a small fraction of strongly cooperative sodium channels boosts neuronal encoding of high frequencies紧密合作的一小部分钠离子通道促进神经编码的高频率.pdfVIP

A Small Fraction of Strongly Cooperative Sodium Channels Boosts Neuronal Encoding of High Frequencies 1,2 3 1 Min Huang , Maxim Volgushev *, Fred Wolf * 1 Max-Planck-Institute for Dynamics and Self-Organization, Bernstein Center for Computational Neuroscience, and Faculty of Physics, Georg August University School of ¨ Science (GAUSS), Gottingen, Germany, 2 State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China, 3 Department of Psychology, University of Connecticut, Storrs, Connecticut, United States of America Abstract Generation of action potentials (APs) is a crucial step in neuronal information processing. Existing biophysical models for AP generation almost universally assume that individual voltage-gated sodium channels operate statistically independently, and their avalanche-like opening that underlies AP generation is coordinated only through the transmembrane potential. However, biological ion channels of various types can exhibit strongly cooperative gating when clustered. Cooperative gating of sodium channels has been suggested to explain rapid onset dynamics and large threshold variability of APs in cortical neurons. It remains however unknown whether these characteristic properties of cortical APs can be reproduced if only a fraction of channels express cooperativity, and whether the presence of cooperative channels has an impact on encoding properties of neuronal populations. To address these questions we have constructed a conductance-based neuron model in which we continuously varied the size of a fraction p of sodium channels expressing cooperativity and the strength of coupling between cooperative channels l. We show that starting at a critical value of the c