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Perspective ARTICLE

This article is part of a Research Topic

Inhibitory “noise”

Unité de Neurosciences, Infomation et Complexité, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France

Cortical neurons in vivo may operate in high-conductance states, in which the major part of the neuron’s input conductance is due to synaptic activity, sometimes several-fold larger than the resting conductance. We examine here the contribution of inhibition in such high-conductance states. At the level of the absolute conductance values, several studies have shown that cortical neurons in vivo are characterized by strong inhibitory conductances. However, conductances are balanced and spiking activity is mostly determined by fluctuations, but not much is known about excitatory and inhibitory contributions to these fluctuations. Models and dynamic-clamp experiments show that, during high-conductance states, spikes are mainly determined by fluctuations of inhibition, or by inhibitory “noise”. This stands in contrast to low-conductance states, in which excitatory conductances determine spiking activity. To determine these contributions from experimental data, maximum likelihood methods can be designed and applied to intracellular recordings in vivo. Such methods indicate that action potentials are indeed mostly correlated with inhibitory fluctuations in awake animals. These results argue for a determinant role for inhibitory fluctuations in evoking spikes, and do not support feed-forward modes of processing, for which opposite patterns are predicted.

Keywords:

spike-triggered average, conductance, cerebral cortex, dynamic-clamp, computational models

Citation:

Destexhe A (2010). Inhibitory “noise”. Front. Cell. Neurosci. 4:9. doi: 10.3389/fncel.2010.00009

Received:

18 February 2010;

Paper pending published:

10 March 2010;

Accepted:

13 March 2010;

Published online:

31 March 2010.

Edited by:

Yehezkel Ben-Ari, INSERM, France

Reviewed by:

Dominique Debanne, Université de la Méditerranée, France

© 2010 Destexhe. This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.

*Correspondence:

Alain Destexhe, Unité de Neurosciences, Infomation et Complexité, Bat 33, Centre National de la Recherche Scientifique, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France. e-mail: destexhe@unic.cnrs-gif.fr