Fig. 2

Recruitment of the LC during both tasks and associations with pupil responses. A Whole-brain and LC responses to the perceptual switches during the visual perceptual rivalry task. Sagittal, coronal, and axial views [MNI coordinates: (− 4 − 37 −21 mm)]. The images at the top show the whole-brain results using significance for a threshold of p < 0.05 FDR-corrected (t > 2.16) over the group average brain structural image coregistered to the MNI space. Insets at the bottom show the LC probabilistic template (blue) created based on individual LC masks and the significant activation detected within this mask (dark red). B Whole-brain and LC responses to the target sound during the auditory salience detection task. Sagittal, coronal, and axial views [MNI coordinates: (− 4 − 34 −21 mm)]. The images at the top show the whole-brain results using significance for a threshold of p < 0.05 FDR-corrected (t > 2.33) over the group average brain structural image coregistered to the MNI space. Insets at the bottom show the LC probabilistic template (blue) and the significant activation detected within this mask (dark red). The legend shows the t-values associated with color maps. C A representative example of the pupil dilation in response to the perceptual switches during the visual perceptual rivalry task in one participant. D A representative example of the pupil dilation in response to the standard and target sounds during the auditory salience detection task in the same subject as in panel C. E Minimum and maximum pupil size before and after the perceptual switches during the visual perceptual rivalry task. Maximum pupil size was significantly higher than the minimum (N = 32, p < 0.0001). Arbitrary units (AU) of the pupil size in the figures C, D and E are based on pixel number following proprietary algorithms application yet do not correspond exactly to pixel number. F Mean ratio of the pupil size in the perceptual rivalry task. The mean ratio of pupil size was computed as the change in the pupil diameter from before to after the perceptual switches. G Association between LC activity during visual perceptual rivalry task and mean ratio of pupil size in response to the perceptual switches. The association was not significant (Pearson’s correlation r = −0.201, P = 0.29). H Mean ratio of pupil size in response to standard sound and target sound during the auditory salience detection task. The mean ratio of pupil size was computed as the change in the pupil diameter from before to after the auditory stimulus presentation. The change in pupil size was significantly higher for target versus standard sound (N = 27, p < 0.0001). I Association between LC activity during auditory salience detection task and mean ratio of pupil size in response to the target sound. We found a significant positive Pearson’s correlation (r = 0.4, P = 0.03)