Hongjian He1,2, David D. Shin2,
Thomas T. Liu2
1Physics Department, Zhejiang
University, Hangzhou, Zhejiang, China; 2Center for functional MRI,
UC San Diego, La Jolla, CA, United States
Removal
of the global mean signal is a common step in the processing of resting-state
fMRI data. However, its usage can produce spurious negative correlations. .
Here we propose the use of BOLD signal fluctuations in the large draining
veins as an alternative to the global mean signal that does not force the
existence of negative correlations. We show that signals from two vein
regions (sagittal sinus and great vein of Galen) are significantly correlated
with the global mean signal and may therefore represent a useful alternative
for the analysis of resting-state fMRI studies.