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Spontaneous action potentials and neural coding in unmyelinated axons
Cian O'Donnell1, Mark C W van Rossum
1Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh EH8 9AB, U.K., and Computational Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, U.S.A. cian@salk.edu.
Neural Computation
|January 21, 2015
Summary
Spontaneous neuron firing, caused by ion channel activity, can disrupt neural communication. This study reveals axon length affects firing rates and that these spontaneous spikes hinder signal transmission.
Area of Science:
- Neuroscience
- Computational Biology
- Biophysics
Background:
- Voltage-gated sodium (Na) and potassium (K) channels are crucial for neuronal action potential generation.
- Stochastic gating of ion channels can lead to spontaneous action potentials, even without external stimuli.
- Previous studies on spontaneous action potentials primarily used single-compartment models, limiting understanding of spatially extended neuronal structures.
Purpose of the Study:
- To investigate spontaneous action potential generation in spatially extended unmyelinated axons.
- To analyze the relationship between axon length and spontaneous firing rate.
- To determine the statistical properties of spontaneous activity and its impact on neural coding.
Main Methods:
- Computational simulations of unmyelinated axons incorporating stochastic ion channel gating.
- Analysis of spontaneous action potential rates as a function of axon length.
- Statistical analysis of spontaneous spike trains, including deviation from Poisson statistics.
- Modeling the effect of spontaneous spikes on the probability of first-spike transmission in neural coding.
Main Results:
- The spontaneous firing rate in unmyelinated axons exhibits a non-monotonic dependence on axon length.
- Spontaneous neural activity demonstrates sub-Poisson statistics, indicating regularity beyond random chance.
- Spontaneous spikes significantly reduce the probability of successfully transmitting the first spike in a neural signal train.
- This reduction in transmission probability can impair neural coding efficiency.
Conclusions:
- Axon length is a critical factor influencing spontaneous action potential generation in unmyelinated axons.
- The non-Poisson nature of spontaneous activity has implications for understanding neural signal reliability.
- Spontaneous firing poses a significant challenge to effective neural coding by interfering with signal transmission.
- Further research is needed to explore mechanisms for mitigating the impact of spontaneous activity on neural function.
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