Authors: A V Chizhov E Yu Smirnova K Kh Kim A V Zaitsev
Publish Date: 2014/01/29
Volume: 37, Issue: 1, Pages: 181-191
Abstract
Characteristics of action potential generation are important to understanding brain functioning and thus must be understood and modeled It is still an open question what model can describe concurrently the phenomena of sharp spike shape the spike threshold variability and the divisive effect of shunting on the gain of frequencycurrent dependence We reproduced these three effects experimentally by patchclamp recordings in cortical slices but we failed to simulate them by any of 11 known neuron models including one and multicompartment with HodgkinHuxley and Markov equationbased sodium channel approximations and those taking into account sodium channel subtype heterogeneity Basing on our voltageclamp data characterizing the dependence of sodium channel activation threshold on history of depolarization we propose a 3state Markov model with a closedtoopen state transition threshold dependent on slow inactivation This model reproduces the all three phenomena As a reduction of this model a leaky integrateandfire model with a dynamic threshold also shows the effect of gain reduction by shunt These results argue for the mechanism of gain reduction through threshold dynamics determined by the slow inactivation of sodium channels
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