Reswanul Khan1, Sucharit Katyal2, Clint Greene2, Evan Luther3, David Ress2
1Neurobiology, Physics, Imaging Research Center, Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, United States; 2Neurobiology, Psychology, Imaging Research Center, Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, United States; 3Neurobiology, Biomedical Engineering, Imaging Research Center, Center for Perceptual Systems, The University of Texas at Austin, Austin, TX, United States
At conventional resolutions, BOLD fMRI samples responses from various tissues in cerebral cortex: white matter, gray matter, and extra-pial. Here, we utilize high-resolution fMRI (0.9-mm voxels) to characterize the BOLD hemodynamic response function (HRF), as it varies with depth and tissue type in cortex. Surface-based analysis methods create a normalized depth coordinate that permits characterization throughout the variable thickness of gray matter. The HRF peak response occurs faster in deep gray matter, but is stronger and noisier in more superficial tissue. No significant initial dip is present in the gray matter, but is clearly evident in extra-pial tissues.
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