Krüger G, Kleinschmidt A, Frahm J
Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie Am Fassberg 11, Göttingen, Germany.
Magn Reson Med. 1996 Jun;35(6):797-800. doi: 10.1002/mrm.1910350602.
Changes in cerebral blood oxygenation and flow during prolonged activation of human visual cortex (6-min video projection) were monitored using high-resolution T2*- and T1-weighted gradient-echo MRI in identical sessions. Oxygenation-sensitive recordings displayed an initial signal increase (oxygenation "overshoot"), a subsequent signal decrease extending over 4-5 min (relative deoxygenation), and a signal drop after the end of stimulation that mirrored the initial response (oxygenation "undershoot"). Flow-sensitive MRI demonstrated that the inflow effect remained elevated during the entire period of stimulation. The observation of gradually decreasing cerebral blood oxygenation, despite persisting elevation of blood flow, may be understood to be an accumulation of deoxyhemoglobin due to the progressive up-regulation of oxidative phosphorylation. The present findings support a concept in which transitions between functional states lead to an uncoupling of perfusion (oxygen delivery) from oxidative metabolism (oxygen consumption) whereas steady-state activity achieves their recoupling.
在相同的实验环节中，使用高分辨率T2*加权和T1加权梯度回波磁共振成像监测了人类视觉皮层长时间激活（6分钟视频投影）期间脑血氧合和血流的变化。氧合敏感记录显示，最初信号增强（氧合“过冲”），随后信号减弱持续4 - 5分钟（相对脱氧），刺激结束后信号下降，与初始反应相反（氧合“欠冲”）。血流敏感磁共振成像表明，在整个刺激期间，流入效应持续升高。尽管血流持续升高，但脑血氧合逐渐降低的现象，可能是由于氧化磷酸化的逐步上调导致脱氧血红蛋白积累所致。本研究结果支持这样一种概念，即功能状态之间的转变导致灌注（氧输送）与氧化代谢（氧消耗）解偶联，而稳态活动则实现它们的重新偶联。
