“DynamicalSystems ” — 2004/3/4 — page #393 A Mathematical Approach towards the Issue of Synchronization in Neocortical Neural Networks

When interaction among regularly spiking neurons is simulated, using mea-sured cortical response profiles as experimental input, besides complex network-effects dominated behavior, embedded periodic behavior is observed. This is the starting point for our theoretical analysis of possible emergence of syn-chronized neocortical neuronal firing, where we start from the model that complex behavior, as observed in natural neural firing, is generated from such periodic behavior, lumped together in time. We address the question of how, during periods of quasistatic activity, different local centers of such behav-iors could synchronize, as has been postulated, e.g., by binding theory. It is shown that for synchronization, methods of self-organization are insuffi-cient: additional structure is needed. As a candidate for this task, thalamic input into layer IV is proposed, which, due to the layer’s recurrent architec-ture, may trigger macroscopically synchronized bursting among intrinsically non-bursting neurons, leading in this way to a robust neocortical synchro-nization paradigm. This collective behavior in layer IV is hyperchaotic and corresponds well with the characterizations obtained from in vivo time series measurements of cortical response to visual stimuli.