INFORMATION TRANSFER AND CONTRAST SENSITIVITY

这项建议旨在更好地了解 哺乳动物中央视觉通路的组织，以及 试图将视觉功能与神经元群联系起来 灵长类。我将集中讨论两个主要问题：1)什么是 最新的对比度增益控制的动态特性 在外侧膝状体(LGN)中发现？和2)什么 是心理生理决定的人的神经基础吗 亮度和颜色对比敏感度？ 第一个问题源于LGN是一种 对传入的视网膜信息进行动态过滤，并且其 视网膜输入的过滤(衰减)随刺激而增加 对比度。这一观察结果导致了一系列新的实验， 图案的对比度在时间上被调制。这就做 在麻醉和瘫痪的猫和猴子中记录 单个LGN细胞及其视网膜输入的反应 (记录为突触(S)电位)，并测量时间进程 由此，LGN调整其传输率(LGN 反应/视网膜反应)。 时间和空间刺激参数的重要性，如 以及视网膜偏心和双眼相互作用，将 都是可以探索的。 第二个问题是由于观察到在 猴LGN小细胞神经细胞(及其驱动，P 单元格)对亮度对比度的敏感度远低于 大细胞神经元(或视网膜M细胞)，最近 比较对比的心理物理工作(Mullen，1985) 人类对颜色和亮度图案的敏感性。这就做 确定哪些神经元群体可以解释这些 结果通过测量单个P细胞和M细胞的反应 猴子LGN对亮度和彩色图案都有影响。这就做 也测量感受器视野中心和感受器的灵敏度 从外围到亮度和颜色调制，以揭示 对颜色刺激的响应无限制增加的原因 与刺激大小，在P细胞中记录，和来源 M细胞和P细胞之间的对比度增益差异。结果是 将阐明M细胞和P细胞在脑内的功能 灵长类动物的视力。

This proposal aims at a better understanding of the functional organization of the central visual pathways of mammals, and attempts to relate visual functions to neuronal populations in the primate. I will focus on two main problems: 1) What are the dynamic properties of the contrast gain control we recently discovered in the Lateral Geniculate Nucleus (LGN)? and 2) What is the neural substrate for the psychophysically determined luminance and color contrast sensitivities? The first question stems from the observations that the LGN is a dynamic filter of the incoming retinal information, and that its filtering (attenuation) of retinal input increases with stimulus contrast. This observation lead to a set of new experiments, in which the contrast of a pattern is modulated in time. I will record in anesthized and paralyzed cats and monkeys the responses of single LGN cells together with their retinal input (recorded as synaptic (S) potentials), and measure the time course with which the LGN adjusts its transmission ratio (LGN response/retinal response) following a step increase in contrast. The importance of temporal and spatial stimulus parameters, as well as that of retinal eccentricity and binocular interactions, will all be explored. The second question is stimulated by the observation that in the monkey LGN the parvocellular neuons (and their drives, the P cells) are much less sensitive to luminance contrast than the magnocellular neurons (or the retinal M cells), and by recent psychophysical work (Mullen, 1985) which compared the contrast sensitivity for color and luminance patterns in humans. I will establish which neuronal population could account for these results by measruing the responses of single P and M cells in the monkey LGN to both luminance and chromatic patterns. I will also measure the sensitivities of the receptor field center and periphery to luminance and color modulations, to uncover the reason for the unbounded increase in response to color stimuli with stimulus size, noted in the P cells, and the source of the difference in contrast gain between M and P cells. The results will shed light on the function of the M cells and P cells in primate vision.