Latency Conduction Research Articles

Nerve-bundle conduction velocity distribution measurement and transfer function analysis

Human peripheral nerves are composed of thousands of individual nerve fibers whose signal conduction velocities vary from 0.2 to 100 m/s. Though good correlation exist between fiber velocity and the physiological function subserved by these fibers, considerable variation is found for specific end organs (20 to 40 m/s for a single muscle). Though clinical neurophysiologists have routinely measured the maximum conduction velocity of peripheral motor nerves for 30 years, it has not been possible to determine the velocity distributions. This report details a model and noninvasive methodology for motor axon conduction latency distribution mesurement. This distribution, proportional to velocity dispersion, possesses a low-pass filter characteristic which agrees with theoretical predictions and may be significant in some sensory and motor functions.

Axonal conduction latencies of cat retinal ganglion cells.

ArticlesAxonal conduction latencies of cat retinal ganglion cellsD. L. Kirk, B. G. Cleland, and W. R. LevickD. L. Kirk, B. G. Cleland, and W. R. LevickPublished Online:01 Nov 1975https://doi.org/10.1152/jn.1975.38.6.1395MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByVisual latency of ganglion X- and Y-cells: A comparison with geniculate X- and Y-cellsVision Research, Vol. 27, No. 9Parallel visual pathways: A reviewVision Research, Vol. 20, No. 7 More from this issue > Volume 38Issue 6November 1975Pages 1395-1402 Copyright & PermissionsCopyright © 1975 the American Physiological Societyhttps://doi.org/10.1152/jn.1975.38.6.1395PubMed1221078History Published online 1 November 1975 Published in print 1 November 1975 Metrics

Axonal conduction velocity and perikaryal size

The recent identification of brisk-transient units with alpha cells in the cat's retina provided a direct opportunity to test the widely held belief that larger cells give rise to larger axons, and smaller to smaller. Alpha-cell perikarya increase substantially in size over the first 2 mm from the center of the area centralis. In one cat a map was obtained of the receptivefield centers of all brisk-transient units in the region of the area centralis together with their antidromic latencies to optic tract stimulation. The map was then brought into approximate register with a map of all the alpha cells of the region. The correspondence was controlled by the placement and subsequent identification of electrolytic lesions. Thus perikaryal size could be rather directly compared with axonal conduction latency. The expected relation was verified under singularly uniform circumstances.

Axonal conduction latencies of cat retinal ganglion cells in central and peripheral retina.

The axonal conduction latency of brisk-sustained and brisk-transient cat retinal ganglion cells increases with proximity to the area centralis. The trend is gradual with considerable local scatter of latencies, and is similar for cells with crossed and uncrossed axons.

Conduction in descending spinal pathways initiated by somatosympathetic reflexes.

In anesthetized, paralyzed cats, the effects of stimulation at the dorsolateral sulcus (DLS) of the spinal cord at the C8 segment were recorded from the T2 white ramus. Stimulation of the DLS at the C8 segment produced evoked responses which had average conduction latencies of 13.3, 25.8, and 43.4 ms and were designated as the early, intermediate, and late response, respectively. Intermediate and late evoked responses were also recorded when the contralateral funiculus, the third or late evoked response was abolished or greatly attenuated, but the intermediate response was still observed although it was diminished in amplitude. The early evoked response was usually observed with stimulation at the ipsilateral C8 segment following placement of the lesion. These data suggest that afferent impulses, which ascend to supraspinal segments of the central nervous system, are transmitted to preganglionic neurons of the sympathetic nervous system through descending pathways in the dorsolateral funiculus of the spinal cord. Stimulation of afferent fibers on the ipsilateral or contralateral side of the spinal cord produces volleys which ascend unilaterally and descend bilaterally to preganglionic neurons. The pathways producing the intermediate evoked response, which was still observed after an ipsilateral lesion was made in the spinal cord, may include both the ascending pathway and other connections with the preganglionic neurons.

Motor nerve conduction in 47, XXY and 48, XXYY males, and 47, XXX and 45, X females.

Measurements were made of the maximum motor nerve conduction in the median and ulnar nerves of the right forearm for the four sex chromosomally abnormal groups 47, XXY and 48, XXYY males, 47, XXX and 45, X females. The results obtained were compared with male and female control groups (a) from the general population and (b) from a subnormality hospital. No significant differences were detected between the corresponding results for 47, XXY males and subnormal males. The results for the 47, XXY males were different from those for normal and subnormal females, except in the case of motor conduction in the median nerve for the subnormal female group. There is a suggestion of marked differences in motor conduction and distal latency in 48, XXYY males when compared to the two male control groups. 47, XXX females showed significant differences in motor conduction and distal latency when compared to normal females, but not when compared to subnormal females. No significant differences were detected between 45, X females and normal females for any of the variables measured.

Effect of overwork during reinnervation of rat muscle

Changes in muscle weights, protein content, and conduction latencies to gastrocnemius along with muscle weights of soleus and plantaris were investigated in adult rats at 72 hr, 1, 2, 3, 4, and 6 wk after bilateral sciatic nerve crush. The effect of overwork (induced by tenotomy of synergistic muscles) initiated in pre- and postreinnervation periods was evaluated in soleus and plantaris muscles. Evoked potentials by nerve conduction were lost at 72 hr and reappeared at the end of 3 wk. Muscle weight and protein content in the gastrocnemius decreased from 72 hr until 2 wk postdenervation. Muscle weights of plantaris and soleus followed the same trend. From 3 to 6 wk postdenervation all three muscles gained in weight and the protein content of gastrocnemius continued to increase to normal accompanied by shortened latency to indirect stimulation, although the latter returned only to 75% of normal. The return of nerve conduction 3 wk after neuronal damage indicates that functional reinnervation takes place between 2 and 3 wk after the nerve crush. The overwork, induced in the soleus and plantaris muscles by elimination of synergists, at 2 wk (Group II) and 3 wk (Group I) after denervation, showed contrasting results in protein content. Overwork in Group I significantly increased muscle weight, absolute amount of sarcoplasmic, myofibrillar and stromal proteins, and fiber diameters in both soleus and plantaris. Muscle weight, sarcoplasmic protein, and myofibrillar protein decreased in both muscles of Group II. However, fiber diameter exceeded control values only in the plantaris and was associated with an increased number of fibers exhibiting low myosin ATPase (pH 9.4) activity. The results of this study suggest that overwork begun within the period of reinnervation may be more beneficial than when initiated before this event.

Bilateral pathology in Bell??s palsy

The uninvolved side of the face of 18 patients with Bell's palsy was studied with electromyography and nerve conduction latency determinations. Fourteen patients demonstrated evidence of subclinical neuropathy. In the majority, the lesion appeared to be neuropractic. It is speculated that this may be one factor responsible for difficulty in utilizing studies comparing the two sides of the face to prognosticate the outcome of Bell's palsy.

Bilateral pathology in Bell's palsy.

The "uninvolved" side of the face of 18 patients with Bell's palsy was studied with electromyography and nerve conduction latency determinations. Fourteen patients demonstrated evidence of subclinical neuropathy. In the majority, the lesion appeared to be neuropractic. It is speculated that this may be one factor responsible for difficulty in utilizing studies comparing the two sides of the face to prognosticate the outcome of Bell's palsy.

Role of Electro-Diagnostic Tests In Early Detection of Diabetic Neuropathy

Since the peripheral nerve has the ability to regenerate, therapeutic intervention at earlier stages expected to have a better result in the treatment of diabetic neuropathy. So early detection of diabetic neuropathy is one of the major goals in its management. Purpose: The purpose of present study is to evaluate the efficacy of the electrodiagnostic tests to detect diabetic neuropathy at an early stage (before development of the signs of neuropathy). Method: 30 diabetic patients with or without symptoms of diabetic neuropathy were included in the test group. Diabetic patients with signs of neuropathy and with other complications, like stroke, peripheral vascular diseases were excluded. Twenty six control subjects (non-diabetic with no family history of diabetes) were included. Both the groups were matched for age. To see the functional status of peripheral nerves motor nerve conduction velocity (NCV), compound muscle action potentials (CAMP) of median nerve were studied. Sensory nerve conduction velocities (NCV), and sensory nerve action potential (SNAP) of median and sural nerves were also measured. Results: Sensory nerve conduction velocity of sural nerve was significantly slowed (43.84±8.23 vs 48.23±5.03 m/sec, p < .05) in diabetic patients. Sural sensory nerve action potential has lower in amplitude (13.31±7.03 vs 14.24±4.714 mv, p<.3) in diabetic patients. Median sensory nerve conduction velocity did show difference (50.89+8.23 vs 57.17±6.67 m/s, p < .01) and median sensory nerve action potential has significantly lower in amplitude (3.86±1.016 vs 7.39±4.79, p < .001) in diabetic patients. No significant difference was found in median nerve motor conduction velocity between the two groups of subjects. Amplitude of compound muscle action potential of median nerve also shows no significant variations.Considering mean±SD value of conduction parameter as the cut off value, sural nerve sensory conduction velocity was found slowed in 8 diabetic subjects (26%). Sural nerve sensory action potential was of lower amplitude in 12 diabetic subjects (40%). Eleven diabetic subjects (36%) had lower amplitude for median sensory nerve action potential (SNAP). For compound muscle action potential (CAMP) and sensory nerve action potential (SNAP) half the mean value of control was the cut off point. Conclusion: The result suggests that in diabetic patients of Bangladesh with or without symptoms of neuropathy, abnormalities of nerve conduction parameters can be detected early by routine electrodiagnostic monitoring. Sensory nerve conduction parameters are affected more than motor ones. Amplitude abnormalities are slightly more common than conduction velocity or latency abnormalities for sensory studies. Lower extremity nerves were affected more. Sural median nerve has the highest abnormalities in diabetic patients with early neuropathy. DOI: http://dx.doi.org/10.3329/bjn.v24i1.3038 Bangladesh Journal of Neuroscience 2008; Vol. 24 (1) :34-44

Functional differentiation of hypoglossal neurons in cats.

In decerebrate and unanesthetized cats, changes in the intracellular potential of neurons in the hypoglossal nucleus following stimulation of the hypoglossal nerve were recorded.1. Of 158 cells examined, motoneurons (94.3%), interneurons (5.7%) were distinguished by hypoglossal nerve stimulation.2. Two groups of motoneurons responded differently in critical frequency for SD and/or IS blocking to the antidromic stimulation.3. Sizes of the motor axons were estimated from the conduction distance and latency of antidromic invasion to each motoneuron. The diameter distribution revealed gross unimodal configuration with the peak between 3 and 5μ.4. Some of the characters of the potential change in the “respiratory” hypoglossal motoneurons and slow fluctuations of various rhythm in others were reported.

Intersensory differences in the effect of warning signals on reaction time

A visual signal with two equiprobable alternative values, calling for a manual choice response, was presented to the subject after a fairly long (5 sec) waiting period from the ‘start’ signal. The effect of introducing a warning signal at a fixed interval between 0 and 500 msec prior to the visual signal to respond was examined. When the warning signal was presented in the auditory modality, it was found that simultaneous presentation of the auditory signal improved reaction times to the visual signal and that a further improvement developed as the interval was increased to 200 msec. When the warning signal was presented visually no improvement in reaction times to the visual signal to respond was found until the interval reached 150 msec. The results from the auditory warning condition may be accounted for by the difference in conduction latencies of simultaneously presented auditory and visual signals. The results from the visual warning condition suggest that no use can be made of a warning signal entering by the same modality as the signal to respond until an interval of 100–150 msec has elapsed.

Electrodiagnostic Studies in Facial Paralysis

ELECTRONIC instruments have become well accepted tools in the diagnosis of medical illness. For years electrocardiographic and electroencephalographic techniques have proved extremely helpful in the evaluation of cardiac and central nervous system function. More recently, electrodiagnostic studies of peripheral motor nerve function have gained widespread acceptance. It is the purpose of this paper to review the current electrodiagnostic methods that are useful in evaluating patients with facial paralysis, to indicate what some of the correlates are with respect to the patient's disease process and the electrodiagnostic findings, and to present an analysis of 24 patients. Electrodiagnostic Methods At present, the two electrodiagnostic methods used to assess facial nerve function are nerve stimulation and electromyography. Each of these methods provides valuable information when used in the proper manner and at the proper time (Fig 1). Nerve stimulation techniques are of three types: (1) nerve excitability tests, (2) conduction latency measurements, and

Ver�nderungen von Leitungsgeschwindigkeit und Latenz am Papillarmuskel der Katze w�hrend des Refrakt�rstadiums

Measurements of conduction velocity and latency were performed on papillary muscles of cats during the refractory period using the micro-electrode technique. The action potentials were recorded from two micro-electrodes and the time interval between the main and the test stimuli was gradually shortened. A high sweep speed was used and the sweeps were triggered by the main and test stimuli. The following results could be obtained:

Ulnar nerve conduction velocity and H-reflex in infants and children.

Measurements of conduction velocity of the motor fibers of the ulnar nerve in the segment between the upper part of the arm and the wrist were made in 6 premature infants, 42 full-term newborn infants and 98 children up through the age of 14 years. In premature infants, 21 – 40 days before full term, values ranged from 18 to 22 meters per second with a mean of 21. Full-term newborn infants had velocities that ranged from 21 to 33 m.p.s., with a mean of 28. The values in the newborn were about one-half those of normal young adults, which range from 47 to 73 m.p.s. (mean, 60). By the age of 3 years almost all values were in the lower part of the adult range and, at 5 years, the velocities were not significantly different from those of the adult. These observations are in harmony with information about the diameter of nerve fibers during growth in man. The H-reflex could be elicited by stimulation of the ulnar nerve in almost every newborn infant. By the age of 1 year and thereafter it could rarely be elicited. Between the elbow and wrist, afferent fibers subserving this reflex conducted with a mean velocity of 30 m.p.s. Data on the action potential of the hypothenar muscles, residual latency of conduction in the ulnar nerve, latency of the H-reflex and conduction in the peroneal nerve in infants and children are compared with those on adults. Submitted on July 15, 1959

ON THE TIME RELATIONS OF THE KNEE‐JERK AND SIMPLE REFLEXES

A diphasic action current is recorded by means of the string galvanometer from the quadriceps muscle when the knee‐jerk is elicited.Its latency is about half as long as that of the electrical variation accompanying action of the muscles in the homonymous flexion reflex of the hind limb.The latency of the heteronymous extension reflex is about one‐thousandth of a second longer than that of the homonymous reflex.An electrical variation, consisting in a diminution of the demarcation current, is observed in the cut anterior crural (femoral) nerve when the skin on the dorsum pedis or mesial aspect of the thigh is mechanically stimulated. A similar electrical variation with shorter latent period is obtained in the same nerve when the knee‐jerk is elicited. By means of these variations the latency of afferent nerve endings can be determined, after deducting nerve conduction time from the latency of the variation.The synapse time in the case of the knee‐jerk and the other reflexes is obtained by deducting from the latency of the action current of the muscles reflexly excited periods attributable to (1) the afferent endings, (2) nerve conduction, and (3) motor endings and latency of action current.The action currents accompanying knee‐jerk and flexion reflex may in some cases be detected in the same recorded curve.The synapse time of the knee‐jerk in the spinal cat is about two‐thousandths of a second, of the homonymous flexion reflex about four‐thousandths.The relation between the synapse times suggests that the knee‐jerk mechanism involves one spinal synapse or set of synapses, while the flexion reflex involves two.