CBF-CMRO2 Coupling in the Default Mode Network

Pan Lin¹, Jorge Jovicich¹, Simon Robinson¹

The Default Mode is a network of brain regions which show reduced blood flow (CBF) and BOLD signal in the task state relative to baseline, independent of the nature of the task. There has been controversy over the origin of these signal fluctuations, which overlap to some extent with regions affected by respiration rate variation. We show for the first time that the coupling ratio between cerebral blood flow and cerebral metabolic rate of oxygen consumption is the same in task-independent deactivation as in activation, and thereby consistent with a neuronal basis for deactivation of the Default Mode.