Table of Contents
ISRN Computational Biology
Volume 2013, Article ID 230571, 11 pages
Research Article

All Phase Resetting Curves Are Bimodal, but Some Are More Bimodal Than Others

Department of Physics and Astronomy, College of Charleston, 66 George Street, Charleston, SC 29424, USA

Received 22 August 2013; Accepted 19 November 2013

Academic Editors: P. Durrens and A. Fedorov

Copyright © 2013 Sorinel A. Oprisan. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Phase resetting curves (PRCs) are phenomenological and quantitative tools that tabulate the transient changes in the firing period of endogenous neural oscillators as a result of external stimuli, for example, presynaptic inputs. A brief current perturbation can produce either a delay (positive phase resetting) or an advance (negative phase resetting) of the subsequent spike, depending on the timing of the stimulus. We showed that any planar neural oscillator has two remarkable points, which we called neutral points, where brief current perturbations produce no phase resetting and where the PRC flips its sign. Since there are only two neutral points, all PRCs of planar neural oscillators are bimodal. The degree of bimodality of a PRC, that is, the ratio between the amplitudes of the delay and advance lobes of a PRC, can be smoothly adjusted when the bifurcation scenario leading to stable oscillatory behavior combines a saddle node of invariant circle (SNIC) and an Andronov-Hopf bifurcation (HB).