Collective plasticity and individual stability in cultured neuronal networks

Cultured neuronal networks generate spontaneous activity in the form of synchronized bursting events (SBEs)—short time events during which most of the recorded neurons fire rapidly. Each neuron in the SBE has its own temporal firing rate pattern. It has been shown that a large network can exhibit several SBE sub-groups, each with its own characteristic spatio-temporal pattern of activity. In this work we address the question: what distinguishes one sub-group of SBEs from another? We show that in each SBE type the neurons fire at different delays relative to one another and that in different SBEs the firing rate function of each neuron remains the same. Modeled neurons in simulated networks with non-homogeneous architecture could exhibit only one of these two characteristics, but not both. We propose that incorporating mechanisms of global network regulation, for instance in the form of glia, might lead to more realistic modeling consistent with our results. r 2006 Elsevier B.V. All rights reserved.