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Neuron. 2015 Oct 7;88(1):194-206. doi: 10.1016/j.neuron.2015.09.018.

Spontaneous Fluctuations and Non-linear Ignitions: Two Dynamic Faces of Cortical Recurrent Loops.

Author information

1
Institut National de la Santé et de la Recherche Médicale, U992, Cognitive Neuroimaging Unit, NeuroSpin Center, Saclay Center, 91191 Gif-sur-Yvette, France; Commissariat à l'Energie Atomique, Division of Life Sciences, Institute of BioImaging, NeuroSpin Center, 91191 Gif-sur-Yvette, France; Université Paris-Sud, Cognitive Neuroimaging Unit, 91405 Orsay Cedex, France.
2
Institut National de la Santé et de la Recherche Médicale, U992, Cognitive Neuroimaging Unit, NeuroSpin Center, Saclay Center, 91191 Gif-sur-Yvette, France; Commissariat à l'Energie Atomique, Division of Life Sciences, Institute of BioImaging, NeuroSpin Center, 91191 Gif-sur-Yvette, France; Université Paris-Sud, Cognitive Neuroimaging Unit, 91405 Orsay Cedex, France; Collège de France, Place Marcelin Berthelot, 75005 Paris, France.
3
Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel. Electronic address: rafi.malach@gmail.com.

Abstract

Recent human neurophysiological recordings have uncovered two fundamental modes of cerebral cortex activity with distinct dynamics: an active mode characterized by a rapid and sustained activity ("ignition") and a spontaneous (resting-state) mode, manifesting ultra-slow fluctuations of low amplitude. We propose that both dynamics reflect two faces of the same recurrent loop mechanism: an integration device that accumulates ongoing stochastic activity and, either spontaneously or in a task-driven manner, crosses a dynamic threshold and ignites, leading to content-specific awareness. The hypothesis can explain a rich set of behavioral and neuronal phenomena, such as perceptual threshold, the high non-linearity of visual responses, the subliminal nature of spontaneous activity fluctuations, and the slow activity buildup anticipating spontaneous behavior (e.g., readiness potential). Further elaborations of this unified scheme, such as a cascade of integrators with different ignition thresholds or multi-stable states, can account for additional complexities in the repertoire of human cortical dynamics.

PMID:
26447581
DOI:
10.1016/j.neuron.2015.09.018
[Indexed for MEDLINE]
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