Temporal Organization of Neuronal Avalanches at Criticality

Bursty dynamics characterizes many physical systems. In neuronal networks the near synchronous firing of many neurons gives rise to the so-called neuronal avalanches, a collective phenomenon that is a key feature of the resting brain activity. Experiments at all spatial scales have evidenced that neuronal avalanche sizes and durations follow power law distributions, a typical feature of systems at criticality. Yet, avalanche dynamics in neuronal systems remain poorly understood. In this talk I will focus on the relationship between criticality and temporal structure of avalanches in cortex slice cultures.
I will first show that waiting time distributions for avalanches follow a common non-monotonic behavior, featuring a power law at short (< 1s) timescales followed by a local minimum and an exponential tail(Phys.Rev.Lett.108,2012). Using numerical simulations, I'll demonstrate that this peculiar behavior arises from the alternation of two different network states, the up and down-state, and that the specific temporal organization of neuronal avalanches is closely related to the criticality of the system. Finally, I'll discuss the dynamical relationship between avalanches and waiting times, and its connection with excitatory and inhibitory network features(Chaos,27,2017).