Investigation of human brain hemodynamics by simultaneous near-infrared spectroscopy and functional magnetic resonance imaging

The aim of this study was to compare functional cerebral hemodynamic signal s obtained simultaneously by near infrared spectroscopy (NIRS) and by funct ional magnetic resonance imaging (fMRI). The contribution of superficial la yers (skin and skull) to the NIRS signal was also assessed. Both methods we re used to generate functional maps of the motor cortex area during a perio dic sequence of stimulation by finger motion and rest. In all subjects we f ound a good collocation of the brain activity centers revealed by both meth ods. We also found a high temporal correlation between the BOLD signal (fMR I) and the deoxy-hemoglobin concentration (NIRS) in the subjects who exhibi ted low fluctuations in superficial head tissues. (C) 2001 American Associa tion of Physicists in Medicine.