Berlin 2008 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 3: Neuronal Systems
BP 3.6: Vortrag
Montag, 25. Februar 2008, 15:45–16:00, C 243
Neuronal Avalanches in Networks with Short-Term Synaptic Plasticity — •Anna Levina1,2,3, J. Michael Herrmann1,4, and Theo Geisel1,3,4 — 1BCCN Göttingen — 2GK “Identification in Mathematical Models” — 3MPI for Dynamics and Self-Organization — 4Göttingen University, Dept. of Physics, Bunsenstr. 10, Göttingen
Critical avalanches of neural activity have been identified analytically in globally coupled networks of spiking neurons and were observed subsequently in neurophysiological recordings in cortical slices. While in previous models a fine-tuning of the connectivity parameters was required, we recently showed that the biologically well-established activity-dependent dynamics of the synaptic efficacies provides a possible mechanism for the self-organized criticalization of the neuronal dynamics.
The present work is based on a realistic model of short-term plasticity that includes both facilitation and depression of the synaptic efficacies. In a simplified model that uses depression only, the critical regime is reached by a second-order phase transition, where the critical phase is characterized by a stable balance of neural activity and synaptic depression. We show here that the incorporation of synaptic facilitation entails a first-order transition from the sub-critical regime into the extended critical parameter range. The results are obtained by a stochastic mean-field analysis and are related to numerical experiments by finite-size scaling of the critical distribution. Furthermore, we discuss effects of non-trivial connectivity structure, and neural properties such as leakage and long-term potentiation of the synaptic strengths.