Pupil size reflects activation of subcortical ascending arousal system nuclei during rest

Neuromodulatory nuclei that are part of the ascending arousal system (AAS) play a crucial role in regulating cortical state and optimizing task performance. Pupil diameter, under constant luminance conditions, is increasingly used as an index of activity of these AAS nuclei. Indeed, task-based functional imaging studies in humans have begun to provide evidence of stimulus-driven pupil-AAS coupling. However, whether there is such a tight pupil-AAS coupling during rest is not clear. To address this question, we examined simultaneously acquired resting-state fMRI and pupil-size data from 74 participants, focusing on six AAS nuclei: the locus coeruleus, ventral tegmental area, substantia nigra, dorsal and median raphe nuclei, and cholinergic basal forebrain. Activation in all six AAS nuclei was optimally correlated with pupil size at 0- to 2-second lags, suggesting that spontaneous pupil changes were almost immediately followed by corresponding BOLD-signal changes in the AAS. These results ..., This dataset contains resting-state fMRI data and simultaneous pupil recordings for 72 individuals across two sessions of 5 minutes.
MRI data
MRI data were acquired using a Siemens MAGNETOM Prisma 3T MR scanner. All images (functional and structural) have been defaced for anonymity purposes.

functional EPI images (150) per session (ses-day1, ses-day2), 5 minutes resting-state (no task).

T2*-weighted BOLD images were recorded using a customized multi-echo EPI sequence with ascending slice acquisition (58 axial slices; TR = 2 s; TE = 14.4, 39.1 ms; partial Fourier = 6/8; GRAPPA acceleration factor = 2; multiband acceleration factor = 2; flip angle = 65°; slice matrix size 104 x 104 mm; slice thickness = 2.0 mm; FOV: 208 x 208 mm; slice gap = 0; bandwidth: 2090 Hz/px; echo spacing: 0.56 ms). 
the only preprocessing carried out on the functional EPI images is that these images have been realigned to the first functional image (using the realignment parameters, see: nuisance regressors 26–...,