Abstract #0283

Contrast mechanisms in vessel-scale human fMRI: Ultra-slow post-stimulus “ringing” oscillations in cortical arteries

Sébastien Proulx^1,2, Divya Varadarajan^1,2, Jacob Duckworth³, Zhangxuan Hu^1,2, Jingyuan Chen^1,2, Grant Hartung^1,2,4, David Kleinfeld^3,5, and Jonathan R. Polimeni^1,2,6

¹Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ²Department of Radiology, Harvard Medical School, Boston, MA, United States, ³Department of Physics, University of California San Diego, La Jolla, CA, United States, ⁴Computational Mechanics, Technical University of Darmstadt, Darmstadt, Germany, ⁵Department of Neurobiology, University of California San Diego, La Jolla, CA, United States, ⁶Harvard-MIT Program in Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States

Synopsis

Keywords: Task/Intervention Based fMRI, Blood vessels

Motivation: In-vivo microscopy of brain hemodynamics have observed resonance phenomena in pial arteries in mouse cerebral cortex, however similar observations in human fMRI are anecdotal. Vessel-scale fMRI has the potential to reconcile these observations.

Goal(s): Characterize arterial resonance phenomena in human pial vessels.

Approach: Vessel-scale fMRI sensitive to blood velocity and vessel diameter changes to track responses of individual pial vessels to visual stimulation.

Results: Reductions in inflow enhanced signal are seen in many arterial responses, suggesting a reduced velocity corresponding to increased vessel diameters. Responding vessels exhibit “post-stimulus ringing”, i.e., slow oscillations (~0.1Hz) phase-locked to stimulus presentation, after the main response.

Impact: We demonstrate a post-stimulus ringing phenomenon in vessel-scale fMRI responses in individual cortical arteries when responding to visual stimulation. This suggests a trial-locked oscillation that is consistent with observations of arterial resonance seen in in-vivo microscopy studies.

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