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Abstract #0716

Cortical Depth & Functional Duty Cycle Dependence of the Initial Dip & Post-Stimulus Undershoot in Humans: A 7 Tesla BOLD Investigation.

Manus Donahue1, 2, Jeroen Siero, 23, Hans Hoogduin2, Natalia Petridou2, Peter Luijten2, Jeroen Hendrikse2

1Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States; 2Radiology, University Medical Center Utrecht, Utrecht, Netherlands; 3Rudolf Magnus Institute, University Medical Center Utrecht, Utrecht, Netherlands

The overall goal of this study was to investigate negative elements of the blood oxygenation level-dependent (BOLD) hemodynamic response function as a function of cortical depth and stimulus duration by performing high spatial (1.35 m in-plane) and temporal (TR=600 ms) BOLD fMRI in humans at 7 Tesla. Findings indicate that the initial dip is dependent on both cortical depth and stimulus duty cycle, with the largest dip present in peripheral cortical regions and in the first block of event-related paradigms. The post-stimulus undershoot was found to be largest in deeper cortical regions where capillary density is highest.