ON THE EFFECTS OF POLARIZATION OF NERVE FIBERS BY EXTRINSIC ACTION POTENTIALS

1932 ◽  
Vol 101 (3) ◽  
pp. 559-564 ◽  
Author(s):  
E. A. Blair ◽  
Joseph Erlanger
Keyword(s):  
Action Potentials ◽  
Nerve Fibers

scholarly journals Effects of Munari powder on physical and sensory-motor parameters: a preliminary report

2015 ◽  
Vol 25 (2) ◽  
pp. 191
Author(s):  
Nejc Sarabon
Keyword(s):  
Action Potentials ◽  
Pain Threshold ◽  
Mechanical Stimulus ◽  
Nerve Fibers ◽  
Short Report ◽  
Balance Test ◽  
Patch Application ◽  
Sitting Balance ◽  
Sensory Motor ◽  
Trunk Extension

Munari powder is broadly used in physical medicine and rehabilitation to decrease pain and help normalize sensory-motor function. It operates as TPRV1 agonist and “stops” generation of action potentials in pain nerve fibers. This is a short report of a pilot study on 20 subjects. Every subject underwent four visits to our laboratory, where the Munari applications and related measurements of its effects took place. Each of the healthy adults received the following applications: (1) placebo, i.e. 0% cayenne pepper mixture, consisting only of water and kaolin, (2) weak, i.e. 2.5% cayenne pepper mixture, (3) medium, i.e. 5.0% cayenne pepper mixture, and (4) strong, i.e. 10% cayenne pepper mixture. The assessments were carried out before the Munari powder patch application, right after the application, and 15 and 30 min after the termination of the 20-minute Munari powder patch application. We measured subjective cold/hot feeling on visual analogue scale, blood pressure, body temperature, skin light touch sensations, sense for two-point discrimination, and pain threshold to the mechanical stimulus. Besides these tests, maximal voluntary force during isometric trunk extension and the sitting balance test were performed. The preliminary results indicate that the 5% concentration of cayenne pepper mixture is the best choice because no additional effects were observed with the 10% concentration and the effects are higher than with 2.5% concentration. Whether this will be also thrue for the patients suffering pain ought to be determined.

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.

An intracellular study of chemosensory fibers and endings

1980 ◽  
Vol 44 (6) ◽  
pp. 1077-1088 ◽  
Author(s):  
Y. Hayashida ◽  
H. Koyano ◽  
C. Eyzaguirre
Keyword(s):  
Carotid Body ◽  
Action Potentials ◽  
Physiological Saline ◽  
Mean Amplitude ◽  
Nerve Fibers ◽  
Chemical Stimulation ◽  
Nerve Terminals ◽  
Generator Potential ◽  
Single Nerve ◽  
Frequency Changes

1. The carotid body and its nerve, removed from anesthetized cats, were placed in physiological saline flowing under paraffin oil. The nerve, lifted into the oil, was used for either electrical stimulation or recording of the total afferent discharge. Intracellular recordings were obtained from individual nerve fibers and endings within the carotid body. The recording sites were identified by injecting Procion yellow through the intracellular electrodes; the tissues were then prepared for histology and observed with episcopic fluorescence or Nomarski optics. 2. Intracellularly recorded chemosensory fibers conducted at 1.1-30 m/s and usually displayed action potentials of regular amplitude. At times, however, some spikes become partially blocked while others maintained their original amplitude. "Natural" (hypoxia) or chemical (ACh or NaCN) stimulation induced different patterns of frequency changes of the large and small action potentials. This indicated nerve fiber branching at some distance from the recording site. 3. Intra- and extracellularly recorded spikes were blocked in 0 [Na+]0 by tetrodotoxin (TTX) or procaine. 4. During chemical stimulation, a slowly occurring depolarization (receptor or generator potential) was recorded intracellularly from the afferent fibers. It developed concomitantly with the increase in discharge. 5. Impalement of single nerve terminals (histologically identified) showed numerous "spontaneous" depolarizing potentials (SDPs) that had a mean amplitude of 5.6 mV, a mean duration of 46.1 ms, and nearly random distribution. They increased in frequency and summated during chemical stimulation. SDPs originated from either the site of recording or from neighboring areas. When the SDPs attained a certain amplitude, they seemed to give rise to action potentials. Also, relatively well developed or partially blocked spikes (apparently originating elsewhere) were recorded from single nerve terminals. 6. The receptor (generator) potential of chemosensory receptors appears to be an integrated response formed by multiple activity originating in different nerve endings.

Action Potentials From Single Auditory-Nerve Fibers?

Science ◽  
1948 ◽  
Vol 108 (2810) ◽  
pp. 513-513 ◽  
Author(s):  
R. GALAMBOS ◽  
H. DAVIS
Keyword(s):  
Auditory Nerve ◽  
Action Potentials ◽  
Nerve Fibers ◽  
Auditory Nerve Fibers

Taste Responsiveness of Fungiform Taste Cells With Action Potentials

2006 ◽  
Vol 96 (6) ◽  
pp. 3088-3095 ◽  
Author(s):  
Ryusuke Yoshida ◽  
Noriatsu Shigemura ◽  
Keisuke Sanematsu ◽  
Keiko Yasumatsu ◽  
Satoru Ishizuka ◽  
...  
Keyword(s):  
Action Potentials ◽  
Basolateral Membrane ◽  
Extracellular Recording ◽  
Hierarchical Cluster ◽  
Nerve Fibers ◽  
Chorda Tympani ◽  
Cell Responses ◽  
Single Receptor ◽  
Gustatory Nerve ◽  
Taste Cells

It is known that a subset of taste cells generate action potentials in response to taste stimuli. However, responsiveness of these cells to particular tastants remains unknown. In the present study, by using a newly developed extracellular recording technique, we recorded action potentials from the basolateral membrane of single receptor cells in response to taste stimuli applied apically to taste buds isolated from mouse fungiform papillae. By this method, we examined taste-cell responses to stimuli representing the four basic taste qualities (NaCl, Na saccharin, HCl, and quinine-HCl). Of 72 cells responding to taste stimuli, 48 (67%) responded to one, 22 (30%) to two, and 2 (3%) to three of four taste stimuli. The entropy value presenting the breadth of responsiveness was 0.158 ± 0.234 (mean ± SD), which was close to that for the nerve fibers (0.183 ± 0.262). In addition, the proportion of taste cells predominantly sensitive to each of the four taste stimuli, and the grouping of taste cells based on hierarchical cluster analysis, were comparable with those of chorda tympani (CT) fibers. The occurrence of each class of taste cells with different taste responsiveness to the four taste stimuli was not significantly different from that of CT fibers except for classes with broad taste responsiveness. These results suggest that information derived from taste cells generating action potentials may provide the major component of taste information that is transmitted to gustatory nerve fibers.

Electrical properties and synaptic connections to neurons in parasympathetic colonic ganglia of the cat

1984 ◽  
Vol 247 (1) ◽  
pp. G52-G61
Author(s):  
J. Krier ◽  
D. A. Hartman
Keyword(s):  
Synaptic Input ◽  
Action Potentials ◽  
Distal Colon ◽  
Nerve Fibers ◽  
Synaptic Connections ◽  
Electrophysiological Properties ◽  
Intracellular Injection ◽  
Spontaneous Action ◽  
Spontaneous Action Potentials

Intracellular recording techniques were used in vitro to analyze the electrophysiological properties and synaptic connections to cat parasympathetic neurons in ganglia located on the serosal surface of the distal colon. Neurons were classified into two types. The first type exhibited spontaneous action potentials at regular and irregular interspike intervals. Spontaneous action potentials were 1) not abolished by superfusion of the ganglia with a modified Krebs solution containing low Ca2+, high Mg2+, or nicotinic ganglionic blocking agents, 2) reduced or abolished by intracellular injection of hyperpolarizing current, and 3) increased by intracellular injection of depolarizing current. We suggest that the generation of spontaneous action potentials may be due to an endogenous depolarizing mechanism and not to cholinergic synaptic input from other neurons located in the ganglia. The second type of neuron termed "quiescent" exhibited a stable transmembrane potential and elicited action potentials in response to electrical stimulation of nerve trunks. Both quiescent and spontaneously discharging neurons receive synaptic input from preganglionic fibers in the pelvic nerve and project their postganglionic axons to colonic nerve fibers that innervate effector structures in the colon.

Factors determining the frequency content of the electromyogram

1983 ◽  
Vol 55 (2) ◽  
pp. 392-399 ◽  
Author(s):  
H. Kranz ◽  
A. M. Williams ◽  
J. Cassell ◽  
D. J. Caddy ◽  
R. B. Silberstein
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Nerve Fibers ◽  
Frequency Content ◽  
Muscle Properties ◽  
Spectral Content ◽  
Unit Discharge ◽  
Compound Action Potentials ◽  
Motor Unit Discharge ◽  
Compound Action

The contribution of central and peripheral factors to the frequency content of the electromyogram was examined in 10 subjects performing maximal 45-s contractions of thenar muscles. The median frequencies (Fm) of surface-recorded electromyograms and compound action potentials were similar early (P greater than 0.6) and late (P greater than 0.5) in the contractions. There was a mean decrease in the Fm during contraction of 39% for electromyograms and 35% for compound potentials (P greater than 0.1). The Fm of electromyograms increased 11% (P less than 0.02) in only the 1st s of contraction as force was raised from 25 to 100% of maximum. Only one of five subjects showed evidence of increasing synchronization of motor unit discharge during contraction. There was no evidence that delay or dispersion of action potential propagation in terminal nerve fibers or at the neuromuscular junction had a significant effect on frequency content. The findings indicated that the spectral content of muscle electrical activity, and its shift during contraction, primarily reflects intrinsic muscle properties.

scholarly journals Intrinsic and synaptic properties of vertical cells of the mouse dorsal cochlear nucleus

2012 ◽  
Vol 108 (4) ◽  
pp. 1186-1198 ◽  
Author(s):  
Sidney P. Kuo ◽  
Hsin-Wei Lu ◽  
Laurence O. Trussell
Keyword(s):  
Cochlear Nucleus ◽  
Action Potentials ◽  
Fluorescent Protein ◽  
Nerve Fibers ◽  
Dorsal Cochlear Nucleus ◽  
Mammalian Brain ◽  
Fusiform Cell ◽  
Whole Cell Patch Clamp ◽  
Green Fluorescent ◽  
Vertical Cell

Multiple classes of inhibitory interneurons shape the activity of principal neurons of the dorsal cochlear nucleus (DCN), a primary target of auditory nerve fibers in the mammalian brain stem. Feedforward inhibition mediated by glycinergic vertical cells (also termed tuberculoventral or corn cells) is thought to contribute importantly to the sound-evoked response properties of principal neurons, but the cellular and synaptic properties that determine how vertical cells function are unclear. We used transgenic mice in which glycinergic neurons express green fluorescent protein (GFP) to target vertical cells for whole cell patch-clamp recordings in acute slices of DCN. We found that vertical cells express diverse intrinsic spiking properties and could fire action potentials at high, sustained spiking rates. Using paired recordings, we directly examined synapses made by vertical cells onto fusiform cells, a primary DCN principal cell type. Vertical cell synapses produced unexpectedly small-amplitude unitary currents in fusiform cells, and additional experiments indicated that multiple vertical cells must be simultaneously active to inhibit fusiform cell spike output. Paired recordings also revealed that a major source of inhibition to vertical cells comes from other vertical cells.

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