A Systematic Analysis of the Impact of Hemodynamic, Metabolic and Vascular Factors on the BOLD Signal

In fMRI studies changes in BOLD signal intensities during task activation are related to multiple physiological parameters such as cerebral blood flow (CBF), cerebral blood volume (CBV), and oxidative metabolism (CMRO2), as well as to the regional microvascular anatomy. The aim of the present studies was to systematically analyze the contribution of these factors to BOLD signal changes during neuronal activation. Assuming similarities between the mechanisms responsible for the coupling of CBF to neuronal activation and the increase of CBF during hypercapnia, a global hypercapnic challenge was used to indirectly…