Current biology : CB
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Current biology : CB · Dec 2011
Cortical hypersynchrony predicts breakdown of sensory processing during loss of consciousness.
Intrinsic cortical dynamics modulates the processing of sensory information and therefore may be critical for conscious perception. We tested this hypothesis by electroencephalographic recording of ongoing and stimulus-related brain activity during stepwise drug-induced loss of consciousness in healthy human volunteers. We found that progressive loss of consciousness was tightly linked to the emergence of a hypersynchronous cortical state in the alpha frequency range (8-14 Hz). ⋯ The antagonistic relation between the late sensory response and ongoing alpha activity held for constant drug levels on the single-trial level. Specifically, the late response component was negatively correlated with the power and long-range coherence of ongoing frontal alpha activity. Our results suggest blocking of intracortical communication by hypersynchronous ongoing activity as a key mechanism for the loss of consciousness.