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quinta-feira, julho 09, 2009

Avalanches neuronais e faixa dinâmica decolando!





Woodrow L. Shew1, Hongdian Yang1;2, Thomas Petermann1, Rajarshi Roy2, Dietmar Plenz1
1Section on Critical Brain Dynamics, NIMH, NIH Bethesda, MD, 20892
2Institute for Physical Science and Technology, University of Maryland, College Park, MD, 20742



Model studies predict that aspects of information processing would be optimal at criticality (e.g. [1, 8, 13]), but experimental support of these ideas is lacking. Our aim here was to provide an answer to these questions based on comparisons of spontaneous activity and stimulus-evoked activity measured in the same brain tissue. Specifically, we test a prediction by Kinouchi and Copelli [8] that neuronal networks at criticality are sensitive to the largest range of stimuli, i.e. they have maximum dynamic range.



In summary, we used experiments and a model to demonstrate a strong connection between the spontaneous activity generated by a neuronal network and its ability to process external stimuli. When the spontaneous activity indicated that the network state was closest to criticality, i.e. when k was closest to one, the dynamic range of the network was maximum. This result supports previous predictions from modelling studies [8].



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