The functional role of intracellular calcium signaling in retinal amacrine cells, particularly with respect to computation of visual stimuli

视网膜是一个复杂的图像处理器，它从观察到的场景中过滤、提取和编码特征，并将这些信息转发到大脑的视觉区域。高空间分辨率和快速编码需要紧凑的视网膜电路并行处理。将计算能力集中在神经基质上的一种有效方法是树突处理——神经元在其树突中局部处理输入的能力。无突细胞（最大的一类视网膜中间神经元）利用树突处理：它们中的大多数是无轴突的，使用它们的神经突来接收和提供突触的输入和输出。一个突出的例子是星爆无突细胞，它是检测图像运动方向所必需的。它的树突分支在很大程度上是独立活动的，并产生运动方向相关的信号。潜在的树突自主机制依赖于电压门控通道（可能是钙通道），此外还可能涉及细胞内Ca2+储存。利用双光子Ca2+成像、药理学和病毒基因转移，该项目的主要目标是确定细胞内Ca2+信号在星囊腺树突时空输入模式检测中的功能作用。

The retina is a sophisticated image processor that filters, extracts and encodes features from the observed scene and forwards this information to the visual areas of the brain. High spatial resolution and fast encoding necessitates parallel processing by compact retinal circuitries. An effective way to concentrate computing power in neural substrate is dendritic processing ¿ the ability of a neuron to process inputs locally in its dendrites. Amacrine cells ¿ the largest class of retinal interneurons ¿ make use of dendritic processing: most of them are axon-less, using their neurites for receiving and providing synaptic input and output. A prominent example is the starburst amacrine cell, which is necessary for detecting the direction of image motion. Its dendritic branches act largely independently and generate motion direction-dependent signals. The underlying dendrite-autonomous mechanism relies on voltage-gated channels ¿ likely on calcium channels ¿ and may, in addition, involve intracellular Ca2+ stores. Using two-photon Ca2+ imaging, pharmacology and viral gene-transfer the primary goal of this project is to determine the functional role of intracellular Ca2+ signaling for the detection of spatio-temporal input patterns in starburstamacrine dendrites.