Modelling the effects of ephaptic coupling on selectivity and response patterns during artificial stimulation of peripheral nerves

PLoS Comput Biol. 2020 Jun 1;16(6):e1007826. doi: 10.1371/journal.pcbi.1007826. eCollection 2020 Jun.


Artificial electrical stimulation of peripheral nerves for sensory feedback restoration can greatly benefit from computational models for simulation-based neural implant design in order to reduce the trial-and-error approach usually taken, thus potentially significantly reducing research and development costs and time. To this end, we built a computational model of a peripheral nerve trunk in which the interstitial space between the fibers and the tissues was modelled using a resistor network, thus enabling distance-dependent ephaptic coupling between myelinated axons and between fascicles as well. We used the model to simulate a) the stimulation of a nerve trunk model with a cuff electrode, and b) the propagation of action potentials along the axons. Results were used to investigate the effect of ephaptic interactions on recruitment and selectivity stemming from artificial (i.e., neural implant) stimulation and on the relative timing between action potentials during propagation. Ephaptic coupling was found to increase the number of fibers that are activated by artificial stimulation, thus reducing the artificial currents required for axonal recruitment, and it was found to reduce and shift the range of optimal stimulation amplitudes for maximum inter-fascicular selectivity. During propagation, while fibers of similar diameters tended to lock their action potentials and reduce their conduction velocities, as expected from previous knowledge on bundles of identical axons, the presence of many other fibers of different diameters was found to make their interactions weaker and unstable.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials*
  • Algorithms
  • Animals
  • Axons / metabolism
  • Axons / physiology
  • Computer Simulation
  • Electric Stimulation / methods*
  • Electrodes, Implanted
  • Humans
  • Models, Neurological*
  • Neural Conduction
  • Peripheral Nerves / physiology*
  • Peripheral Nervous System / physiology*
  • Ranvier's Nodes / physiology

Grant support

This study was funded by the Engineering and Physical Sciences Research Council (EPSRC; through the Grant EP/M025977/1, “Enabling Technologies for Sensory Feedback in Next-Generation Assistive Devices” ( The initials of the authors who received this award are KN, EKJC, DPS, FS, LJ, RJOC, and TGC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.