  Inferring the presence of critical dynamics from continuous measure- ments is
a challenging problem. We solve this problem by showing that continuous
narrowband dynamics from a critical system exhibit qualita- tively differing
behaviors which depend on the universality class; we term each region of
critical avalanche parameters which generates qualitatively constant behavior a
meta-universality class. This theoretical observation allows us to infer
membership of a given meta-universality class and thus yields a robust test for
criticality. We validate these theoretical predic- tions in simulations and
provide unequivocal evidence for criticality in the human brain on the basis
electrophysiological recordings.
