ROD-CONE INTERACTION IN CARP RETINA: AN ANALYSIS OF ELECTRORETINOGRAPHIC B-WAVES

Changes in electroretinographic b-wave in the presence of background lights of increas-ing intensity were examined in isolated, superfused carp retinas. Within a certain range ofambient illumination b-waves elicited by red (695 nm) test flashes against dimmer backgroundlights were smaller in size than against brighter ones. Accordingly, incremental thresholdsfor red flashes decreased as the intensity of background lights increased within this intensityrange. The results suggest that cone pathways may be suppressed by rods in darkness anddim illumination. The phenomenon was absent for photoreceptor potentials(PⅢ components),indicating that the rod-cone interaction occurs in second-order retinal neurons.     

虎蝾螈视网膜水平细胞接收的光感受细胞的突触输入

本文在虎蝾螈分离视网膜上研究了水平细胞接收的来自视杆和视锥的突触输入,并考察了在暗、明适应条件下视杆、视锥及水平细胞的反应振幅-光强曲线。光谱敏感性和反应波形。水平细胞在暗、明适应条件下均接收来自视杆、视锥的混合输入。两种光感受器输入的相对比例随细胞而异,并取决于刺激光和背景光的强度。     

鲫鱼C型水平细胞接收的感受细胞输入

本文以在位鲫鱼视网膜为标本用细胞内记录技术分析了R/G型水平细胞的感受细胞输入。对反应不同时相测定的光谱敏感性的分析表明,R/G型细胞反应的超极化成分系来自绿敏锥细胞的输入所产生。这种输入和另一种引起细胞去极化反应的对长波敏感的输入在R/G型细胞近似呈线性综合。据此,发展了一种代数学方法来分离该型细胞反应中的去极化成分。对这种分离的去极化成分的光谱敏感性的测定表明,它系来自红敏锥细胞的输入所引起,并非某种对深红波段敏感的假想的感受细胞的输入作用所致。     

PHOTORECEPTOR INPUTS CONVERGING ONTO C-TYPE HORIZONTAL CELLS OF THE RETINA OF CRUCIAN CARP

Responses of R/G-type horizontal cells recorded intracellularly in eye cup preparations with normalcirculation of crucian carp under dark-adapted conditions were studied and photoreceptor inputs convergingonto them were identified. Spectral sensitivities of the hyperpolarizing component of responses, determinedat different phases, suggested that it was produced by input from green-sensitive cones. This input andinput from long wavelength sensitive cones, causing depolarization of cells, were almost linearly sum-mated. Based on the linear summation assumption, an algebraic procedure was developed to isolate thedepclarizing component from responses of R/G-type cells to flashes at wavelengths longer than 540 nm.Spectral sensitivities of the isolated depolarizing component were determined and agreed reasonably wellwith those of red-sensitive cones. Therefore, it is unlikely that depolarization of R/G-type cells maybe due to input from some presumptive deep-red sensitive cones.     

视网膜C型水平细胞的计算机辅助定量形态研究

本文应用计算机辅助三维重构技术,对鲫鱼视网膜中用辣根过氧化物酶(HRP)作胞内染色的双相性C型水平细胞的形态学特征进行了定量的研究。测定了表征细胞形态学特性的若干参数,并在不同的亚型之间作了比较。结果表明,胞体面积和细胞的水平扩展度是两个特征参数,可以把不同亚型的C型水平细胞清楚地加以区分。     

SYNAPTIC INPUTS FROM RODS AND CONES TO HORIZONTAL CELLS IN THE TIGER SALAMANDER RETINA

Synaptic inputs from rods and cones to horizontal cells (HCs) were studied in the flatmounted isolated retinas of the tiger salamander. Voltage-intensity relations, spectral sensitivities and response waveforms of the rod, the cone, and the HC under dark- and light-adapted conditions were examined. HCs receive mixed inputs from rods and cones in both dark- and light-adapted retinas. The relative rod/cone input in HC_s depends on the intensity of stimulus and background illumination, and it varies from HC to HC.     

鱼视网膜水平细胞的暗适应特性

本文在完整的鲤鱼眼杯标本上,应用细胞内记录技术系统地考察了视杆和视锥水平细胞的暗适应特性,并与同时记录的视网膜电图b波进行了比较,视杆水平细胞的光反应性随暗适应时间的增长而逐渐增高,在60min后趋于稳定,与b波的变化相似;但视锥水平细胞的光反应性除在暗适应初始期有所增高外,之后随时间而逐渐降低,在暗适应150min时,对强光反应的极大振幅仅为几毫伏,表明这些细胞在长时间暗适应后受到强烈的压抑。     

A COMPUTER-ASSISTED STUDY OF QUANTITATIVE MORPHOLOGICAL FEATURES OF C TYPE HORIZONTAL CELLS IN RETINA

Biphasic C type horizontal cells of the retina of crucian carp were intracellularly stained with horse-radish peroxidase (HRP) and quantitatively studied with computer-aided three-dimensional reconstructiontechniques. Several parameters characterizing their morphology were determined and compared among different subtypes of horizontal cells. The results show that both cell body area and horizontal extensionare proper parameters by which different subtypes of biphasic horizontal cells can be clearly classified.     

鲫鱼视杆和视锥系统的相互作用——视网膜电图b波分析

本文在分离、灌流的鲫鱼视网膜上考察了视网膜电图b波随背景光强递增所发生的变化。在视杆、视锥同时活动的间视状态,较弱背景光时695nm闪光所引起的b波振幅反而低于较强背景光时同一闪光引起的b波。与此相应,695nm辨增阈在这一光强范围随背景光强递增而降低。这些结果提示,视锥信号在暗中和弱背景光强时受到视杆信号的压抑。光感受器电位(PⅢ)并不显示类似的变化,这表明视杆、视锥系统的这种相互作用发生在视网膜第二级神经元。     

一种新的C型水平细胞的鉴定

本文用在位鲫鱼视网膜标本从形态和生理上鉴定了一种新型的双相性水平细胞。与R/G型细胞相似,这种细胞也对短波和长波光刺激分别呈超极化和去极化反应,但极性的翻转约在560nm处。对超极化和去极化反应的光谱敏感性的测定表明,它们系分别源自蓝敏和绿敏锥细胞的输入,故称为G/B型细胞。这两种输入并非线性综合,而是呈现独特的相互作用。用HRP作胞内染色表明G/B型细胞的胞体和树突范围较小,在形态上迥然不同于R/G型细胞。