Abstract #4643

Probing the Signal Physiology of Resting-State fMRI at High Frequencies using Hypocapnia

Abraham Dominguez Hernandez¹, Arpad Zolyomi², Arvind Caprihan³, Kishore Vakamudi⁴, Stephen R Dager⁵, and Stefan Posse⁴

¹Neurology, University of New Mexico, Albuquerque, NM, United States, ²Anesthesiology, University of New Mexico, Albuquerque, NM, United States, ³The Mind Research Network, Albuquerque, NM, United States, ⁴Neurology, Physics and Astronomy, University of New Mexico, Albuquerque, NM, United States, ⁵Radiology, University of Washington, Seattle, WA, United States

We investigate the dependence of high frequency signal changes on decreases in global blood flow using hyperventilation induced hypocapnia, which substantially alter the amplitude and time course of the hemodynamic response function (HRF) with only minor changes in neural activation levels. We also investigate the sensitivity of multi-band-EPI and a prototype ultra-high-speed multi-band-EVI (MB-EVI) sequence for detecting high frequency correlations. In the first subject, an increase in high frequency correlations during hypocapnia was detected in MB-EPI and MB-EVI. These studies suggest that high frequency signals changes may be mediated by vascular physiology, but movement related artifacts cannot be excluded.

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