The BOLD fMRI Post-Stimulation Undershoot in Human Primary Motor Cortex is Not Caused by Elevated CBV

Peter Dechent¹, Gunther Helms¹, Dietmar Merboldt², Jens Frahm²

The post-stimulation undershoot in BOLD fMRI may be due to a delayed recovery of elevated CBV or CMRO₂. To exclude the possibility that contradicting results in humans and animals originate from studies of different cortical systems, we performed contrast-enhanced T1-weighted fMRI in humans to evaluate CBV during a motor task. The results confirm a CBV increase during finger movements and reveal CBV baseline levels in the post-stimulation phase. This finding is in line with previous results from human visual cortex. It renders discrepant findings from human and animal studies unlikely to be caused by the specific cortical system investigated.