title: Changes of cerebral blood flow, oxygenation, and oxidative metabolism during graded motor activation.
abstract: In the present studies fMRI and a hypercapnic calibration procedure were used to monitor simultaneous changes in cerebral blood flow (CBF), cerebral blood oxygenation, and cerebral metabolic rate of oxygen (CMRO(2)) during activation in the sensorimotor cortex. In the first set of experiments seven volunteers performed bilateral, self-paced finger tapping and in the second set of experiments six volunteers performed bilateral finger tapping with six different frequencies (0.5-3 Hz). During the latter task relative CBF and BOLD signal intensity changes varied linearly as a function of stimulus frequency. In good agreement with recent PET and fMRI data increases in CMRO(2) were smaller than the corresponding changes in CBF during self-paced finger tapping and at all levels of graded motor activation. At a single level of activation and during graded activation there was a positive linear relationship between CBF and CMRO(2) with ratios of approximately 3:1. Comparable proportionality constants have been found in the visual cortex and primary sensory cortex, indicating similarities between the relationship of CBF and CMRO(2) in various cortical regions.
authors.affiliation: Department of Radiology, Stanford University School of Medicine, Stanford, California 94305-5488, USA.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kastrup
authors.forename: Gunnar
authors.initials: G
authors.lastname: Krüger
authors.forename: Tobias
authors.initials: T
authors.lastname: Neumann-Haefelin
authors.forename: Gary H
authors.initials: GH
authors.lastname: Glover
authors.forename: Michael E
authors.initials: ME
authors.lastname: Moseley
mesh_terms: D000328:Adult; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000098:blood supply / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D014793:Visual Cortex / Q000098:blood supply / Q000502:physiology*