Fig. 5.

A) Percent variance explained by the first and the second principal component for all subjects and breathing conditions. Note the different scaling of the y-axis for the first and the second PC. B) Normalized first principal component of normal breathing for all subjects. C) Average of the first principal component over all subjects for normal breathing, deep breathing and breath-holds. D-F) Magnitude of field fluctuations as measured by the first principal component scaled by the difference between maximum and minimum values of the corresponding projection time-course. The plots show the mean (solid line) and the range (vertical bars) over all subjects, for normal breathing (D), deep breathing (E) and breath-holds (F).