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Arousal, eye tracking, pupillometrie, resting state fMRI, vigilance
Abstract:
Resting state functional magnetic resonance imaging (rs-fMRI) is
increasingly applied for the development of functional biomarkers in
brain disorders. Recent studies have revealed spontaneous vigilance
drifts during the resting state, involving changes in brain activity and
connectivity that challenge the validity of uncontrolled rs-fMRI
findings. In a combined rs-fMRI/eye tracking study, the pupil size of 32
healthy subjects after 2 h of sleep restriction was recorded as an
indirect index for activity of the locus coeruleus, the brainstem's
noradrenergic arousal center. The spontaneous occurrence of pupil
dilations, but not pupil size per se, was associated with increased
activity of the salience network, thalamus and frontoparietal regions.
In turn, spontaneous constrictions of the pupil were associated with
increased activity in visual and sensorimotor regions. These results
were largely replicated in a sample of 36 healthy subjects who did not
undergo sleep restriction, although in this sample the correlation
between thalamus and pupil dilation fell below whole-brain significance.
Our data show that spontaneous pupil fluctuations during rest are indeed
associated with brain circuitry involved in tonic alertness and
vigilance. Pupillometry is an effective method to control for changes in
tonic alertness during rs-fMRI. (C) 2016 Elsevier Inc. All rights
reserved.
