Identification and Dynamics of Spontaneous Burst Initiation Zones in Unidimensional Neuronal Cultures

1 Departments of Physics of Complex Systems and 2 Neuroscience, The Weizmann Institute of Science, Rehovot, Israel Submitted 8 September 2006; accepted in final form 3 February 2007 Spontaneous activity is typical of in vitro neural networks, often in the form of large population bursts. The origins of this activity are attributed to intrinsically bursting neurons and to noisy backgrounds as well as to recurrent network connections. Spontaneous activity is often observed to emanate from localized sources or initiation zones, propagating from there to excite large populations of neurons. In this study, we use unidimensional cultures to overcome experimental difficulties in identifying initiation zones in vivo and in dissociated two-dimensional cultures. We found that spontaneous activity in these cultures is initiated exclusively in localized zones that are characterized by high neuronal density but also by recurrent and inhibitory network connections. We demonstrate that initiation zones compete in driving network activity in a winner-takes-most scenario. Present address and address for reprint requests and other correspondence: O. Feinerman, Memorial Sloan Kettering Cancer Center, 415 E 68th St., Rm: 1419, New York, NY 10021 (E-mail: feinermo{at}mskcc.org )