Electrical interactions via the extracellular potential near cell bodies
1Computation and Neural Systems Program, California Institute of Technology, Pasadena 91125, USA. holt@lnc.usc.edu
Journal of Computational Neuroscience
|May 20, 1999
Summary
Ephaptic interactions near neuron cell bodies are stronger than in fiber tracts. This study models these interactions, finding induced voltages that could influence neural signaling.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Electrophysiology
Background:
- Ephaptic interactions, or electrical field effects, occur between neurons.
- These interactions are hypothesized to be stronger near neuron cell bodies compared to within axonal fiber tracts due to differences in signal amplitude and spatial confinement.
Purpose of the Study:
- To estimate the extracellular potentials generated by an action potential in a cortical pyramidal cell.
- To calculate the ephaptically induced polarization in a nearby passive cable due to these extracellular potentials.
- To explore the functional relevance of these induced voltages in neural communication.
Main Methods:
- Utilized standard one-dimensional cable theory to model neuronal electrical activity.
- Applied volume conductor theory to estimate extracellular potentials.
- Computed induced polarization in a passive cable based on simulated extracellular potentials.
Main Results:
- Extracellular action potentials near cell bodies are larger and more spatially confined than in fiber tracts.
- The model predicted ephaptically induced voltages of several millivolts in nearby passive cables.
- This induced voltage showed weak dependence on the cable's passive properties and did not spread electrotonically.
Conclusions:
- Ephaptic interactions near the cell body are significant due to larger, localized extracellular potentials.
- Induced voltages can influence nearby neuronal elements without significant electrotonic spread.
- These findings suggest a potential role for ephaptic coupling in modulating neural signaling and spike initiation.
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