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Neuroimage. 2016 Apr 15;130:293-305. doi: 10.1016/j.neuroimage.2015.12.034. Epub 2015 Dec 24.

Progression to deep sleep is characterized by changes to BOLD dynamics in sensory cortices.

Author information

1
Center for Mind/Brain Sciences (CIMeC), University of Trento, Italy.
2
Department of Neurology and Brain Imaging Center, Goethe University, Frankfurt, Germany.
3
Department of Neurology, University Hospital Schleswig Holstein, Kiel, Germany; Department of Neurology and Brain Imaging Center, Goethe University, Frankfurt, Germany.
4
Center for Mind/Brain Sciences (CIMeC), University of Trento, Italy. Electronic address: uri.hasson@unitn.it.

Abstract

Sleep has been shown to subtly disrupt the spatial organization of functional connectivity networks in the brain, but in a way that largely preserves the connectivity within sensory cortices. Here we evaluated the hypothesis that sleep does impact sensory cortices, but through alteration of activity dynamics. We therefore examined the impact of sleep on hemodynamics using a method for quantifying non-random, high frequency signatures of the blood-oxygen-level dependent (BOLD) signal (amplitude variance asymmetry; AVA). We found that sleep was associated with the elimination of these dynamics in a manner that is restricted to auditory, motor and visual cortices. This elimination was concurrent with increased variance of activity in these regions. Functional connectivity between regions showing AVA during wakefulness maintained a relatively consistent hierarchical structure during wakefulness and N1 and N2 sleep, despite a gradual reduction of connectivity strength as sleep progressed. Thus, sleep is related to elimination of high frequency non-random activity signatures in sensory cortices that are robust during wakefulness. The elimination of these AVA signatures conjointly with preservation of the structure of functional connectivity patterns may be linked to the need to suppress sensory inputs during sleep while still maintaining the capacity to react quickly to complex multimodal inputs.

PMID:
26724779
PMCID:
PMC4819724
DOI:
10.1016/j.neuroimage.2015.12.034
[Indexed for MEDLINE]
Free PMC Article

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