Presynaptic Na/Ca action potentials in unmyelinated axons of olfactory cortex

1988 ◽  
Vol 411 (2) ◽  
pp. 180-187 ◽  
Author(s):  
C. N. Scholfield
Keyword(s):  
Action Potentials ◽  
Olfactory Cortex ◽  
Unmyelinated Axons

scholarly journals Axonal blockage with microscopic magnetic stimulation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jordan Skach ◽  
Catherine Conway ◽  
Lauryn Barrett ◽  
Hui Ye
Keyword(s):  
High Frequency ◽  
Action Potentials ◽  
Compartment Model ◽  
Clinical Settings ◽  
Magnetic Coil ◽  
Unmyelinated Axons ◽  
Activation Dynamics ◽  
Underlying Mechanisms ◽  
Bio Compatibility ◽  
Interesting Alternative

Abstract Numerous neurological dysfunctions are characterized by undesirable nerve activity. By providing reversible nerve blockage, electric stimulation with an implanted electrode holds promise in the treatment of these conditions. However, there are several limitations to its application, including poor bio-compatibility and decreased efficacy during chronic implantation. A magnetic coil of miniature size can mitigate some of these problems, by coating it with biocompatible material for chronic implantation. However, it is unknown if miniature coils could be effective in axonal blockage and, if so, what the underlying mechanisms are. Here we demonstrate that a submillimeter magnetic coil can reversibly block action potentials in the unmyelinated axons from the marine mollusk Aplysia californica. Using a multi-compartment model of the Aplysia axon, we demonstrate that the miniature coil causes a significant local depolarization in the axon, alters activation dynamics of the sodium channels, and prevents the traveling of the invading action potentials. With improved biocompatibility and capability of emitting high-frequency stimuli, micro coils provide an interesting alternative for electric blockage of axonal conductance in clinical settings.

scholarly journals Spontaneous Action Potentials and Neural Coding in Unmyelinated Axons

2015 ◽  
Vol 27 (4) ◽  
pp. 801-818 ◽  
Author(s):  
Cian O’Donnell ◽  
Mark C. W. van Rossum
Keyword(s):  
Action Potentials ◽  
Neural Coding ◽  
Unmyelinated Axon ◽  
Action Potential Generation ◽  
Potential Generation ◽  
Unmyelinated Axons ◽  
Single Compartment ◽  
Spatially Extended ◽  
Spontaneous Action ◽  
Spontaneous Action Potentials

The voltage-gated Na and K channels in neurons are responsible for action potential generation. Because ion channels open and close in a stochastic fashion, spontaneous (ectopic) action potentials can result even in the absence of stimulation. While spontaneous action potentials have been studied in detail in single-compartment models, studies on spatially extended processes have been limited. The simulations and analysis presented here show that spontaneous rate in unmyelinated axon depends nonmonotonically on the length of the axon, that the spontaneous activity has sub-Poisson statistics, and that neural coding can be hampered by the spontaneous spikes by reducing the probability of transmitting the first spike in a train.

scholarly journals Short-Latency Single Unit Processing in Olfactory Cortex

1991 ◽  
Vol 3 (3) ◽  
pp. 293-299 ◽  
Author(s):  
Jonn McCollum ◽  
John Larson ◽  
Tim Otto ◽  
Frank Schottler ◽  
Richard Granger ◽  
...  
Keyword(s):  
Action Potentials ◽  
Single Unit ◽  
Piriform Cortex ◽  
Olfactory Cortex ◽  
Cell Type ◽  
Unit Recording ◽  
Class A ◽  
Monophasic Action Potentials ◽  
Total Cell Population ◽  
Unit Processing

Single-unit recording of layer II—III cells in olfactory (piriform) cortex was performed on awake, unrestrained rats actively engaged in learning novel odors in an olfactory discrimination task. Five of the 67 cells tested had very brief monophasic action potentials and high spontaneous firing rates (30–80 Hz); it is suggested that these units were interneurons. The remainder of the neurons had broader spikes and did not discharge for prolonged periods. Thirty-nine percent of the broad spike cells responded to at least one and usually more of the odors presented to the rats during either of the first two trials on which that odor was present, but, in most cases, these responses occurred only very infrequently over the course of subsequent trials. Six percent of the broad-spike group, how ever, continued firing robustly to a single odor but not to others. From these results it appears that most cells in piriform cortex do not respond to most odors, i.e., coding is exceedingly sparse. A subgroup of the predominant broad-spike cell type does react to several odors but this response drops out with repeated exposure, perhaps because of training. However, a few members of this class (a small fraction of the total cell population) do go on responding to a particular odor, thus exhibiting a form of odor specificity. The results are discussed with regard to predictions from recently developed models of the olfactory cortex.

scholarly journals Precise spatiotemporal control of voltage-gated sodium channels by photocaged saxitoxin

2020 ◽  
Author(s):  
Anna V. Elleman ◽  
Gabrielle Devienne ◽  
Christopher D. Makinson ◽  
Allison L. Haynes ◽  
John R. Huguenard ◽  
...  
Keyword(s):  
Action Potentials ◽  
Neuronal Excitability ◽  
Differential Susceptibility ◽  
Fiber Bundles ◽  
Protecting Group ◽  
Voltage Gated ◽  
Unmyelinated Axons ◽  
Voltage Gated Sodium Channels ◽  
Sodium Ion Channels ◽  
Spatiotemporal Control

SummaryHere we report the pharmacologic blockade of voltage-gated sodium ion channels (NaV) by a synthetic saxitoxin derivative affixed to a photocleavable protecting group. We demonstrate that a functionalized saxitoxin (STX-eac) enables exquisite spatiotemporal control of NaV blockade to interrupt action potentials (APs) in dissociated neurons and nerve fiber bundles. The photo-uncaged inhibitor (STX-ea) is a nanomolar potent, reversible binder of NaVs. We use STX-eac to reveal differential susceptibility of myelinated and unmyelinated axons in the corpus callosum to NaV-dependent alterations in AP propagation, with unmyelinated axons preferentially showing reduced AP fidelity under conditions of partial NaV blockade. These results validate STX-eac as a high precision tool for robust photocontrol of neuronal excitability and AP generation.

scholarly journals Precise spatiotemporal control of voltage-gated sodium channels by photocaged saxitoxin

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anna V. Elleman ◽  
Gabrielle Devienne ◽  
Christopher D. Makinson ◽  
Allison L. Haynes ◽  
John R. Huguenard ◽  
...  
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Neuronal Excitability ◽  
Differential Susceptibility ◽  
Protecting Group ◽  
Voltage Gated ◽  
Unmyelinated Axons ◽  
Voltage Gated Sodium Channels ◽  
Sodium Ion Channels ◽  
Spatiotemporal Control

AbstractHere we report the pharmacologic blockade of voltage-gated sodium ion channels (NaVs) by a synthetic saxitoxin derivative affixed to a photocleavable protecting group. We demonstrate that a functionalized saxitoxin (STX-eac) enables exquisite spatiotemporal control of NaVs to interrupt action potentials in dissociated neurons and nerve fiber bundles. The photo-uncaged inhibitor (STX-ea) is a nanomolar potent, reversible binder of NaVs. We use STX-eac to reveal differential susceptibility of myelinated and unmyelinated axons in the corpus callosum to NaV-dependent alterations in action potential propagation, with unmyelinated axons preferentially showing reduced action potential fidelity under conditions of partial NaV block. These results validate STX-eac as a high precision tool for robust photocontrol of neuronal excitability and action potential generation.

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