Influence of unit distance and conduction velocity on the spectra of extracellular action potentials recorded with intrafascicular electrodes

2013 ◽  
Vol 35 (1) ◽  
pp. 116-124 ◽  
Author(s):  
Shaoyu Qiao ◽  
Ken Yoshida
Keyword(s):  
Conduction Velocity ◽  
Action Potentials ◽  
Unit Distance ◽  
Intrafascicular Electrodes

Electronmicroscopic and electrophysiological studies of the teat branch of the XIII thoracic nerve: relationship with lactation in the rat

1988 ◽  
Vol 118 (3) ◽  
pp. 471-483 ◽  
Author(s):  
L. M. Voloschin ◽  
E. Décima ◽  
J. H. Tramezzani
Keyword(s):  
Electrical Stimulation ◽  
Conduction Velocity ◽  
Action Potentials ◽  
Silent Period ◽  
High Amplitude ◽  
Milk Ejection ◽  
Nerve Activity ◽  
Thoracic Nerve ◽  
Myelinated Fibres ◽  
Stimulation Of

ABSTRACT Electrical stimulation of the XIII thoracic nerve (the 'mammary nerve') causes milk ejection and the release of prolactin and other hormones. We have analysed the route of the suckling stimulus at the level of different subgroups of fibres of the teat branch of the XIII thoracic nerve (TBTN), which innervates the nipple and surrounding skin, and assessed the micromorphology of the TBTN in relation to lactation. There were 844 ± 63 and 868 ± 141 (s.e.m.) nerve fibres in the TBTN (85% non-myelinated) in virgin and lactating rats respectively. Non-myelinated fibres were enlarged in lactating rats; the modal value being 0·3–0·4 μm2 for virgin and 0·4–0·5 μm2 for lactating rats (P > 0·001; Kolmogorov–Smirnov test). The modal value for myelinated fibres was 3–6 μm2 in both groups. The compound action potential of the TBTN in response to electrical stimulation showed two early volleys produced by the Aα- and Aδ-subgroups of myelinated fibres (conduction velocity rate of 60 and 14 m/s respectively), and a late third volley originated in non-myelinated fibres ('C') group; conduction velocity rate 1·4 m/s). Before milk ejection the suckling pups caused 'double bursts' of fibre activity in the Aδ fibres of the TBTN. Each 'double burst' consisted of low amplitude action potentials and comprised two multiple discharges (33–37 ms each) separated by a silent period of around 35 ms. The 'double bursts' occurred at a frequency of 3–4/s, were triggered by the stimulation of the nipple and were related to fast cheek movements visible only by watching the pups closely. In contrast, the Aα fibres of the TBTN showed brief bursts of high amplitude potentials before milk ejection. These were triggered by the stimulation of cutaneous receptors during gross slow sucking motions of the pup (jaw movements). Immediately before the triggering of milk ejection the mother was always asleep and a low nerve activity was recorded in the TBTN at this time. When reflex milk ejection occurred, the mother woke and a brisk increase in nerve activity was detected; this decreased when milk ejection was accomplished. In conscious rats the double-burst type of discharges in Aδ fibres was not observed, possibly because this activity cannot be detected by the recording methods currently employed in conscious animals. During milk ejection, action potentials of high amplitude were conveyed in the Aα fibres of the TBTN. During the treading time of the stretch reaction (SR), a brisk increase in activity occurred in larger fibres; during the stretching periods of the SR a burst-type discharge was again observed in slow-conducting afferents; when the pups changed nipple an abrupt increase in activity occurred in larger fibres. In summary, the non-myelinated fibres of the TBTN are increased in diameter during lactation, and the pattern of suckling-evoked nerve activity in myelinated fibres showed that (a) the double burst of Aδ fibres, produced by individual sucks before milk ejection, could be one of the conditions required for the triggering of the reflex, and (b) the nerve activity displayed during milk-ejection action may result, at least in part, from 'non-specific' stimulation of cutaneous receptors. J. Endocr. (1988) 118, 471–483

scholarly journals Conduction velocity of the rabbit facial nerve: a noninvasive functional evaluation

2003 ◽  
Vol 17 (2) ◽  
pp. 126-131 ◽  
Author(s):  
Belmiro Cavalcanti do Egito Vasconcelos ◽  
Cosme Gay Escoda ◽  
Ricardo José de Holanda Vasconcellos ◽  
Riedel Frota Sá Nogueira Neves
Keyword(s):  
Facial Nerve ◽  
Conduction Velocity ◽  
Nerve Conduction ◽  
Action Potentials ◽  
Functional Evaluation ◽  
Surface Electrodes ◽  
Nerve Grafts ◽  
Synthetic Materials ◽  
Facial Nerves ◽  
The Mean

The aim of this study was to evaluate standardized conduction velocity data for uninjured facial nerve and facial nerve repaired with autologous graft nerves and synthetic materials. An evaluation was made measuring the preoperative differences in the facial nerve conduction velocities on either side, and ascertaining the existence of a positive correlation between facial nerve conduction velocity and the number of axons regenerated postoperatively. In 17 rabbits, bilateral facial nerve motor action potentials were recorded pre- and postoperatively. The stimulation surface electrodes were placed on the auricular pavilion (facial nerve trunk) and the recording surface electrodes were placed on the quadratus labii inferior muscle. The facial nerves were isolated, transected and separated 10 mm apart. The gap between the two nerve ends was repaired with autologous nerve grafts and PTFE-e (polytetrafluoroethylene) or collagen tubes. The mean of maximal conduction velocity of the facial nerve was 41.10 m/s. After 15 days no nerve conduction was evoked in the evaluated group. For the period of 2 and 4 months the mean conduction velocity was approximately 50% of the normal value in the subgroups assessed. A significant correlation was observed between the conduction velocity and the number of regenerated axons. Noninvasive functional evaluation with surface electrodes can be useful for stimulating and recording muscle action potentials and for assessing the functional state of the facial nerve.

The Ionic Basis of the Fast Action Potentials in the Isolated CerebroVisceral Connective of Anodonta Cygnea

1969 ◽  
Vol 51 (2) ◽  
pp. 297-318
Author(s):  
ALBERT D. CARLSON ◽  
J. E. TREHERNE
Keyword(s):  
Conduction Velocity ◽  
Action Potentials ◽  
Electrolyte Solutions ◽  
Monovalent Cations ◽  
Bathing Medium ◽  
Anodonta Cygnea ◽  
Sodium Dependent ◽  
Ionic Basis

1. The large axons in the cerebro-visceral connective have been shown to function for appreciable periods in preparations bathed in sodium-free non-electrolyte solutions. 2. The results of experiments on the effects of organic monovalent cations and anions, together with observations on the effects of tetrodotoxin, procaine and manganous ions and the changes in conduction velocity in tris chloride and dextran solutions indicate that the action potentials are, nevertheless, mediated by conventional sodium-dependent mechanisms. 3. Radioisotope experiments show that there is a small fraction, of approx. 0.5 mM/kg. tissue, which does not exchange rapidly with the 22Na in the bathing medium and which can be depleted by stimulation in sodium-free solutions. 4. On the basis of these observations it is suggested that there is sequestered extra-axonal sodium fraction which can be utilized by the large axons to maintain action potentials in preparations bathed in sodium-free solutions.

Activity-Dependent Modulation of Axonal Excitability in Unmyelinated Peripheral Rat Nerve Fibers by the 5-HT(3) Serotonin Receptor

2006 ◽  
Vol 96 (6) ◽  
pp. 2963-2971 ◽  
Author(s):  
Philip M. Lang ◽  
Gila Moalem-Taylor ◽  
David J. Tracey ◽  
Hugh Bostock ◽  
Peter Grafe
Keyword(s):  
Action Potential ◽  
Conduction Velocity ◽  
Action Potentials ◽  
Serotonin Receptor ◽  
Nerve Fibers ◽  
Nerve Trunk ◽  
Axonal Membrane ◽  
Membrane Hyperpolarization ◽  
Axonal Excitability ◽  
Activity Dependent

Activity-dependent fluctuations in axonal excitability and changes in interspike intervals modify the conduction of trains of action potentials in unmyelinated peripheral nerve fibers. During inflammation of a nerve trunk, long stretches of axons are exposed to inflammatory mediators such as 5-hydroxytryptamine [5-HT]. In the present study, we have tested the effects of m-chlorophenylbiguanide (mCPBG), an agonist at the 5-HT(3) serotonin receptor, on activity- and potential-dependent variations in membrane threshold and conduction velocity of unmyelinated C-fiber axons of isolated rat sural nerve segments. The increase in axonal excitability during application of mCPBG was much stronger at higher frequencies of action potentials and/or during axonal membrane hyperpolarization. The effects on the postspike recovery cycle also depended on the rate of stimulation. At an action potential frequency of 1 Hz or in hyperpolarized axons, mCPBG produced a loss of superexcitability. In contrast, at 0.33 Hz, a small increase in the postspike subexcitability was observed. Similar effects on excitability changes were found when latency instead of threshold was recorded, but only at higher action potential frequencies: at 1.8 Hz, mCPBG increased conduction velocity and reduced postspike supernormality. The latter effect would increase the interspike interval if pairs of action potentials were conducted along several cm in an inflamed nerve trunk. These data indicate that activation of axonal 5-HT(3) receptors not only enhances membrane excitability but also modulates action potential trains in unmyelinated, including nociceptive, nerve fibers at high impulse rates.

Strength-duration and activity-dependent excitability properties of frog afferent axons and their intraspinal projections

1991 ◽  
Vol 65 (3) ◽  
pp. 468-476 ◽  
Author(s):  
N. C. Tkacs ◽  
R. D. Wurster
Keyword(s):  
Conduction Velocity ◽  
Action Potentials ◽  
Conditioning Stimulus ◽  
Membrane Properties ◽  
Stimulation Site ◽  
Antidromic Activation ◽  
Entry Zone ◽  
Activity Dependent ◽  
Fiber Action

1. Excitability properties of afferent axons and terminal regions in frog dorsal roots (DR) and spinal cords in vitro were investigated by antidromic activation from three sites--the root, the entry zone (dorsal white matter or DW), and deep within the dorsal horn (DH)--while recordings were made from the DR. 2. Two approaches were used to assess physiological differences between telodendria and trunk axons. Rheobases and strength-duration time constants (tau sd) of single DR fibers were measured by stimulation in the DH or in the DW. Conduction velocity was estimated on the basis of onset latencies of evoked spikes (the time from stimulation to action potential arrival at the recording electrodes). Population supernormality was evaluated on the basis of responses to conditioned and unconditioned submaximal stimuli delivered to the DH or to the proximal end of isolated DRs. 3. Single-fiber action potentials occurred at longer latencies after DH stimulation than after DW stimulation. Estimated intraspinal conduction velocity was congruent to 0.6 m/s. Extraspinal conduction velocity in these fibers averaged 22.2 m/s. Average tau sd was longer in the DH than in the DW (670 microseconds vs. 204 microseconds). 4. DH and DR test responses evoked 10-150 ms after a conditioning stimulus had increased areas relative to unconditioned test responses. Conditioning-associated changes in evoked responses were greater with the DH stimulation site than with the DR stimulation site, and these changes were not altered by treatment designed to block synaptic transmission. 5. We conclude that membrane properties determining tau sd differ between large afferent axons and fine terminal regions of those axons.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Mapping axon conduction delays in vivo from microstructural MRI

2018 ◽  
Author(s):  
Mark Drakesmith ◽  
Derek K Jones
Keyword(s):  
Conduction Velocity ◽  
Action Potentials ◽  
Volume Fraction ◽  
Relative Sensitivity ◽  
Significant Advance ◽  
Relaxation Processes ◽  
Neural Communication ◽  
Axonal Density ◽  
G Ratio

AbstractThe conduction velocity (CV) of action potentials along axons is a key neurophysiological property central to neural communication. The ability to estimate CV in humans in vivo from non-invasive MRI methods would therefore represent a significant advance in neuroscience. However, there are 2 major challenges that this paper aims to address: (1) much of the complexity of the neurophysiology of action potentials cannot be captured with currently available MRI techniques. Therefore, we seek to establish the variability in CV that can be captured when predicting CV purely from parameters that can be estimated from MRI (axon diameter and g-ratio); and (2) errors inherent in existing MRI-based biophysical models of tissue will propagate through to estimates of CV, the extent to which is currently unknown.Issue (1) is investigated by performing a sensitivity analysis on a comprehensive model of axon electrophysiology and determining the relative sensitivity to various morphological and electrical parameters.The investigations suggest that 89.2 % of the variance in CV is accounted for by variation in AD and g-ratio. The observed dependency of CV on AD and g-ratio is well characterised by a previously reported model by Rushton.Issue (2) is investigated through simulation of diffusion and relaxometry MRI data for a range of axon morphologies, applying models of restricted diffusion and relaxation processes to derive estimates of axon volume fraction (AVF), AD and g-ratio and estimating CV from the derived parameters. The results show that errors in the AVF have the biggest detrimental impact on estimates of CV, particularly for sparse fibre populations (AVF< 0.3). CV estimates are most accurate (below 5% error) where AVF is above 0.3, g-ratio is between 0.6 and 0.85 and AD is below 10 µm. Fortunately, these parameter bounds are typically satisfied by most myelinated axons.In conclusion, we demonstrate that accurate CV estimates can be inferred in axon populations across a range of configurations, except in some exceptional cases or where axonal density is low. As a proof of concept, for the first time, we generated an in vivo map of conduction velocity in the human corpus callosum with estimates consistent with values previously reported from invasive electrophysiology in primates.

Effects of Na and Ca on the generation and conduction of excitation in the ureter

1965 ◽  
Vol 208 (4) ◽  
pp. 715-719 ◽  
Author(s):  
Makoto Kobayashi
Keyword(s):  
Conduction Velocity ◽  
Renal Pelvis ◽  
Action Potentials ◽  
Conduction Block ◽  
Krebs Solution ◽  
Taenia Coli ◽  
Free Solution ◽  
The Difference ◽  
Conduction Of Excitation ◽  
Normal Ringer

Effects of Na+ and Ca++ on the generation and the conduction of excitation were studied by using a pelvis ureter specimen of cat. Action potentials were recorded simultaneously from the renal pelvis and the various regions of the ureter, and they were used to indicate the arrival of excitation. In Na+-deficient solutions, both the frequency of excitation and the conduction velocity decreased gradually, and finally a conduction block occurred at the border between the renal pelvis and ureter. In Na+-free solution spontaneous excitation was not observed in most cases. When excess Ca++ was added to Na+-free solution, spontaneous excitation was restored, but the concentration of Ca++ necessary for the restoration had to be at least twice that in normal Ringer-Krebs solution. The difference between the ureter and taenia coli was considered with regard to the role that Na+ and Ca++ play in the generation of spontaneous excitation.

scholarly journals Limb-Specific Features and Asymmetry of Nerve Conduction Velocity and Nerve Trunk Size in Human

2020 ◽  
Vol 11 ◽  
Author(s):  
Ayaka Nobue ◽  
Yoko Kunimasa ◽  
Hiromu Tsuneishi ◽  
Kanae Sano ◽  
Hiroyuki Oda ◽  
...  
Keyword(s):  
Conduction Velocity ◽  
Nerve Conduction ◽  
Action Potentials ◽  
Electric Stimulation ◽  
Nerve Conduction Velocity ◽  
Lower Limbs ◽  
Upper Limbs ◽  
Cross Sectional ◽  
Nerve Ultrasonography ◽  
Human Nerve

This study aimed to simultaneously examine the differences of human nerve conduction velocity (NCV) and nerve cross-sectional area (nCSA) between the upper and lower limbs and between different regions of the upper and lower limbs. Thirty healthy subjects volunteered for the study. NCV and nCSA of the ulnar and tibial nerves were measured with the dominant and non-dominant arms and the supporting and reacting legs using supramaximal electric stimulation and peripheral nerve ultrasonography at three regions for ulnar and tibial nerves, respectively. Supramaximal electric stimulation was superficially applied to the ulnar and tibial nerves at each point. These action potentials were recorded from the digiti minimi and soleus muscles for the ulnar and tibial nerves, respectively. Our results clearly showed that the NCV, nCSA, and circumference of the ulnar and tibial nerves were higher and greater in the lower limbs than in the upper limbs. The greater the circumference, the greater the nCSA for both the upper and lower limbs. However, unlike the upper limbs, the supporting leg did not have higher NCV than the reacting leg despite its greater circumference. Therefore, nCSA can be related to the circumference but not necessarily function for NCV developments of the lower limbs. These various aspects between the upper and lower limbs suggest that NCV does not depend on the nCSA sizes or upper and lower limb circumference; the results indicate the existence of limb-specific NCV but not nCSA developments.

The Ionic Basis of Axonal Conduction in the Central Nervous System of Viviparus Contectus (Millet) (Gastropoda: Prosobranchia)

1972 ◽  
Vol 57 (1) ◽  
pp. 41-53
Author(s):  
D. B. SATTELLE
Keyword(s):  
Action Potential ◽  
Conduction Velocity ◽  
Action Potentials ◽  
Slow Component ◽  
Choline Chloride ◽  
Slight Reduction ◽  
Action Current ◽  
Sodium Dependent ◽  
Dependent Mechanism ◽  
Normal Ringer

1. The compound action potential recorded from the pleural-supraintestinal connective of Viviparus contectus consists of a large, slow component with an average conduction velocity of about 0.02 m/sec (at 23° C) and a faster component with a conduction velocity of 0.10 m/sec (at 23° C) for the fastest fibres. 2. Both fast and slow action potentials are rapidly abolished by the substitution of tris chloride and choline chloride for the sodium salts of normal Ringer. Tetrodotoxin, applied at 10-5M rapidly abolishes action potentials in all fibres. It is, therefore, concluded that a largely sodium-dependent mechanism of spike generation operates in all axons of the connective. 3. Lithium ions effectively substitute for sodium ions in maintaining the fast action potentials for extended periods, whereas tetraethylammonium ions do not. 4. When the calcium chloride of normal Ringer is replaced by sucrose, magnesium chloride or barium chloride, conduction of fast action potentials is maintained. A small increase in the sensitivity of all axons to tetrodotoxin is observed in calcium-free Ringer; a slight reduction in the spike amplitude of fast action potentials follows the application of manganous ions at 5 mM/l in normal Ringer. It is concluded that any possible contribution of calcium to the generation of the action current of the fast action potential is very small compared to that of sodium. 5. All axons of the connective function for extended periods in sodium-free (dextran) Ringer. Under these conditions, tetrodotoxin blocks conduction in all fibres at concentrations of 10-6M, suggesting that function in dextran Ringer is maintained by a sodium-dependent mechanism.

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