By Bradley Voytek (La Jolla, CA).

Perception, action, and cognition depend upon coordinated neural activity. This coordination operates within noisy, distributed neural networks potentially poised on the edge of criticality. These networks change with development, aging, and disease. Extensive field potential and EEG research shows that neural oscillations interact with neuronal spiking, which has been proposed to be a mechanism for implementing dynamic coordination between brain regions, placing oscillations at the forefront of neuroscience research. Our work challenges our definitions of neural oscillations and criticality. Beginning from basic theory and modeling, we show that apparently critical dynamics arise naturally because of the double exponential form of the postsynaptic currents that give rise to the LFP and EEG. Making use of a combination of neural modeling and a breadth of empirical data—spanning human iPSC-derived cortical organoids, animal electrophysiology, invasive human EEG, and large-scale data mining—we show that this aperiodic activity is dynamic, changes rapidly with task demands, and physiologically reflects the relative contributions of excitatory and inhibitory postsynaptic currents driving the LFP.

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