Temperature-sensitive conduction failure at axon branch points

1978 ◽  
Vol 41 (1) ◽  
pp. 1-8 ◽  
Author(s):  
M. Westerfield ◽  
R. W. Joyner ◽  
J. W. Moore
Keyword(s):  
Action Potential ◽  
High Temperatures ◽  
Computer Simulations ◽  
Action Potentials ◽  
Critical Ratio ◽  
Temperature Sensitive ◽  
Branch Points ◽  
Action Potential Propagation ◽  
Conduction Failure ◽  
Axon Branch

1. The propagation of action potentials through the branching regions of squid axons was examined experimentally and with computer simulations over a temperature range of 5-25 degrees C. 2. Above a critical ratio of postbranch to prebranch diameters, propagation of an action potential failed. The value of this critical ratio is very sensitive to temperature and is smaller at high temperatures. The experimentally measured Q10 of the critical ratio is 0.37 +/- 0.04. 3. Evaluation of a number of parameters of action-potential propagation showed that this effect is closely related to the change in the width of the action potential with temperature (Q10 = 0.29 +/- 0.01).

scholarly journals Action Potential Reflection and Failure at Axon Branch Points Cause Stepwise Changes in EPSPs in a Neuron Essential for Learning

2000 ◽  
Vol 83 (3) ◽  
pp. 1693-1700 ◽  
Author(s):  
Stephen A. Baccus ◽  
Brian D. Burrell ◽  
Christie L. Sahley ◽  
Kenneth J. Muller
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Conduction Block ◽  
Neuronal Morphology ◽  
Whole Body ◽  
Reverse Direction ◽  
Mammalian Brain ◽  
Branch Points ◽  
Individual Branch ◽  
Axon Branch

In leech mechanosensory neurons, action potentials reverse direction, or reflect, at central branch points. This process enhances synaptic transmission from individual axon branches by rapidly activating synapses twice, thereby producing facilitation. At the same branch points action potentials may fail to propagate, which can reduce transmission. It is now shown that presynaptic action potential reflection and failure under physiological conditions influence transmission to the same postsynaptic neuron, the S cell. The S cell is an interneuron essential for a form of nonassociative learning, sensitization of the whole body shortening reflex. The P to S synapse has components that appear monosynaptic (termed “direct”) and polysynaptic, both with glutamatergic pharmacology. Reflection at P cell branch points on average doubled transmission to the S cell, whereas action potential failure, or conduction block, at the same branch points decreased it by one-half. Each of two different branch points affected transmission, indicating that the P to S connection is spatially distributed around these branch points. This was confirmed by examining the locations of individual contacts made by the P cell with the S cell and its electrically coupled partner C cells. These results show that presynaptic neuronal morphology produces a range of transmission states at a set of synapses onto a neuron necessary for a form of learning. Reflection and conduction block are activity-dependent and are basic properties of action potential propagation that have been seen in other systems, including axons and dendrites in the mammalian brain. Individual branch points and the distribution of synapses around those branch points can substantially influence neuronal transmission and plasticity.

scholarly journals An automated method for precise axon reconstruction from recordings of high-density micro-electrode arrays

2021 ◽  
Author(s):  
Alessio Paolo Buccino ◽  
Xinyue Yuan ◽  
Vishalini Emmenegger ◽  
Xiaohan Xue ◽  
Tobias Gaenswein ◽  
...  
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Electrical Potential ◽  
Simulated Data ◽  
Signal Propagation ◽  
High Density ◽  
Electrode Arrays ◽  
Action Potential Propagation ◽  
Automated Method ◽  
Propagation Velocities

Neurons communicate with each other by sending action potentials through their axons. The velocity of axonal signal propagation describes how fast electrical action potentials can travel, and can be affected in a human brain by several pathologies, including multiple sclerosis, traumatic brain injury and channelopathies. High-density microelectrode arrays (HD-MEAs) provide unprecedented spatio-temporal resolution to extracellularly record neural electrical activity. The high density of the recording electrodes enables to image the activity of individual neurons down to subcellular resolution, which includes the propagation of axonal signals. However, axon reconstruction, to date, mainly relies on a manual approach to select the electrodes and channels that seemingly record the signals along a specific axon, while an automated approach to track multiple axonal branches in extracellular action-potential recordings is still missing. In this article, we propose a fully automated approach to reconstruct axons from extracellular electrical-potential landscapes, so-called "electrical footprints" of neurons. After an initial electrode and channel selection, the proposed method first constructs a graph, based on the voltage signal amplitudes and latencies. Then, the graph is interrogated to extract possible axonal branches. Finally, the axonal branches are pruned and axonal action-potential propagation velocities are computed. We first validate our method using simulated data from detailed reconstructions of neurons, showing that our approach is capable of accurately reconstructing axonal branches. We then apply the reconstruction algorithm to experimental recordings of HD-MEAs and show that it can be used to determine axonal morphologies and signal-propagation velocities at high throughput. We introduce a fully automated method to reconstruct axonal branches and estimate axonal action-potential propagation velocities using HD-MEA recordings. Our method yields highly reliable and reproducible velocity estimations, which constitute an important electrophysiological feature of neuronal preparations.

Multiple Sites of Spike Initiation in a Bifurcating Locust Neurone

1978 ◽  
Vol 76 (1) ◽  
pp. 63-84 ◽  
Author(s):  
W. J. HEITLER ◽  
COREY S. GOODMAN
Keyword(s):  
Action Potential ◽  
Branch Point ◽  
Peripheral Nerves ◽  
Action Potentials ◽  
Room Temperature ◽  
Initiation Site ◽  
Left And Right ◽  
Axon Branch ◽  
Spike Initiation ◽  
Dorsal Unpaired Median

Recordings were made from the metathoracic dorsal unpaired median neurone to the extensor tibiae muscle (DUMETi) in the locust. This is a bifurcating neurone with axons exiting both sideS of the ganglion, whose soma can support a full action potential. Four different spike types were recorded in the soma, each of which we associate with a different region of the neurone. These were (1) a soma (S) spike of 70-90 mV, (2) a neurite (N) spike of 20-40 mV, occurring between the axon hillock and axon branch point, (3) and (4) axon (A) spikes of 8–15 mV, occurring distal to the branch point on the left and right axons. Each of these regions must therefore have its own spike initiation site. At spike frequencies greater than about 10 Hz at room temperature or 1-5 Hz at 32 °C (the preferred environmental temperature of the locust) the S-spike may fail, revealing A-spikes, or more rarely N-spikes. A-spikes usually consist of two more-or-less separate components, Al and Ar, which can be correlated with action potentials in the left and right axon branches by recording spikes extracellularly in the peripheral nerves on each side. Occasionally single component A-spikes occur when an action potential is initiated in only one axon, and fails to propagate across the branch point to the contralateral axon. Thus, action potentials may occur independently in the branches of this bifurcating neurone. After unilateral axotomy only S-spikes and N-spikes are recorded, indicating that action potentials no longer fail to propagate across the branch point. Anatomical asymmetries in the axon branches of DUMETi have been correlated with physiological asymmetries recorded in the soma of the same neurone.

Computer Simulation of the Neuronal Action Potential

1988 ◽  
Vol 15 (1) ◽  
pp. 46-47 ◽  
Author(s):  
Paul R. Solomon ◽  
Scott Cooper ◽  
Dean Pomerleau
Keyword(s):  
Computer Simulation ◽  
Action Potential ◽  
Sodium Channel ◽  
Computer Simulations ◽  
Action Potentials ◽  
Channel Blocker ◽  
Neuronal Membrane ◽  
Excitatory Postsynaptic Potential ◽  
Sodium Channel Blocker ◽  
Postsynaptic Potential

A series of computer simulations of the neuronal resting and action potentials are described. These programs are designed to allow the user to observe the movement of ions across a neuronal membrane during: (a) an action potential, (b) a subthreshold excitatory postsynaptic potential (EPSP), (c) an inhibitory postsynaptic potential, and (d) a suprathreshold EPSP in the presence of the sodium channel blocker tetrodotoxin (TTX).

scholarly journals Action Potential Propagation and Synchronisation in Myelinated Axons

2019 ◽  
Author(s):  
Helmut Schmidt ◽  
Thomas R. Knösche
Keyword(s):  
White Matter ◽  
Action Potential ◽  
Myelin Sheath ◽  
Action Potentials ◽  
Structural Parameters ◽  
Node Of Ranvier ◽  
Model Parameters ◽  
Mathematical Framework ◽  
Whole Brain ◽  
Action Potential Propagation

AbstractWith the advent of advanced MRI techniques it has become possible to study axonal white matter non-invasively and in great detail. Measuring the various parameters of the long-range connections of the brain opens up the possibility to build and refine detailed models of large-scale neuronal activity. One particular challenge is to find a mathematical description of action potential propagation that is sufficiently simple, yet still biologically plausible to model signal transmission across entire axonal fibre bundles. We develop a mathematical framework in which we replace the Hodgkin-Huxley dynamics by a spike-diffuse-spike model with passive sub-threshold dynamics and explicit, threshold-activated ion channel currents. This allows us to study in detail the influence of the various model parameters on the action potential velocity and on the entrainment of action potentials between ephaptically coupled fibres without having to recur to numerical simulations. Specifically, we recover known results regarding the influence of axon diameter, node of Ranvier length and internode length on the velocity of action potentials. Additionally, we find that the velocity depends more strongly on the thickness of the myelin sheath than was suggested by previous theoretical studies. We further explain the slowing down and synchronisation of action potentials in ephaptically coupled fibres by their dynamic interaction. In summary, this study presents a solution to incorporate detailed axonal parameters into a whole-brain modelling framework.Author summaryWith more and more data becoming available on white-matter tracts, the need arises to develop modelling frameworks that incorporate these data at the whole-brain level. This requires the development of efficient mathematical schemes to study parameter dependencies that can then be matched with data, in particular the speed of action potentials that cause delays between brain regions. Here, we develop a method that describes the formation of action potentials by threshold activated currents, often referred to as spike-diffuse-spike modelling. A particular focus of our study is the dependence of the speed of action potentials on structural parameters. We find that the diameter of axons and the thickness of the myelin sheath have a strong influence on the speed, whereas the length of myelinated segments and node of Ranvier length have a lesser effect. In addition to examining single axons, we demonstrate that action potentials between nearby axons can synchronise and slow down their propagation speed.

scholarly journals Recording action potential propagation in single axons using multi-electrode arrays

2017 ◽  
Author(s):  
Kenneth R. Tovar ◽  
Daniel C. Bridges ◽  
Bian Wu ◽  
Connor Randall ◽  
Morgane Audouard ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Action Potential ◽  
Sodium Channels ◽  
Action Potentials ◽  
Extracellular Recording ◽  
Electrode Arrays ◽  
Action Potential Propagation ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Axonal Arbors

AbstractThe small caliber of central nervous system (CNS) axons makes routine study of axonal physiology relatively difficult. However, while recording extracellular action potentials from neurons cultured on planer multi-electrode arrays (MEAs) we found activity among groups of electrodes consistent with action potential propagation in single neurons. Action potential propagation was evident as widespread, repetitive cooccurrence of extracellular action potentials (eAPs) among groups of electrodes. These eAPs occurred with invariant sequences and inter-electrode latencies that were consistent with reported measures of action potential propagation in unmyelinated axons. Within co-active electrode groups, the inter-electrode eAP latencies were temperature sensitive, as expected for action potential propagation. Our data are consistent with these signals primarily reflecting axonal action potential propagation, from axons with a high density of voltage-gated sodium channels. Repeated codetection of eAPs by multiple electrodes confirmed these eAPs are from individual neurons and averaging these eAPs revealed sub-threshold events at other electrodes. The sequence of electrodes at which eAPs co-occur uniquely identifies these neurons, allowing us to monitor spiking of single identified neurons within neuronal ensembles. We recorded dynamic changes in single axon physiology such as simultaneous increases and decreases in excitability in different portions of single axonal arbors over several hours. Over several weeks, we measured changes in inter-electrode propagation latencies and ongoing changes in excitability in different regions of single axonal arbors. We recorded action potential propagation signals in human induced pluripotent stem cell-derived neurons which could thus be used to study axonal physiology in human disease models.Significance StatementStudying the physiology of central nervous system axons is limited by the technical challenges of recording from axons with pairs of patch or extracellular electrodes at two places along single axons. We studied action potential propagation in single axonal arbors with extracellular recording with multi-electrode arrays. These recordings were non-invasive and were done from several sites of small caliber axons and branches. Unlike conventional extracellular recording, we unambiguously identified and labelled the neuronal source of propagating action potentials. We manipulated and quantified action potential propagation and found a surprisingly high density of axonal voltage-gated sodium channels. Our experiments also demonstrate that the excitability of different portions of axonal arbors can be independently regulated on time scales from hours to weeks.

Images of Action Potential Propagation in Heart

Physiology ◽  
2000 ◽  
Vol 15 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Guy Salama ◽  
Bum-Rak Choi
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Fiber Structure ◽  
Intercellular Coupling ◽  
Av Node ◽  
Action Potential Propagation ◽  
Voltage Sensitive Dyes

Activation and repolarization across mammalian hearts follow complex three-dimensional pathways that are governed by fiber structure, intercellular coupling, and action potentials (APs) with spatially heterogeneous properties. Voltage-sensitive dyes and imaging techniques offer new insights on how spatiotemporal heterogeneities of APs govern propagation, repolarization, and AV node conduction and help us visualize arrhythmias with previously unattainable details.

scholarly journals Action potential propagation recorded from single axonal arbors using multielectrode arrays

2018 ◽  
Vol 120 (1) ◽  
pp. 306-320 ◽  
Author(s):  
Kenneth R. Tovar ◽  
Daniel C. Bridges ◽  
Bian Wu ◽  
Connor Randall ◽  
Morgane Audouard ◽  
...  
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Hippocampal Neurons ◽  
Detection Threshold ◽  
Physiological Data ◽  
Low Density ◽  
Multielectrode Arrays ◽  
Action Potential Propagation ◽  
Voltage Gated ◽  
Axonal Arbors

We report the presence of co-occurring extracellular action potentials (eAPs) from cultured mouse hippocampal neurons among groups of planar electrodes on multielectrode arrays (MEAs). The invariant sequences of eAPs among coactive electrode groups, repeated co-occurrences, and short interelectrode latencies are consistent with action potential propagation in unmyelinated axons. Repeated eAP codetection by multiple electrodes was widespread in all our data records. Codetection of eAPs confirms they result from the same neuron and allows these eAPs to be isolated from all other spikes independently of spike sorting algorithms. We averaged co-occurring events and revealed additional electrodes with eAPs that would otherwise be below detection threshold. We used these eAP cohorts to explore the temperature sensitivity of action potential propagation and the relationship between voltage-gated sodium channel density and propagation velocity. The sequence of eAPs among coactive electrodes “fingerprints” neurons giving rise to these events and identifies them within neuronal ensembles. We used this property and the noninvasive nature of extracellular recording to monitor changes in excitability at multiple points in single axonal arbors simultaneously over several hours, demonstrating independence of axonal segments. Over several weeks, we recorded changes in interelectrode propagation latencies and ongoing changes in excitability in different regions of single axonal arbors. Our work illustrates how repeated eAP co-occurrences can be used to extract physiological data from single axons with low-density MEAs. However, repeated eAP co-occurrences lead to oversampling spikes from single neurons and thus can confound traditional spike-train analysis. NEW & NOTEWORTHY We studied action potential propagation in single axons using low-density multielectrode arrays. We unambiguously identified the neuronal sources of propagating action potentials and recorded extracellular action potentials from several positions within single axonal arbors. We found a surprisingly high density of axonal voltage-gated sodium channels responsible for a high propagation safety factor. Our experiments also demonstrate that excitability in different segments of single axons is regulated independently on timescales from hours to weeks.

scholarly journals An Algorithm for Tracking the Position and Velocity of Multiple Neuronal Signals Using Implantable Microelectrodes In Vivo

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1346
Author(s):  
Lionel M. Broche ◽  
Karla D. Bustamante ◽  
Michael Pycraft Hughes
Keyword(s):  
Nervous System ◽  
Action Potential ◽  
Small Groups ◽  
Action Potentials ◽  
Interconnected Network ◽  
Electrode Arrays ◽  
Action Potential Propagation ◽  
Physical Form

Increasingly complex multi-electrode arrays for the study of neurons both in vitro and in vivo have been developed with the aim of tracking the conduction of neural action potentials across a complex interconnected network. This is usually performed through the use of electrodes to record from single or small groups of microelectrodes, and using only one electrode to monitor an action potential at any given time. More complex high-density electrode structures (with thousands of electrodes or more) capable of tracking action potential propagation have been developed but are not widely available. We have developed an algorithm taking data from clusters of electrodes positioned such that action potentials are detected by multiple sites, and using this to detect the location and velocity of action potentials from multiple neurons. The system has been tested by analyzing recordings from probes implanted into the locust nervous system, where recorded positions and velocities correlate well with the known physical form of the nerve.

Sign in / Sign up

Export Citation Format

Share Document