Vascular imprints of neuronal activity: Relationships between the dynamics of cortical blood flow, oxygenation, and volume changes following sensory stimulation

• DOI: 10.1073/pnas.94.26.14826
• Publication Date: 2002-07-26T14:43:20Z
• Authors: Dov Malonek; Ulrich Dirnagl; Ute Lindauer; Katsuya Yamada; Iwao Kanno; Amiram Grinvald
• Keywords: Deoxygenated Hemoglobin; Premovement neuronal activity; Functional Imaging; Sensory stimulation therapy; Haemodynamic response

Modern functional neuroimaging methods, such as positron-emission tomography (PET), optical imaging of intrinsic signals, and MRI (fMRI) utilize activity-dependent hemodynamic changes to obtain indirect maps the evoked electrical activity in brain. Whereas PET flow-sensitive map cerebral blood flow (CBF) changes, oxygenation level-dependent areas with concentration deoxygenated hemoglobin (HbR). However, relationship between CBF HbR during activation has never been tested experimentally. Therefore, we investigated this by using spectroscopy laser-Doppler flowmetry techniques, simultaneously, visual cortex anesthetized cats sensory stimulation. We found that earliest microcirculatory change was indeed an increase HbR, whereas lagged more than a second after HbR. The increased accompanied simultaneous total (Hbt), presumably reflecting early volume increase. Hbt 1 2 sec throughout response. These results support notion active neurovascular regulation capillary bed existence delayed, passive process filling.