Comprehensive quantification of cone dynamics

项目摘要 视觉形成了我们日常生活的一个重要部分，而这个感觉过程始于 由一种称为视锥细胞的特殊感光器捕获光，这种感光器非常适应日光 条件下，高敏锐度的视觉，和颜色感知。锥的基本响应性质 在分离的细胞或视网膜组织中进行的研究中已经大量描述了光感受器。 令人惊讶的是，许多这些响应特性，如时间动态和强度， 灵敏度范围，在文献中仍有争议。此外，其中一些与 数据采集在体内和人类的视觉表现时，测量心理。的 这项赠款的主要目的是产生一个更全面的表征锥 视锥细胞为主的动物，包括灵长类动物的光感受器。这将通过联合 在完整的视网膜外植体中进行的实验与体内记录平行， 现在可以用自适应光学微刺激瞄准单个锥体。相似刺激 范例将用于每种实验方法中以测量强度响应 函数，达到峰值时间的快速性，饱和刺激后的衰减动力学，以及 适应率响应于不断变化的背景光水平。这些数据将用于 建立了一个完整的基于视锥光转导的响应特性理论模型 这将是非常有用的视觉科学家，并可能划定的限制和边界， 视网膜上的体内与体外实验。另一个目的是详细说明一种新的形式 通过脉冲红外双光子激发的视锥激活可以用于改善空间 刺激锥体。双光子实验最好与传统的单光子实验交叉进行。 光子刺激，以检查如何2-光子激发机制不同于1- 光子吸收，并且还确定可以产生多少内源性荧光 这样的刺激。因为双光子吸收可以用来测量视锥细胞的健康 周期，了解红外刺激的基本响应特性将是 视锥细胞功能和疾病的未来研究。

Project Summary Vision forms a prominent part of our daily lives, and this sensory process begins with the capture of light by a particular class of photoreceptor called cones, a class well adapted to daylight conditions, to high acuity vision, and to color perception. The basic response properties of cone photoreceptors have been largely described in studies conducted in isolated cells or retinal tissue. Surprisingly, many of these response properties, such as temporal dynamics and intensity sensitivity range, remain controversial in the literature. Moreover, some of them conflict with data acquired in vivo and with human visual performance when measured psychophysically. The primary aims of this grant are to generate a more comprehensive characterization of cone photoreceptors in cone-dominated animals, including primates. This will be achieved by conjoint experiments conducted in intact retinal explants in parallel with in vivo recordings where it is now possible to target single cones with adaptive optics microstimulation. Similar stimulation paradigms will be employed in each experimental approach to the measure intensity response functions, the rapidity of time-to-peak, the decay kinetics following saturating stimuli, and the adaptation rate in response to changing background light levels. These data will be used to develop a complete theoretical model of response properties based on cone phototransduction which will be of great use to vision scientists and may delineate the limits and boundaries of in vivo vs. in vitro experiments on the retina. An additional aim will be to detail how a novel form of cone activation—via pulsed infrared 2-photon excitation—may be used for improved spatial stimulation of cones. The 2-photon experiments are best done interleaved with traditional 1- photon stimulation in order to examine how the 2-photon excitation mechanism differs from 1- photon absorption, and also to determine how much endogenous fluorescence may be generated by such stimuli. As 2-photon absorption may be used to measure the health of the cone visual cycle, understanding the basic response properties of infrared stimulation will be foundational for future studies of cone function and disease.