Rangaswamy Nalini V, Shirato Suguru, Kaneko Muneyoshi, Digby Beth I, Robson John G, Frishman Laura J
University of Houston, College of Optometry, Houston, Texas 77204-2020, USA.
Invest Ophthalmol Vis Sci. 2007 Oct;48(10):4818-28. doi: 10.1167/iovs.07-0218.
To determine flash and background colors that best isolate the photopic negative response (PhNR) and maximize its amplitude in the primate ERG.
Photopic full-field flash ERGs were recorded from anesthetized macaque monkeys before and after pharmacologic blockade of Na(+)-dependent spiking activity with tetrodotoxin (TTX, 1 to 2 muM, n = 3), blockade of ionotropic glutamatergic transmission with cis-2,3 piperidine dicarboxylic acid (PDA, 3.3-3.8 mM, n = 3) or laser-induced monocular experimental glaucoma (n = 6), and from six normal human subjects. Photopically matched colored flashes of increasing stimulus strengths were presented on scotopically matched blue, white, or yellow backgrounds of 100 scot cd/m(2) using an LED-based stimulator.
PhNRs that could be eliminated by TTX or severe experimental glaucoma were present in responses to brief (<5 ms) and long-duration (200 ms) stimuli of all color combinations. In normal monkey and human eyes for brief low-energy flashes, PhNR amplitudes were highest for red flashes on blue backgrounds and blue flashes on yellow backgrounds. For high-energy flashes, amplitudes were more similar for all color combinations. For long-duration stimuli, the PhNR(on) at light onset in monkeys was larger for red and blue stimuli, regardless of background color, than for spectrally broader flashes, except for stimuli >17.7 cd/m(2) when PhNR(on)s were all of similar amplitude. For red flashes, eliminating the PhNR(on) pharmacologically or by glaucoma removed the slowly recovering negative wave that normally followed the transient b-wave and elevated the whole ON response close to the level of the b-wave peak. However, for white, blue, and green flashes, a lower-amplitude plateau that could be removed by PDA remained.
For weak to moderate flash strengths, the best stimulus for maximizing PhNR amplitude is one that primarily stimulates one cone type, on a background with minimal adaptive effect on cones. For stronger stimuli, differences in amplitude are smaller. For long-duration stimuli, red best isolates the PhNR(on) because it minimizes the overlapping lower-level plateau that originates from the activity of second-order hyperpolarizing retinal neurons.
确定能最佳分离明视负反应（PhNR）并使其在灵长类动物视网膜电图（ERG）中幅度最大化的闪光和背景颜色。
在使用河豚毒素（TTX，1至2 μM，n = 3）药理学阻断钠依赖性动作电位活动、用顺式 - 2,3 - 哌啶二羧酸（PDA，3.3 - 3.8 mM，n = 3）阻断离子型谷氨酸能传递或激光诱导单眼实验性青光眼（n = 6）前后，记录麻醉猕猴的明视全视野闪光ERG，并记录6名正常人类受试者的ERG。使用基于发光二极管的刺激器，在100 scot cd/m²的暗视匹配蓝色、白色或黄色背景上呈现光匹配的强度递增的彩色闪光。
对所有颜色组合的短暂（<5 ms）和长时间（200 ms）刺激的反应中都存在可被TTX或严重实验性青光眼消除的PhNR。在正常猴眼和人眼中，对于短暂低能量闪光，蓝色背景上的红色闪光和黄色背景上的蓝色闪光的PhNR幅度最高。对于高能量闪光，所有颜色组合的幅度更相似。对于长时间刺激，猴子在光开始时的PhNR（on），红色和蓝色刺激的幅度大于光谱更宽的闪光，无论背景颜色如何，除非刺激强度>17.7 cd/m²，此时PhNR（on）的幅度都相似。对于红色闪光，通过药理学方法或青光眼消除PhNR（on）会消除通常跟随瞬态b波的缓慢恢复的负波，并使整个ON反应升高至接近b波峰值的水平。然而，对于白色、蓝色和绿色闪光，存在一个可被PDA消除的较低幅度的平台期。
对于弱至中等闪光强度，使PhNR幅度最大化的最佳刺激是主要刺激一种视锥细胞类型的刺激，且背景对视锥细胞的适应性影响最小。对于较强刺激，幅度差异较小。对于长时间刺激，红色能最佳分离PhNR（on），因为它使源自二阶超极化视网膜神经元活动的较低水平平台期重叠最小化。
