The basis of sharp spike onset in standard biophysical models (Telenczuk et al 2017)

"In most vertebrate neurons, spikes initiate in the axonal initial segment (AIS). When recorded in the soma, they have a surprisingly sharp onset, as if sodium (Na) channels opened abruptly. The main view stipulates that spikes initiate in a conventional manner at the distal end of the AIS, then progressively sharpen as they backpropagate to the soma. We examined the biophysical models used to substantiate this view, and we found that spikes do not initiate through a local axonal current loop that propagates along the axon, but through a global current loop encompassing the AIS and soma, which forms an electrical dipole. Therefore, the phenomenon is not adequately modeled as the backpropagation of an electrical wave along the axon, since the wavelength would be as large as the entire system. Instead, in these models, we found that spike initiation rather follows the critical resistive coupling model proposed recently, where the Na current entering the AIS is matched by the axial resistive current flowing to the soma. ..."

Model Type: Axon; Neuron or other electrically excitable cell

Currents: I Sodium

Model Concept(s): Axonal Action Potentials; Action Potential Initiation

Simulation Environment: NEURON (web link to model); Python (web link to model)

Implementer(s): Telenczuk, Maria [mtelenczuk at]; Fontaine, Bertrand


Telenczuk M, Fontaine B, Brette R. (2017). The basis of sharp spike onset in standard biophysical models. PloS one. 12 [PubMed]

This website requires cookies and limited processing of your personal data in order to function. By continuing to browse or otherwise use this site, you are agreeing to this use. See our Privacy policy and how to cite and terms of use.