Neural network mechanisms underlying stimulus driven variability reduction

Deco, Gustavo; Hugues, Etienne

doi:http://dx.doi.org/10.1371/journal.pcbi.1002395

Neural network mechanisms underlying stimulus driven variability reduction

License

Citation

Deco G, Hugues E. Neural network mechanisms underlying stimulus driven variability reduction. PLoS Computational Biology. 2012;8(3):1-10. DOI: 10.1371/journal.pcbi.1002395

Abstract

It is well established that the variability of the neural activity across trials, as measured by the Fano factor, is elevated. This/nfact poses limits on information encoding by the neural activity. However, a series of recent neurophysiological experiments/nhave changed this traditional view. Single cell recordings across a variety of species, brain areas, brain states and stimulus/nconditions demonstrate a remarkable reduction of the neural variability when an external stimulation is applied and when/nattention is allocated towards a stimulus within a neuron’s receptive field, suggesting an enhancement of information/nencoding. Using an heterogeneously connected neural network model whose dynamics exhibits multiple attractors, we/ndemonstrate here how this variability reduction can arise from a network effect. In the spontaneous state, we show that the/nhigh degree of neural variability is mainly due to fluctuation-driven excursions from attractor to attractor. This occurs when,/nin the parameter space, the network working point is around the bifurcation allowing multistable attractors. The application/nof an external excitatory drive by stimulation or attention stabilizes one specific attractor, eliminating in this way the/ntransitions between the different attractors and resulting in a net decrease in neural variability over trials. Importantly, nonresponsive/nneurons also exhibit a reduction of variability. Finally, this reduced variability is found to arise from an increased/nregularity of the neural spike trains. In conclusion, these results suggest that the variability reduction under stimulation and/nattention is a property of neural circuits.