A Depth-resolved Voltage Sensitive Dye Imaging System

描述（由申请人提供）：我们建议开发一种电压敏感染料（VSDs）和皮质血流动力学的深度分辨率光学成像系统，以便在体内（大鼠）研究三维（3D）神经血管耦合。神经元激活和相应的血流动力学反应之间的关系对于理解功能激活的机制至关重要，特别是与功能磁共振成像（fMRI）的解释相关。一旦引入皮层，vsd的荧光与膜电位成比例地改变，从而表明神经元活动的变化。我们已经开发了一种通过薄颅骨对大鼠皮层氧和脱氧血红蛋白变化进行三维光学成像的系统，称为层流光学断层扫描（LOT）。我们建议提前LOT。除了较慢的血流动力学吸收变化外，还可以同时对快速、小的VSD荧光变化进行3D成像。LOT系统类似于共聚焦显微镜，但它不是改变焦深，而是检测多次散射光，可用于以100-200微米分辨率重建深度为>2mm的结构图像。迄今为止，VSD成像使用的是皮质的2D相机图像，这些图像非常肤浅，无法提供深度分辨率。我们同时对vsd和血流动力学进行三维成像的动机有两个方面：1)我们假设，为了正确量化神经活动和血流动力学之间的关系，这两种测量必须在三维空间上共定位：二维荧光和吸收图像的深度灵敏度非常不同，因此它们的二维像素并不代表皮层中相同的三维位置。2)电生理学表明神经元活动具有层特异性。一种非侵入性的方法来研究神经元在皮层层之间移动和扩散时的三维动态，将为研究体内皮层功能活动提供一种全新的方法。我们建议开发荧光lot (PLOT)，然后使用接受体感刺激的大鼠进行初步系统测试。提高对神经元活动和功能磁共振成像信号之间的相关性的理解对人类大脑成像至关重要。异常病理对神经血管耦合的影响为治疗和预防提供了新的思路。新系统还可以应用于眼部、皮肤、内窥镜和肿瘤成像。

DESCRIPTION (provided by applicant): We propose to develop a system for depth-resolved optical imaging of both voltage sensitive dyes (VSDs) and cortical hemodynamics, to enable study of three-dimensional (3D) neurovascular coupling in-vivo (rats). The relationship between neuronal activation and the corresponding hemodynamic response is of fundamental importance for understanding the mechanisms of functional activation, and particularly relevant to interpretation of functional magnetic resonance imaging (fMRI). Once introduced into the cortex, VSDs change their fluorescence proportionally to membrane potential, thereby indicating changes in neuronal activity. We have already developed a system for 3D optical imaging of oxy and deoxy-hemoglobin changes in rat cortex through thinned skull, called Laminar Optical Tomography (LOT). We are proposing to advance LOT.s hardware and algorithms to allow concurrent 3D imaging of rapid, small VSD fluorescence changes in addition to slower hemodynamic absorption changes. The LOT system is similar to a confocal microscope, but rather than varying focal depth, it detects multiply scattered light, which can be used to reconstruct images of structures to depths of >2mm with 100-200 micron resolution. VSD imaging to date has utilized 2D camera images of the cortex, which are very superficially weighted and provide no depth-resolution. Our motivation to simultaneously image VSDs and hemodynamics in 3D is twofold: 1) We hypothesize that to properly quantify the relationship between neural activity and hemodynamics, the two measures must be spatially co-localized in 3D: The depth-sensitivities of 2D fluorescence and absorption images are very different, and so their 2D pixels do not represent the same 3D locations in the cortex. 2) Electrophysiology has demonstrated that neuronal activity is layer-specific. A non-invasive way to study the 3D dynamics of neuronal activation as it moves and spreads between cortical layers would provide a completely new way to study cortical functional activity in-vivo. We propose to develop Fluorescent-LOT (PLOT) and then perform preliminary system testing using rats undergoing somatosensory stimulus. Improved understanding of the correlation between neuronal activity and fMRI signals is of prime importance to human brain imaging. The effects of abnormal pathologies on neurovascular coupling could provide new insights for treatment and prevention. The new system could also find applications in ocular, dermal, endoscopic and tumor imaging.