Development of visualization system for neural activity and microcirculation of cerebral cortex.

大脑微循环的分析是重要的，因为大脑皮层的高级功能完全依赖于血液流动。本研究的目的是利用针探头CCD活体显微镜，建立在体观察大脑皮层微循环和神经活动的系统。在第一年，我们专注于微动脉和微静脉的可视化，并开发了一个新的系统，并检查系统的可行性。该系统由带中继透镜的探针、三片式CCD和高分辨率显示器组成。该系统的时间和空间分辨率分别为33ms和2 μ m，无图像畸变，在麻醉犬上能清晰地观察软脑膜微动脉、微静脉和红细胞的运动。此外，我们还可以通过针探针的插入观察到大脑皮层内的微血管。在接下来的一年里，我们研究了脑血流的调节机制。吸入10%CO_2、颈动脉内注射硝酸甘油或腺苷可显著增加颈动脉血流量。与此相应，软膜微动脉也显著扩张。相对较小的动脉（直径<75 μ m）扩张较多，而相对较大的动脉（直径× 75 μ m）扩张不明显。结论：局部脑血流主要由较小的微动脉（<75 μ m）调节。这一机制可能有利于局部脑血流的精细调节。

Analysis of cerebral microcirculation is of importance, as higher function of cerebral cortex is completely dependent on blood flow. The purpose of this study was to develop in vivo visualization system for microcirculation and neural activity of cerebral cortex by using needle probe CCD intravital microscope. During the first year we focused on visualization of arteriole and venule and developed a new system, and checked feasibility of the system. This system is composed of a needle-probe with relay lens, three-plate CCD and high difinition monitor. Time and space resolution of this system is 33ms and 2mum, respectively, and distortion of image was not found. In anesthetized dogs, we could clearly observe pial arteriole and venule and movement of red blood cell. Furthermore, we could observe microvessels within cortex by insertion of the needle-probe.In the next year, we investigated the mechanism (s) of regulation of cerebral blood flow. Inhalation of 10% CO_2, intracarotid injection of nitrol or adenosine remarkably increased carotid blood flow. In accordance with this increase, pial arteriole remarkably dilated. Relatively smaller arteriole (diameter<75mum) dilated much, but relatively larger arteriole (diameter*75mum) did not dilate significantly. In conclusion local cerebral blood flow is regulated mainly by relatevely smaller arteriole (<75mum). This mechamism may be beneficial for fine regulation of local cerebral blood flow.