Brain Dynamics at the Edge of Chaos
Dynamical systems (basically all of them) display a wide repertoire of dynamics when tuned close to criticality (https://en.wikipedia.org/wiki/Critical_phenomena). In this range, organized patterns of activity emerge, close to those that we find when looking at statistical dependencies between time series recording (at least partially) brain activity.

Long range correlations also emerge in this phase.

So, it's true that dynamical models tuned close to criticality better fit brain activity. On the other hand saying that "brain activity is critical" is a logical fallacy, since we are giving to the modelled system properties of the model.

(chaos is a close concept, stressing the dependency on initial conditions, but in this case I think that criticality is more relevant).

See, among other things, this scientific yet accessible paper

Beggs, J. M., &amp; Timme, N. (2012). Being Critical of Criticality in the Brain. Frontiers in Physiology, 3. doi:10.3389/fphys.2012.00163

https://www.frontiersin.org/articles/10.3389/fphys.2012.00163/full