A study on the perception mechanisms of the retina with a computational and a physiological approaches.

本项目的目的是从生理和计算的角度阐明视网膜神经网络的功能。本项目取得了以下成果。1).提出了一个描述视网膜外层神经元回路的线性模拟网络模型。2)利用该模型，我们用标准正则化理论描述了电路的空间滤波特性，在该理论中，早期的视觉问题归因于最小化一个代价函数。3).设计了一套光刺激系统，用于测量无长突细胞的响应特性。细胞内记录来自无长突细胞。本文研究了无长突细胞的感受野特性与形态之间的关系。4)采用Fura-2比值测定法测定细胞内游离钙离子浓度，探讨钙离子的调控机制。5)钙内流有电压门控钙通道和谷氨酸门控钙通道两条途径。6)、Na~(++)-Ca~(2+)-t；~(2+)&gt；~(2+)交换和Ca~(2+)&t；~(2+)-ATP泵可使细胞内的Ca~(2+)~(2+)~(gt；)排出。现在进行了一项计算研究来阐明这一点。

The purpose of this project was to elucidate the function of retinal neuronal network from the physiological and computational point of views. The following results were obtained in this project. 1).A linear analog network model was proposed to describe the neuronal circuit of the outer retina. 2).Using the model, we characterized the spatial filtering properties of the circuit in terms of the standard regularization theory, in which the early vision problems are attributed to minimization of a cost function. 3).A optical stimulator system was designed to measure the response properties of amacrine cells. The intracellular recordings were obtained from amacrine cells. A relation between the receptive field properties and the morphology of amacrine cells has been studied. 4).The intracellular concentration of Ca^<2+> was measured using fura-2 ratiometric method in isolated horizontal cells to study the Ca^<2+> regulation mechanism. 5).Two pathways of Ca^<2+> influx, i.e. the voltage-gated Ca^<2+> channels as well as the glutamate-gated channels were found. 6).The Na^+ -Ca^<2+> exchange and Ca^<2+> -ATP pump were found to extrude the intracellular Ca^<2+>.7).The results obtained in 5 and 6 suggested that the Ca^<2+> extrusion systems are also play important roles in shaping the light-evoked response in the horizontal cell. A computational study is now undertaken to elucidate this point.