Propagation of Backward Signal in the Neural Circuit of Retina

脊椎动物视网膜是神经组织的一部分，包含六种神经元和一种起源于大脑的离心纤维。进入视网膜的光信号被光感受器捕获。神经节细胞是输出神经元，将所有视觉信息从视网膜传递到大脑。除了上述信号流之外，最近的研究表明视网膜神经元容易受到经由离心纤维和网间细胞的中枢影响（Stell等人，1984 ; Umino等人，1991年）。该项目的目的是研究后向信号的传播，主要与感受野特性有关（参见Umino等人，1991年，在视网膜。主要结果和发现如下。(1)研制了一种由阴极射线管组成的新型光刺激器，用于检测视网膜神经元的感受野特性。(2)双极细胞通过间隙连接电偶联。双极电池的电耦合， ...更多信息 明了感受野中心，具有减少来自视锥的输入信号的分散的优点，并且允许减少双极细胞中的空间噪声。(3)将时变随机正方形光信号应用于视网膜，研究了视网膜感受野的时域和空域特性。光信号与水平细胞响应之间的互相关函数表明，水平细胞最初以其感受野中心对光作出响应，然后可以对光作出响应的区域被扩大到周围。(4)水平细胞的感受野特性在背景光照射后没有改变。然而，在长时间应用背景光后，感受野逐渐缩小并趋于平稳。因此，与明/暗适应有关的水平细胞感受野的收缩可以参与thUmino & Dowling（1991 a）的向后信号传播功能。Journal of Neuroscience 11，3034- 3046 Umino. Lee & Dowling（1991 b）.视觉神经科学7.451- 458 Stell等人，（1984）Proc Natl.Acad.Sci.USA.81：940-944 Less

The vertebrate retina is a portion of nervous tissue, containing six types of neurons and one type of centrifugal fibers originating in the brain. The light signal, entering the retina, is captured by the photoreceptors. The ganglion cells are the output neurons and carry all visual information from the retina to the brain. In addition to the signal flow mentioned above, recent studies suggest that retinal neurons are susceptible to central influences via centrifugal fibers and interplexiform cells (Stell et al., 1984 ; Umino et al., 1991). The aim of this project is to study the propagation of backward signal, mainly related to the receptive field property (see Umino et al., 1991) in the retina. The major results and findings are as follows. (1) A new type of light stimulator composed of cathode-ray-tube was developed to examine the receptive filed properties of retinal neurons. (2) Bipolar cells were electrically coupled via gap junctions. The electrical coupling of bipolar cells for … More ming the receptive field center, has the advantage of decreasing the dispersion of input signals from cones, and permits the decrease of spatial noise in bipolar cells. (3) The time-varying random square pattern of light signal was applied to the retina to study the receptive field properties in both the time and spatial domains. The cross correlation function between the light signal and the horizontal cells's response indicates that horizontal cells initially respond to light with their receptive field center and then the region, which can respond to light, is enlarged to surround. (4) After the intruduction of background light, the receptive filed properties of horizontal cells were unchanged. After the prolonged application of background light, however, the receptive field was gradually shrunk and leveled off. Thus, the shrinkage of the horizontal cell's receptive filed related to the light/dark adaptation can be involved in the function of the propagation of backward signal in thUmino & Dowling (1991a). Journal of Neuroscience 11, 3034-3046Umino.Lee & Dowling (1991b). Visual Neuroscience 7.451-458Stell et al., (1984) Proc Natl.Acad.Sci.USA.81 : 940-944 Less