The human cortex is never at rest but in a state of sparse and noisy neural activity  . It has been conjectured that such a state is best described as a critical dynamical process -- whose nature is still not fully understood -- where scale-free avalanches of activity emerge at the edge of a synchronization phase transition. Using a simple model of coupled excitable oscillators , we rule out standard phase transitions to explain the emergence of collective oscillations, as they do not suffice to explain current experimental evidence. Conversely, we uncover a novel hybrid-type of synchronization transition displaying a very-rich dynamical repertoire supporting all key empirical observations, including scale-free avalanches , marginal coherence, and bistability .
The human cortex is never at rest but in a state of sparse and noisy neural activity that can be detected at broadly diverse resolution scales . It has been conjectured that such a state is best described as a critical dynamical process -- whose nature is still not fully understood -- where scale-free avalanches of activity emerge at the edge of a phase transition. In particular, some works suggest that this is most likely a synchronization transition, separating synchronous from asynchronous phases. Here, by investigating a simplified model of coupled excitable oscillators describing the cortex dynamics at a mesoscopic level, we investigate the possible nature of such a synchronization phase transition. Within our modeling approach, we conclude that -- in order to reproduce all key empirical observations, such as scale-free avalanches and bistability, on which fundamental functional advantages rely -- the transition to collective oscillatory behavior needs to be of an unconventional hybrid type, with mixed features of type-I and type-II excitability, opening the possibility for a particularly rich dynamical repertoire .
A
that can be detected at broadly diverse resolution scales
D
synchronization
R
Using a simple
In particular, some works suggest that this is most likely a synchronization transition, separating synchronous from asynchronous phases. Here, by investigating a simplified
R
, we rule out standard phase transitions to explain the emergence of collective oscillations, as they do not suffice to explain current experimental evidence. Conversely, we uncover a novel hybrid-type of synchronization transition displaying a very-rich dynamical repertoire supporting
describing the cortex dynamics at a mesoscopic level, we investigate the possible nature of such a synchronization phase transition. Within our modeling approach, we conclude that -- in order to reproduce
R
including
such as
R
, marginal coherence, and bistability
and bistability, on which fundamental functional advantages rely -- the transition to collective oscillatory behavior needs to be of an unconventional hybrid type, with mixed features of type-I and type-II excitability, opening the possibility for a particularly rich dynamical repertoire