Vascular imprints of neuronal activity: Relationships between the dynamics of cortical blood flow, oxygenation, and volume changes following sensory stimulation
Vascular imprints of neuronal activity: Relationships between the dynamics of cortical blood flow, oxygenation, and volume changes following sensory stimulation
复制标题
DOI：
10.1073/pnas.94.26.14826
复制
发表时间：
1997-12-23
影响因子：
11.1
通讯作者：
Grinvald, A
中科院分区：
文献类型：
--
作者：
Malonek, D;Dirnagl, U;Grinvald, A
现代功能性神经成像方法，例如正电子发射断层扫描（PET）、内在信号的光学成像和功能性MRI（fMRI），利用活动依赖性血流动力学变化来获得脑中诱发电活动的间接图。而PET和血流敏感MRI图脑血流量（CBF）的变化，光学成像和血氧水平依赖的MRI图区域与脱氧血红蛋白（HbR）浓度的变化，然而，CBF和HbR之间的关系在功能激活过程中从未被实验验证过，因此，我们同时使用成像光谱和激光多普勒血流仪技术来研究这种关系，在感觉刺激过程中，麻醉猫视皮层的微循环变化最早确实是HbR的增加，而CBF的增加滞后于HbR的增加一秒以上。HbR的增加伴随着总血红蛋白浓度（Hbt）的同时增加，这可能反映了早期血容量的增加。我们发现，CBF的变化滞后于Hbt的变化1至2秒的整个反应，这些结果支持的概念，主动神经血管调节血容量的毛细血管床和存在一个延迟的，被动的毛细血管充盈过程。
Modern functional neuroimaging methods, such as positron-emission tomography (PET), optical imaging of intrinsic signals, and functional MRI (fMRI) utilize activity dependent hemodynamic changes to obtain indirect maps of the evoked electrical activity in the brain. Whereas PET and flow-sensitive MRI map cerebral blood flow (CBF) changes, optical imaging and blood oxygenation level-dependent MRI map areas with changes in the concentration of deoxygenated hemoglobin (HbR), However, the relationship between CBF and HbR during functional activation has never been tested experimentally, Therefore, we investigated this relationship by using imaging spectroscopy and laser-Doppler flowmetry techniques, simultaneously, in the visual cortex of anesthetized cats during sensory stimulation, We found that the earliest microcirculatory change was indeed an increase in HbR, whereas the CBF increase lagged by more than a second after the increase in HbR, The increased HbR was accompanied by a simultaneous increase in total hemoglobin concentration (Hbt), presumably reflecting an early blood volume increase. We found that the CBF changes lagged after Hbt changes by 1 to 2 sec throughout the response, These results support the notion of active neurovascular regulation of blood volume in the capillary bed and the existence of a delayed, passive process of capillary filling.