Construction and analyzing of functional map in cerebral cortex using a newly developed dual wavelength measurement system for optically monitoring membrane potential from multiple site

我们研制了一套用于检测心房等收缩准备体1020位点膜电位的光学记录系统。在用电压敏感染料染色的制剂的光学记录中，强度变化反映了膜电位依赖性吸收变化和源自制剂运动的膜电位无关性光散射变化。我们可以利用波长对入射光的依赖性来分离这些信号。在这个系统中，我们使用红色和绿色超高亮度发光二极管作为光源，我们可以做几乎同时记录在两个不同的波长。本研究旨在将这种光学记录系统应用于大脑皮层。双波长记录在抑制心跳或呼吸引起的伪影方面似乎有很大的优势。为了检测大脑皮层中的光信号，我们必须将吸收检测系统改造成荧光测量系统。超高亮度发光二极管被放置在物镜透镜周围，并且放置彩色玻璃滤光片以切断绿色光。此外，我们必须新开发一个光学平台，用于将光学检测器设置到大脑皮层上的期望部分。作为第一步，我们已经光学记录了神经反应的左足垫电刺激在右侧大脑皮层附近的中央沟染色的电压敏感染料（RH 414）。交替地进行使用红光和绿色光作为激发光的记录。信号经计算机处理后，在右侧感觉皮层的有限区域内出现了光反应。该光学响应区域与使用相同大鼠通过电生理场测量记录的峰值电流密度的区域一致。

We developed an optical recording system for detecting the membrane potential from 1020-site in contracting preparation such as atrium. In the optical recording from the preparation stained with a voltage-sensitive dye, the intensity change reflects both membrane potential dependent absorption change and the membrane potential independent light scattering change derived from the movement of the preparation. We can separate these signals using the characteristic of wavelength dependency to incident light. In this system, we used red and green ultra high luminance light emitting diodes as the light source, and we can do practically simultaneous recording at two different wavelength. This study was designed to apply this optical recording system to a cerebral cortex. The dual wavelength recording seems to have a great advantages in suppressing the artifact derived from heartbeat or breathing. In order to detect an optical signal in the cerebral cortex, we have to rebuild the absorption detecting system to fluorescent measurement system. The ultra-high luminance light emitting diodes were placed surrounding the objective lens, and the colored glass filter was placed to cut the green light. Also, we have to newly developed an optical stage for setting the optical detector to a desired part on the cerebral cortex. As a first step, we have optically recorded neural response to left foot pad electrical stimulation in the right cerebral cortex near the central groove stained with voltage sensitive dye (RH 414). The record using a red light and green light, as an excitation light, were alternatively carried out. After the signal were processed by the computer, the optical response appeared in a limited region in the right sensory cortex. This optical response area was consistent with the area where the peak current density was recorded by an electrophysiological field measurement using the same rat.