Spatially dissociated flow-metabolism coupling in brain activation

The relationships among cerebral blood flow (CBF), oxygen consumption (CMRO2) and glucose use (CMRg]c) constitute the basis of functional brain-imaging. Here we report spatially dissociated changes of CMRO2 and CBF during motor activity that lead us to propose a revision of conventional CBF-CMRO2 coupling models. In the left primary and supplementary motor cortices, CBF and CMRO2 rose significantly during finger-thumb tapping. However, in the right putamen CBF did not rise, despite a significant increase in CMRO2. We explain these observations by invoking a central command mechanism that regulates CBF in the putamen in anticipation of movement. By this mechanism, CBF rose in the putamen before the measurements of CBF and CMRO2 while CMRO2 rose when actual motion commenced. (C) 2003 Elsevier Inc. All rights reserved.