Fig. 5. Blood oxygenation level-dependent (BOLD) signal intensity time courses (averaged across all subjects) in the frontal, temporal, parietal, and occipital cortices and in the white matter and the cerebellum during hyperventilation. Esmolol at the dose studied caused no change in cerebral vasoreactivity as indicated by the identical BOLD signal intensity time courses in all of the investigated brain regions during normoventilation and hyperventilation.