The resting brain is not resting - collective irregular dynamics in spiking networks

Ekkehard Ullner (University of Aberdeen)

The origin of the self-sustained brain activity in the resting state is not fully understood. We propose the collective irregular dynamics (CID) as a possible mechanism. Collective irregular dynamics (CID) is stochastic-like behavior on macroscopic scales.
We discuss the emergence of CID in random networks of spiking neurons with quasi-balanced activity. Our analysis is based on the computation of a suitable order parameter, typically used to characterize synchronisation phenomena.
A detailed investigation of the thermodynamic limit for fixed density of connections shows that the asymptotic regime is characterized by self-sustained irregular, macroscopic (collective) dynamics. As long as the connectivity is massive, this regime is found in many different setups. The irregularity of the collective dynamics is justified by the power spectra of the neural activity, a fractal-dimension analysis and standard synchronisation measures. As a result, we can conclude that CID is a true thermodynamic phase, intrinsically different from the standard asynchronous regime.