Tight Neurovascular Coupling in Human Sensorimotor Cortex: A Combined ECoG and 7T BOLD fMRI Experiment

Jeroen Cornelis Willem Siero¹, ², Dora Hermes¹, ³, Hans Hoogduin², Peter R. Luijten², Natalia Petridou², Nick F. Ramsey¹

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.