ADVANCED OPTICAL IMAGE PROBE FOR NEUROPHYSIOLOGY

最近的一些研究表明，认知过程依赖于扩展神经网络活动的空间和时间模式。光学成像技术可以在微观水平上提供有关参与这些过程的细胞的个体和集体行为的信息。我们建议开发一种先进的图像探针和数字采集系统，设计用于高性能的功能神经成像，利用本征光散射信号。该项目的第一个目标是改进图像探针的设计，使其对光散射的小而快速的变化具有高灵敏度。两种方法的反射模式照明将探讨荧光和偏振光的测量。该系统将包括一个电子可调滤波器，以特定波长照亮组织，用于光谱测量，以及一个强化检测器，用于动态荧光测量。第二个目标是对数据采集系统的硬件和软件进行改进。应用程序性能要求和集成多种数据模式的需要要求我们开发自定义数据采集硬件；该系统将控制CCD相机电路，每秒捕获、处理和存档2000帧，并发256通道的电生理数据。我们将把这些硬件集成到便宜的多处理器中。奔腾计算机系统，设计用于在多个处理器之间分配任务。该项目的第三个目标是应用该设备来研究与神经激活相关的光散射变化的性质和起源。我们在海马和髓质的初步研究已经证明了几种与神经激活相关的不同的光学变化，包括与神经肿胀和电传递同时发生的快速光散射变化，以及与血液动力学耦合代谢需求相关的较慢的光吸收变化。我们将检查光信号的光谱性质，表征我们已经确定的至少四个组件的时间，并采用物理和生理操作来识别和表征潜在的机制。

A number of recent studies suggest that cognitive processes rely on spatial and temporal patterns of activity in extended neural networks. Optical imaging techniques can provide information on a microscopic level about the individual and collective behavior of cells involved in these processes. We propose to develop an advanced image probe and digital acquisition system designed for high performance functional neural imaging using intrinsic light scattering signals. The first goal of the project is to improve the image probe design for high sensitivity to small and rapid changes in light scattering. Two methods of reflectance mode illumination will be explored for fluorescence and polarized light measurements. The system will incorporate an electronically tunable filter to illuminate tissue with specific wavelengths for spectroscopic measurements, and an intensified detector for dynamic fluorescence measurements. The second goal is to implement hardware and software improvements to the data acquisition system. Application performance requirements and the need to integrate of a number of data modalities require that we develop custom data acquisition hardware; the proposed system will control CCD camera circuitry, and capture, process and archive 2000 frames per second, with 256 channels of concurrent electrophysiological data. We will integrate this hardware into inexpensive, multiple processor. Pentium computer systems, designed for distributing tasks across multiple processors. The third goal for the project is to apply the device to investigate the nature and origin of light scattering changes associated with neural activation. Our preliminary studies in the hippocampus and medulla have demonstrated several different optical changes associated with neural activation, including fast light scattering changes concurrent with neural swelling and electrical transmission, and slower changes in light absorbance associated with hemodynamic coupling to metabolic demand. We will examine the spectral nature of the optical signals, characterize the timing of at least four components that we have identified, and employ physical and physiological manipulations to identify and characterize underlying mechanisms.