Xiang He1, Dmitriy A. Yablonskiy1
Quantification of brain hemodynamic parameters during functional activation is essential for understanding biophysical mechanisms behind blood oxygenation level depend (BOLD) phenomenon. Models of BOLD signal are often derived based on a relationship established by PET studies between cerebral blood volume (CBV) and cerebral blood flow (CBF), ignoring that only portion of CBV - deoxyhemoglobin-containing blood volume (DBV) affects BOLD signal. In this study, we directly measure DBV during visual activation in human visual cortex area using qBOLD-fMRI technique. We demonstrate for the first time that DBV decreases during functional activation an effect opposite to well known increase in CBV.