapsed since the attack did not seem to influence the Pulfrich response. The results may explain why some patients who have recovered from optic neuritis complain of difficulties when viewing moving objects. In addition to the use of Pulfrich illusion test for diagnostic work; i.e. clinical or subclinical attacks of optic neuritis, it can serve as a valuable supplement to the more sophisticated method of visual evoked response.

Acute Disease↗
PubMed1972

Recurrent inhibition of antidromically identified rat supraoptic neurones.

1. In anaesthetized male rats, the hypothalamus and pituitary stalk were exposed by a transpharyngeal approach. The compound field potential of the supraoptic nucleus evoked by stimulation of the pituitary stalk, was recorded with glass electrodes inserted near the origin of the anterior cerebral artery.2. The mean latency of 169 antidromically evoked action potentials isolated from the field was 9.9 msec with an extreme range of 6-26 msec. Although the wave form of the antidromic action potential showed a variety of shapes and sizes and the initial wave could be of either polarity, the majority were strikingly similar in form. The initial wave was positive with an inflexion on the rising phase and was followed by a shallow rather longer lasting negative potential.3. The antidromic nature of the action potential was confirmed when the action potential evoked at constant latency after the stimulus was observed to be cancelled by another occurring spontaneously. Although the antidromic action potentials followed stimulation frequencies greater than 100 Hz, the response to high frequency stimulation was seldom tested since the amplitude of the action potential was greatly reduced at frequencies above 30 Hz if the number of shocks exceeded a critical number, as few as 3-6 at 100 Hz.4. Stimulation of the pituitary stalk at intensities below and near threshold for antidromic invasion of the cell under study was shown by means of post-stimulus time histograms to be associated with an inhibitory period lasting on average 80 msec (S.D. = 13, N = 30).5. An increase in the intensity and duration of the inhibitory period occurred as the intensity of the stimulation was increased as might be expected if the response was mediated synaptically. The inhibitory pathway is believed to involve the recurrent collateral axons already demonstrated anatomically since the stimulation intensities necessary to produce either a marked inhibitory response or antidromic invasion of the cell in question are in most instances nearly the same.

Action Potentials↗