Article Figures & Data
Figures
- Figure 1.
Pupil size and alpha-activity fluctuations are correlated. A, Spectrogram of Oz channel during the whole duration of the gaze fixation period. Black parallel lines define the alpha band of an individual subject (subject 2). The mean normalized power in the alpha band is shown (black trace). B, Normalized pupil diameter during fixation period. Raw pupil trace (blue), low-frequency pupil component (brown), and high-frequency pupil component (purple). C, Grand average of power spectrum of parietal–occipital electrodes (n = 16 subjects). Inset, Topographical distribution of mean alpha power. D, Mean amplitude of the high-frequency component of the pupil dynamic versus mean alpha power and the corresponding linear fit (red) averaged across all subjects (Extended Data Fig. 1-1).
- Figure 2.
Pupil size peaks and troughs are associated with increases and decreases of alpha power. A, High-frequency pupil diameter dynamic during the task. Pupil amplitude peaks (light green) and troughs (dark green). B, Average power spectrum of parietal–occipital electrodes (see Materials and Methods) for epochs centered at peak (light green) and trough (dark green) of pupil diameter (n = 16; shadows correspond to SEM). Inset, Spatial distribution of the alpha band in the pupil peak (light green) and pupil trough (dark green) conditions.
- Figure 3.
Alpha power is modulated around peaks and troughs in pupil diameter. A, Time-resolved normalized power spectrum of the same electrodes in Figure 2B centered around the peak (left) and trough (right) of pupil diameter. Color bar represents the relative change in respect to the whole epoch. B, Alpha power in time related to the peak (left) and trough (right) of pupil diameter. Normalized pupil size (red), first derivative (black), and center of the event (segmented line). Shadows represent SEM. C, Spatial distribution of the difference in alpha band between peak and trough condition. Analysis windows were set from −0.6 to −0.2 s (left; B, yellow shadow) and from 0.2 to 0.6 s (right; B, purple shadow). p < 0.001 in a cluster-based permutation test (white stars). Color bar represents the relative change with respect to the whole epoch. D, Polar histogram of alpha power in relation to high-frequency pupil phase. Red line represents the mean resultant vector across the whole trial of all subjects (Extended Data Fig. 3-1).
Extended Data
Figure 1-1
Individual correlation between pupil size and alpha amplitude. Left, Traces in light red correspond to each individual correlation between the pupil size deciles and the corresponding alpha amplitude at Oz location. Gray circles correspond to the averages of the decile used to calculate the correlations. Red line and black circles are the same averaged values shown in Figure 1D. Right, Black squares correspond to individual r2 and p value results from each individual correlation. Download Figure 1-1, TIF file.
Figure 3-1
Normalized cross-correlation between pupil size and alpha power. A, Traces in gray correspond to each individual cross-correlation between the time course of the pupil size signal and the alpha power at occipital electrodes centered at peak pupil size. Green line represents the mean of all subjects (left). Same analysis as in left panel but centered at the trough of pupil size (right). B, Same as A, but for flipped EEG signal. Download Figure 3-1, TIF file.
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