Jaemin Shin1, Richard Cameron Craddock2, Helen Mayberg3, Xiaoping Hu1
1Biomedical Engineering, Georgia Tech / Emory Univ, Atlanta, GA, USA; 2Electrical and Computer Engineering, Georgia Tech, Atlanta, GA, USA; 3Psychiatry and Behavioral Sciences, Emory University, Atlanta, GA, USA
Physiological fluctuations due to respiration are the dominant source of confounding variability in BOLD fMRI. Recently low-frequency fluctuations in the depth and the rate of respiration have been identified as a source of long-term respiration effects. Respiration volume per time (RVT) and respiration response function (RRF) have been proposed as global models of respiration effects. The global models implicitly assume that the respiration effects are space-invariant and subject-invariant. We examined spatial and subject variability of long-term respiration effects by clustering the voxel-specific physiological impulse response functions and found that substantial variability in both regards exists.