Nemoto M, Nomura Y, Sato C, Tamura M, Houkin K, Koyanagi I, Abe H
Department of Neurosurgery, Hokkaido University School of Medicine, Sapporo, Japan.
J Cereb Blood Flow Metab. 1999 Mar;19(3):246-59. doi: 10.1097/00004647-199903000-00002.
The origins of reflected light changes associated with neuronal activity (optical signals) were investigated in rat somatosensory cortex with optical imaging, microspectrophotometry, and laser-Doppler flowmetry, and dynamic changes in local hemoglobin concentration and oxygenation were focused on. Functional activation was carried out by 2-second, 5-Hz electrical stimulation of the hind limb under chloralose anesthesia. These measurements were performed at the contralateral parietal cortex through a thinned skull. Regional cortical blood flow (rCBF) started to rise 1.5 seconds after the stimulus onset, peaked at 3.5 seconds (26.7% +/- 9.7% increase over baseline), and returned to near baseline by 10 seconds. Optical signal responses at 577, 586, and 805 nm showed a monophasic increase in absorbance coincident with the increase in rCBF; however, the signal responses at 605 and 760 nm were biphasic (an early increase and late decrease in absorbance) and microanatomically heterogeneous. The spectral changes of absorbance indicated that the concentrations of both total hemoglobin and oxyhemoglobin increased together with rCBF; deoxyhemoglobin, increased slightly but distinctly (P = 0.016 at 1.0 seconds, P = 0.00038 at 1.5 seconds) just before rCBF increases, then decreased. The authors conclude that activity-related optical signals are greatly associated with a moment-to-moment adjustment of rCBF and metabolism to neuronal activity.
利用光学成像、显微分光光度测定法和激光多普勒血流测定法，在大鼠体感皮层研究了与神经元活动相关的反射光变化（光学信号）的起源，并聚焦于局部血红蛋白浓度和氧合的动态变化。在水合氯醛麻醉下，通过对后肢进行2秒、5赫兹的电刺激来实现功能激活。这些测量是通过变薄的颅骨在对侧顶叶皮层进行的。刺激开始后1.5秒，局部皮层血流量（rCBF）开始上升，在3.5秒时达到峰值（比基线增加26.7%±9.7%），并在10秒时恢复到接近基线水平。在577、586和805纳米处的光学信号响应显示吸光度呈单相增加，与rCBF的增加一致；然而，在605和760纳米处的信号响应是双相的（吸光度早期增加，后期减少），并且在微观解剖学上是异质的。吸光度的光谱变化表明，总血红蛋白和氧合血红蛋白的浓度都随rCBF的增加而增加；脱氧血红蛋白在rCBF增加之前略有但明显增加（1.0秒时P = 0.016，1.5秒时P = 0.00038），然后下降。作者得出结论，与活动相关的光学信号与rCBF和代谢对神经元活动的瞬间调节密切相关。
