Biophysical limitations to signal transmission in the mammalian retina

对于捕食者和猎物以及许多哺乳动物来说，夜间观看都有相当大的进化优势， 包括人类在内，都有极好的夜视能力。人类可以感觉到微弱的闪光产生单一的 约1/100棒的光子吸收，这表明由单个光子产生的信号是 通过视网膜可靠地传输到大脑。我们已经详细了解了棒子是如何 光感受器将单个光子编码为电信号，但人们对这些微小的光子如何编码知之甚少 信号通过视网膜传输。这项研究的总体目标是获得一个定量的 了解通过视网膜的单光子突触传递。我们将使用鼠标作为模型 系统，因为他们有发达的夜视，并成为一个很好的模型系统 哺乳动物的杆状视觉。单光子信号的记录将从链中的每个神经元进行 连接杆状细胞和神经节细胞的神经元。响应暗淡而产生的电压和电流信号 将对闪光进行分析。具体目标包括：1)确定棒的增益控制机制 突触，2)确定控制杆中会聚噪声的非线性的性质 细胞，3)分解神经节细胞中的单光子信号。我们对正常视网膜的认识进展 功能将提高我们对视网膜疾病引起的功能障碍的理解。我们的结果将 与导致夜盲的疾病有特别的相关性。

Seeing at night has considerable evolutionary advantages both for predators and prey, and many mammals, including humans, have excellent night vision. Humans can perceive dim light flashes that produce single photon absorption in about 1 in 100 rods, which indicates that signals generated by single photons are reliably transmitted through the retina to the brain. We have a detailed understanding about how the rod photoreceptors encode single photons as electrical signals, but relatively little is known about how these tiny signals are transmitted through the retina. The general goal of this research is to gain a quantitative understanding of single photon synaptic transmission through the retina. We will use the mouse as a model system, because they have a well-developed night vision, and make an excellent model system for mammalian rod vision. Recordings of single photon signals will be made from each neuron in the chain of neurons connecting the rods to the ganglion cells. Voltage and current signals generated in response to dim light flashes will be analyzed. Specific aims include 1) determining the mechanisms of gain control at the rod synapse, 2) determining the nature of the non-linearity that controls convergent noise in the rod All amacrine cells, 3) resolving the single photon signal in ganglion cells. Advances in our understanding of normal retinal function will improve our understanding of the dysfunctions that result from retinal disease. Our resultswill have particular relevance to diseases that cause night blindness.