Villringer A, Chance B
Neurologische Klinik, Charité, Humboldt-Universität Berlin, Germany.
Trends Neurosci. 1997 Oct;20(10):435-42. doi: 10.1016/s0166-2236(97)01132-6.
Brain activity is associated with changes in optical properties of brain tissue. Optical measurements during brain activation can assess haemoglobin oxygenation, cytochrome-c-oxidase redox state, and two types of changes in light scattering reflecting either membrane potential (fast signal) or cell swelling (slow signal), respectively. In previous studies of exposed brain tissue, optical imaging of brain activity has been achieved at high temporal and microscopical spatial resolution. Now, using near-infrared light that can penetrate biological tissue reasonably well, it has become possible to assess brain activity in human subjects through the intact skull non-invasively. After early studies employing single-site near-infrared spectroscopy, first near-infrared imaging devices are being applied successfully for low-resolution functional brain imaging. Advantages of the optical methods include biochemical specificity, a temporal resolution in the millisecond range, the potential of measuring intracellular and intravascular events simultaneously and the portability of the devices enabling bedside examinations.
大脑活动与脑组织光学特性的变化相关。大脑激活过程中的光学测量可以评估血红蛋白氧合、细胞色素c氧化酶的氧化还原状态，以及分别反映膜电位（快速信号）或细胞肿胀（慢速信号）的两种光散射变化。在先前对暴露脑组织的研究中，已在高时间分辨率和微观空间分辨率下实现了大脑活动的光学成像。现在，利用能够较好穿透生物组织的近红外光，已经可以通过完整颅骨对人类受试者进行非侵入性的大脑活动评估。在早期采用单通道近红外光谱学的研究之后，首批近红外成像设备已成功应用于低分辨率功能性脑成像。光学方法的优点包括生化特异性、毫秒级的时间分辨率、同时测量细胞内和血管内事件的潜力，以及设备的便携性，可实现床边检查。
