蛙视网膜信息加工模式的数学模拟

A mathemetical simulation of the information processing in the frog retina

把蛙视网膜外网状层看作平面时间三维系统，其输入为视网膜照度，输出是由双极细胞传到下级系统的感受器电位．设想该系统的信息加工模式：感光细胞除直接向双极细胞输出一个神经信号外，还向水平细胞输出一个神经信号，该信号在水平细胞体内横向传播，形成一个圆形接受域，其强度随圆面积增大以指数式衰减，传输到双极细胞后形成抑制信号；输入双极细胞的两个信号都随时间以指数式衰减．根据信息加工模式建立数学模型，得到点脉冲照度产生的点脉冲响应．运用 Ｆｏｕｒｉｅｒ

The outer plexiform layer of the frog retina was taken as a three dimensional system, of which the input was illuminance on the frog retina, and the output was receptor potential transmitted to the lower level system by bipolar cells. The pattern of this system's information processing was supposed to be that besides transmitting one nerve signal directly to bipolar cells, photosensory cells would transmit another nerve signal to horizontal cells, which would be transmitted to all directions in the horizontal cells forming an accepting region of disk shape, then be transmitted to the bipolar cells becoming inhibitory signals, while the strength of which would go into exponential decay with the disk area increasing. The two signals would go into exponential decay with time when they are brought into the bipolar cells. In accordance with the pattern, a mathematical model was established, and a point impulse response of caused by illuminance of was acquired. According to the result of Fourier analysis, it was confirmed that the model corresponded with the feature detectors of the frog eye in spatial filtering.