1Rudolf Magnus Institute, University Medical Center Utrecht, Utrecht, Netherlands; 2Radiology, University Medical Center Utrecht, Utrecht, Netherlands; 3Stanford University, Stanford, CA, United States
An often reported mismatch between expected and measured BOLD responses with increasing stimulus rates has led to the notion that neurovascular coupling is non-linear. We assess the neurovascular coupling of the sensorimotor cortex with a motor task by combining presurgical 7T BOLD fMRI and high density intracranial electrocorticography (ECoG) grids post-implant in the same subjects. With increasing movement rate the amplitude of both the BOLD and the ECoG broadband high frequency gamma response declined. The latter explained almost 80% of the apparent BOLD nonlinearity, indicating that in human sensorimotor cortex the BOLD response is tightly linked to neuronal activity.