Spontaneous fluctuations of pupil size and brain rhythms co-vary at rest
Christian Keitel1, Gregor Thut1, Anne Keitel1, Joachim Gross1,2; 1University of Glasgow, 2University of Münster
Cortical brain activity underlies a number of varying non-cortical authorities. These can act to regulate cortical excitability and thus bias our momentary perception, cognition, and in consequence, our behavioural performance. One such global influence arises from the reticular activating system, specifically the locus-coeruleus-norepiphrenergic (LC-NE) circuit that controls arousal. This circuit is normally difficult to access directly with neuroimaging but is linked with changes in pupil size. We have exploited this link in resting-state MEG recordings (7 min) to simultaneously assess LC-NE activity via concurrent eye tracking. In a source-level whole-brain analysis we correlated local power envelopes of rhythmic activity in canonical frequency bands (2 – 128 Hz) with slow-varying (< 1 Hz) spontaneous fluctuations in pupil size (diameter). Our approach uncovered a range of correspondences across frequency bands. The most pronounced effect was a correlation of oscillatory power expanding across alpha-beta frequency ranges (peak at 16 Hz) with an occipito-parietal topography, implicating LC-NE in the regulation of visual processing. Our findings therefore describe how slow spontaneous variations in momentary arousal (LC-NE) may bias relatively fast-paced rhythmic activity in cortex, and possibly its function in perception and cognition.
Topic Area: PERCEPTION & ACTION: Vision