scholarly journals Neuronal adaptation involves rapid expansion of the action potential initiation site

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Ricardo S. Scott ◽  
Christian Henneberger ◽  
Ragunathan Padmashri ◽  
Stefanie Anders ◽  
Thomas P. Jensen ◽  
...  
Keyword(s):  
Action Potential ◽  
Initiation Site ◽  
Rapid Expansion ◽  
Neuronal Adaptation ◽  
Action Potential Initiation ◽  
Potential Initiation

scholarly journals Electrophysiological Assessment of the Cutaneous Arborization of Aδ-Fiber Nociceptors

1999 ◽  
Vol 82 (3) ◽  
pp. 1164-1177 ◽  
Author(s):  
Yuan B. Peng ◽  
Matthias Ringkamp ◽  
James N. Campbell ◽  
Richard A. Meyer
Keyword(s):  
Receptive Field ◽  
Action Potential ◽  
Branch Point ◽  
Functional Anatomy ◽  
Initiation Site ◽  
Propagation Time ◽  
Branch Points ◽  
Action Potential Initiation ◽  
The Mean ◽  
Potential Initiation

Little is known about the relationship between the branching structure and function of physiologically identified cutaneous nociceptor terminals. The axonal arborization itself, however, has an impact on the afferent signal that is conveyed along the parent axon to the CNS. We therefore developed electrophysiological techniques to investigate the branching structure of cutaneous nociceptors. Single-fiber recordings were obtained from physiologically identified nociceptors that innervated the hairy skin of the monkey. Electrodes for transcutaneous stimulation were fixed at two separate locations inside the receptive field. For 32 Aδ-fiber nociceptors, distinct steps in latency of the recorded action potential were observed as the intensity of the transcutaneous electrical stimulus increased, indicating discrete sites for action potential initiation. The number of discrete latencies at each stimulation location ranged from 1 to 9 (3.7 ± 0.2; mean ± SE) and the mean size of the latency step was 9.9 ± 1.0 ms (range: 0.4–89.1 ms). For seven Aδ fibers, collision techniques were used to locate the position of the branch point where the daughter fibers that innervated the two locations within the receptive field join the parent axon. To correct for changes in electrical excitability at the peripheral terminals, collision experiments between the two skin locations and between each skin location and a nerve trunk electrode were necessary. Nine branch points were studied in the seven Aδ fibers; the mean propagation time from the action potential initiation site to the branch point was 31 ± 5 ms corresponding to a distance of 54 ± 10 mm. Almost half of the daughter branches were unmyelinated. These results demonstrate that collision techniques can be used to study the functional anatomy of physiologically identified nociceptive afferent terminals. Furthermore these results indicate that some nociceptive afferents branch quite proximal to their peripheral receptive field. Occlusion of action potential activity can occur in these long branches such that the shorter branches dominate in the response to natural stimuli.

Electrode configuration influences action potential initiation site and ensemble stochastic response properties

2003 ◽  
Vol 175 (1-2) ◽  
pp. 200-214 ◽  
Author(s):  
Charles A. Miller ◽  
Paul J Abbas ◽  
Kirill V Nourski ◽  
Ning Hu ◽  
Barbara K Robinson
Keyword(s):  
Action Potential ◽  
Initiation Site ◽  
Electrode Configuration ◽  
Stochastic Response ◽  
Response Properties ◽  
Action Potential Initiation ◽  
Potential Initiation

scholarly journals Differential Effects of Axon Initial Segment and Somatodendritic GABAA Receptors on Excitability Measures in Rat Dentate Granule Neurons

2011 ◽  
Vol 105 (1) ◽  
pp. 366-379 ◽  
Author(s):  
Patricio Rojas ◽  
Alejandro Akrouh ◽  
Lawrence N. Eisenman ◽  
Steven Mennerick
Keyword(s):  
Action Potential ◽  
Initial Segment ◽  
Input Resistance ◽  
Receptor Activation ◽  
Axon Initial Segment ◽  
Granule Neurons ◽  
Voltage Threshold ◽  
Granule Neuron ◽  
Action Potential Initiation ◽  
Potential Initiation

GABAA receptors are found on the somatodendritic compartment and on the axon initial segment of many principal neurons. The function of axonal receptors remains obscure, although it is widely assumed that axonal receptors must have a strong effect on excitability. We found that activation of GABAA receptors on the dentate granule neuron axon initial segment altered excitability by depolarizing the voltage threshold for action potential initiation under conditions that minimally affected overall cell input resistance. In contrast, activation of somatic GABAA receptors strongly depressed the input resistance of granule neurons without affecting the voltage threshold of action potential initiation. Although these effects were observed over a range of intracellular chloride concentrations, average voltage threshold was unaffected when ECl rendered GABAA axon initial segment responses explicitly excitatory. A compartment model of a granule neuron confirmed these experimental observations. Low ambient agonist concentrations designed to activate granule neuron tonic currents did not stimulate axonal receptors sufficiently to raise voltage threshold. Using excitatory postsynaptic current (EPSC)-like depolarizations, we show physiological consequences of axonal versus somatic GABAA receptor activation. With axonal inhibition, individual excitatory postsynaptic potentials (EPSPs) largely retained their amplitude and time course, but EPSPs that were suprathreshold under basal conditions failed to reach threshold with GABAA activation. By contrast, somatic inhibition depressed individual EPSPs because of strong shunting. Our results suggest that axonal GABAA receptors have a privileged effect on voltage threshold and that two major measures of neuronal excitability, voltage threshold and rheobase, are differentially affected by axonal and somatic GABAA receptor activation.

scholarly journals Somatic modulation of ectopic action potential initiation in distal axons

2018 ◽  
Vol 596 (21) ◽  
pp. 5067-5068
Author(s):  
Aurélie Fékété ◽  
Dominique Debanne
Keyword(s):  
Action Potential ◽  
Action Potential Initiation ◽  
Potential Initiation
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