Abstract
Brain criticality has emerged as a rapidly growing focus of research among neuroscientists and physicists. The latest experimental evidence suggests that even isolated neurons display signs of criticality. Using a stochastic type-I parametrization of the Hodgkin-Huxley model, we investigate the origin of these critical dynamics. We show that the model adequately approximates the experimentally observed behavior, as it reproduces the qualitative relationship between the critical state and both the applied external stimulation and the spiking rate. External white noise further enhances any pre-existing critical intermittency but cannot by itself toggle the system into a critical state. The emergence of the critical state is conditional on the system's proximity to its spiking bifurcation point, and any divergence from it results in the abolition of the dynamics. We treat the neuronal membrane as a complex self-organizing system composed of interacting ion channels and propose that the observed dynamics result from an almost critical state.