domingo, abril 20, 2008

Itinerância caótica com outro nome

Ler e mandar para Juliana Dias. Verificar as referências, especialmente a do New Journal of Physics. Ver também:

Neuroscience: States of mind: Nature 425, 912-913 doi : 10.1038/425912a

Neural networks with transient state dynamics

Claudius Gros 2007 New J. Phys. 9 109 doi: 10.1088/1367-2630/9/4/109 Help

Claudius Gros1
Institute of Theoretical Physics, J.W. Goethe University Frankfurt, 60438 Frankfurt, Germany

Abstract. We investigate dynamical systems characterized by a time series of distinct semi-stable activity patterns, as they are observed in cortical neural activity patterns. We propose and discuss a general mechanism allowing for an adiabatic continuation between attractor networks and a specific adjoined transient-state network, which is strictly dissipative. Dynamical systems with transient states retain functionality when their working point is autoregulated—avoiding prolonged periods of stasis or drifting into a regime of rapid fluctuations. We show, within a continuous-time neural network model, that a single local updating rule for online learning allows simultaneously (i) for information storage via unsupervised Hebbian-type learning, (ii) for adaptive regulation of the working point and (iii) for the suppression of runaway synaptic growth. Simulation results are presented; the spontaneous breaking of time-reversal symmetry and link symmetry are discussed.

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