Speaker: Dr. J.P. Thivierge Department of Psychological and Brain Sciences, Indiana University, USA The Role of Synchronized Activity in Healthy and Pathological Neuronal Circuits Neurons have a natural tendency to synchronize their activity, with important implications for our thoughts and actions. For instance, a neural code based on synchrony is responsible for conscious attention to stimuli and movement preparation, as well as the maintenance of task-relevant representations in active memory. Further, several neuropathological diseases are accompanied by a deterioration of synchronization. Despite its importance in the brain, the factors driving the emergence of synchronization remain largely unknown. In addition, the loss – and potential recovery – of synchronized neural activity following neural disease and injury is poorly characterized. In this talk, I will argue that these questions can be addressed to a large extent in reduced preparations of neural circuits. I will describe in vitro recordings performed with multielectrode arrays (MEAs), a well-established model for studying neural interactions across large populations of cells at a high temporal resolution. I will show that networks of primary cortical neurons develop and maintain highly structured bursts of activity (termed “network spikes”) extending both in time and across cells. Further, I will argue that neural activation propagates in a non-egalitarian manner across these networks. In fact, a subpopulation of “core cells” plays a central role in the relay of neural signals between otherwise isolated regions of the array, with direct implications for the functionality of neural circuits. Finally, I will describe pharmacological interventions that alter neural synchronization, disrupting the relay of neural activity. Taken together, these results are aimed at expanding our understanding of functional interactions in healthy cortical circuits and open new areas of exploration into the effects of pharmacological interventions on neural functionality.