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

我们开发了一种光学记录系统，用于检测心房等收缩准备中1020位点的膜电位。在用电压敏感染料染色的制备的光学记录中，强度变化反映了膜电位依赖的吸收变化和膜电位独立的光散射变化，这是由制备的运动引起的。我们可以利用波长依赖于入射光的特性来分离这些信号。在这个系统中，我们使用红色和绿色的超高亮度发光二极管作为光源，我们可以在两个不同的波长同时进行记录。本研究旨在将这种光学记录系统应用于大脑皮层。双波长记录在抑制由心跳或呼吸产生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为荧光测量系统。在物镜周围放置超高亮度发光二极管，并放置有色玻璃滤光片切断绿光。此外，我们还开发了一种光学平台，可以将光学探测器设置在大脑皮层的指定位置。作为第一步，我们光学记录了左脚垫电刺激对右脑皮层中央沟附近的神经反应，该中心沟被电压敏感染料染色（RH 414）。使用红光和绿光作为激励光，交替进行记录。信号经过计算机处理后，在右侧感觉皮层的有限区域出现了光响应。该光学响应区域与同一只大鼠电生理场测量记录的峰值电流密度区域一致。

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.