In collaboration with Claude Bedard (postdoc in my laboratory), we have recently investigated how to incorporate the effect of charge displacement into cable equations. When ion channels open or close, the flow of ions depends on the concentrations at either side of the membrane, and in all cable equations considered so far, this displacement of charges was considered as instantaneous. However, as seen above for modeling of LFPs (Section 1.3), charge displacement is not instantaneous, and may lead to important effects such as high-frequency filtering of LFPs. We incorporated this effect into cable equations, in order to determine its influence on several important properties of the neuron, such as the attenuation with distance and post-synaptic summation. We obtained a more accurate electrical description of the neuron for high frequencies, as well as predictions that can be tested experimentally.
A paper was accepted recently [1] where we showed that such modified cable equations are more accurate to model fast-frequency phenomena in neurons. We are presently pursuing this approach to determine possible consequences on integrative properties.
[1] Bedard, C. and Destexhe, A. A modified cable formalism for modeling neuronal membranes at high frequencies. Biophys. J. 94: 1133-1143, 2008 (see abstract)
Unité de Neurosciences, Information & Complexité
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