RECEPTOR-RELATED NONLINEARITIES IN PHOTOPIC VISION

(改编自申请人的摘要)本研究的目的是 对明视检测和光线模型进行量化和实证评估 适应。这些实验结合了两种方法来研究 照片敏感度：“适应”和“色觉”方法。 前者使用探头闪光检查中心凹的检测和适应 范例。增量阈值是针对一个简短目标( “探测器”)呈现在一个闪光的区域(“闪光”)上，视觉 系统还没来得及适应。探测器闪光技术揭示了 锥体系统中的非线性，在稳态场中不明显。 在色觉方法中，最初制定的模型是为了解释 将颜色外观应用于灵敏度数据。这些模型假设 光的可探测性取决于它在三个月内所引起的活动。 通道或通道。这些通道包括两个相对的色度通道 (红/绿和黄/蓝)和一条非对抗性消色通道。 探头-闪存数据已与包含单个静态 非线性。虽然这些数据很容易用这样的模型来描述，但该网站 视觉通路中敏感度丧失的原因尚不清楚。 心理物理学家最初认为这些数据反映了非线性。 在视锥感受器内。然而，各种衡量标准表明， 在许多情况下，脱敏发生在受体之外，并且 牵涉到暗中对立的机制。 一个双部位模型被开发来解释后的证据 探头闪光数据中的受体非线性。当前提案的一个目标 就是制定一个模型来预测适应变化的影响 强度。第二个目标是比较静态非线性 从心理生理上推断为灵长类生理学。最近录制的 灵长类锥体响应函数为直接 受体生理和行为的比较。 在长波长和短波长锥形路径中的灵敏度将是 检查过了。后者提供了一个有价值的研究主题，因为它 对视网膜疾病的相对易感性。获取的探头闪存数据 这些患者产生了一些分歧，即是否观察到 敏感度的下降反映了受体或受体后缺陷。通过 分离正常观察者的受体和对手的非线性，以及 将结果与灵长类受体数据进行比较，可以深入了解 可获得某些临床人群的敏感度丧失部位。

(Adapted from the applicant's abstract) The aim of the present study is to quantify and empirically evaluate a model of photopic detection and light adaptation. The experiments combine two approaches to the study of photopic sensitivity: the "adaptation" and the "color vision" approaches. The former examines foveal detection and adaptation with the probe-flash paradigm. Increment thresholds are measured for a brief target (the "probe") presented upon a flashed field (the "flash) to which the visual system has not had time to adapt. The probe flash techniques reveals nonlinearities in the cone system that are not evident with steady fields. In the color vision approach, models originally formulated to explain color appearance are applied to sensitivity data. The models assume that the detectability of a light depends on the activity it elicits in three pathways or channels. These include two opponent chromatic channels (red/green and yellow/blue) and one nonopponent achromatic pathway. Probe-flash data have been fit with models containing a single static nonlinearity. While the data are easily described by such models, the site of sensitivity loss within the visual pathway remains unclear. Psychophysicists initially assumed the data reflected nonlinearities within the cone receptors. However, a variety of measures reveal that under many conditions, desensitization occurs beyond the receptors, and involves spectrally opponent mechanisms. A two-site model was developed to account for the evidence of post- receptor nonlinearities in probe-flash data. One aim of current proposal is to formulate a model that predicts the effects of changes in adapting intensity. A secondary goal is to compare the static nonlinearities inferred psychophysically to primate physiology. Recent recordings of primate cone response functions provide a new opportunity for direct comparison between receptor physiology and behavior. Sensitivity in both long- and short-wavelength cone pathways will be examined. The latter provides a valuable subject of study because of its relative vulnerability to retinal disease. Probe-flash data obtained for these patients have generated some disagreement as to whether the observed falloff in sensitivity reflects receptor or post-receptor deficits. By isolating receptor and opponent nonlinearities in normal observers, and comparing the results to primate receptor data, some insights into the locus of sensitivity loss in certain clinical populations can be gained.