Quantitative Characterization of Vascular Non-Linearities in BOLD fMRI
van Gelderen P, Duyn J, de Zwart J, Jansma J
National Institutes of Health
Studies of the BOLD response to varying neuronal activity have reported some degree of non-linearity, but are not in quantitative agreement. To some extent, this is due to confounding neuronal effects related to closely spaced stimuli. In this work, we used the m-sequence method with gapped sub-second visual stimuli to characterize the impulse response with minimal neuronal contribution. Results obtained from human fMRI at 3.0 T show a small but significant non-linearity in the form of temporal dispersion, consistent with a lingering blood volume (balloon) effect.