Abstract #3726

Fast fMRI responses supported by inter-voxel variability of hemodynamic response functions

Jingyuan E. Chen^1,2, Jonathan R. Polimeni^1,2,3, Nina E. Fultz¹, Gary Glover⁴, and Laura D. Lewis^1,5

¹Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, ²Department of Radiology, Harvard Medical School, Boston, MA, United States, ³Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Cambridge, MA, United States, ⁴Radiology, Stanford University, Palo Alto, CA, United States, ⁵Biomedical Engineering, Boston University, Boston, MA, United States

In this abstract, we use very high-resolution fMRI to evaluate inter-voxel variability of hemodynamic response functions (HRF) elicited by a visual task. We show that HRFs exhibit wide variability across voxels, with a subset of HRFs occurring at temporal scales much faster than the canonical HRF, which we consider as one mechanism that underlie fast neural-activity-related dynamics. Influence of spatial resolution on HRF dynamics are also evaluated, we show that the use of small voxels (without spatial averaging) sampling parenchymal signals may enable faster observed hemodynamics.

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