Optical recording system for monitoring neural activity in deep region of the brain.

使用电压敏感染料监测细胞跨膜电压活性的光学方法比传统的电生理技术有许多优点。然而，当应用于中枢神经系统时，记录仅限于大脑表面。为了克服这一困难，我们开发了一种新的系统来测量中枢神经系统深部区域的神经活动，该系统使用单个光纤，用于激发和检测先前加载的电压敏感染料的荧光。该系统由激发光源、光纤、荧光检测器和记录单元组成。将卤钨灯发出的光送入干涉滤光片，所得到的激发光通过光纤引导至所述制备物。发出的荧光由连接到光电二极管的同一根光纤收集，光电二极管的输出输入记录单元。数据采集的时间由记录仪调节。利用所使用的电压敏感染料，可以选择激发和发射滤光片，以获得最佳的荧光信号。这个新系统首先应用于迷走神经束来评估该装置的灵敏度。用膜不渗透电压敏感苯乙烯染料（RH795）染色。该光学信号是通过微吸电极对迷走神经施加一个短暂的方电流脉冲来激发的。在诱发光信号中，动作电位成分具有较好的信噪比。光信号的数量级为10^<-3>，呈分数阶变化。由于该光学记录系统具有良好的信噪比和时间分辨率，因此可以很好地用于分析中枢神经系统深部神经活动。

Optical methods for monitoring cellular transmembrane voltage activity, using voltage-sensitive dyes, offer many advantages over conventional electrophysiological techniques. However, when applying to the central nervous system, the recording has been limited to the surface of the brain. To overcome this difficulty, we developed a new system to measure the neural activity in the deep region of the central nervous system with a single fiber optics, used for both excitation and detection of the fluorescence of the voltage-sensitive dye that is previously loaded. This system consists of an excitation light source, a fiber optics, a fluorescence detector and a recording unit. The light emitted from a tungsten-halogen lamp is fed into an interference filter, and the excitation light obtained is guided to the preparation through the fiber optics. The emitted fluorescence is collected by the same fiber connected to a photodiode whose output is fed into the recording unit. The timing of the data acquisition is regulated by the recorder. The excitation and emission filters can be chosen so as to give the best fluorescence signal with the used voltage-sensitive dye.This new system has first been applied to a vagus nerve bundle to evaluate the sensitivity of the device. The preparation was stained with a membrane-impermeable voltage-sensitive styryl dye (RH795). The optical signals were evoked by a brief square-current pulse applied with a micro-suction electrode to the vagus nerve. In the evoked optical signals, action potential component was detedted with a relatively good S/N ratio. The optical signal was on the order of 10^<-3> in a fractional change. Because of the good S/N ratio as well as good temporal resolution, this new optical recording system was confirmed to be well suitable for analyzing the neural activity in the deep region of the central nervous system.