Effects of Biological Maturation and Visual Experience on Human Visual Developmen

描述(申请人提供)：视觉发展在多大程度上受制于“先天”与“后天”，一直是视觉研究中的一个长期话题。尽管在过去的50年里，从动物研究中学到了很多东西，但人们对影响人类视觉发育的因素知之甚少。目前的提案调查了与视觉经验(后天培养)和预先编程的生物成熟(自然)相关的因素，或者两者都是重要的因素，以塑造视觉发展。为此，我们建议对四个不同的受试者群体进行视觉心理物理研究，梳理出这些因素。(A)足月儿和(B)健康早产儿。如果早期的视觉经验是视觉发育的主导力量，那么早产儿在绘制出生后年龄(即出生以来的年龄)时应该表现出与足月儿相同的发展轨迹。相比之下，如果生物成熟的影响更大，那么早产儿在怀孕后年龄(即自受孕以来的年龄)就应该与足月婴儿相匹配。(C)同卵双胞胎与异卵双胞胎。虽然这两种双胞胎都有相同的环境和父母，但他们在共同基因构成的程度上有所不同。我们应用了一个生物测定双胞胎模型，该模型可以确定视觉表现的“表型”差异的比例，这可以由共享的环境和基因来解释。(D)早期视觉输入异常的婴儿和儿童。在这一组(白内障、斜视和屈光参差)和健康对照组之间的比较将解决视觉处理的各个方面在发育早期对异常视觉体验的脆弱性。三个目标涉及不同水平的视觉加工：1)皮质下通路处理：我们询问三条主要的视网膜发生通路，即大细胞(M)、小细胞(P)和非细胞(K)，是否同样或不同地受到视觉经验的影响，获得对亮度、红/绿和蓝/黄刺激的对比敏感度，这些刺激被认为分别由这些通路介导。2)大脑皮层运动加工的皮质下输入：我们将使用“运动/检测”阈值比率范式，测量颜色(P通路)与亮度(M通路)对比度对运动加工的相对影响，从而获得对运动加工的P与M下通路输入的程度的估计。我们实验室以前的结果表明，运动的相对P和M输入随着年龄的增加而减少，在这里，我们将询问这种重新加权过程更多地受到视觉经验或生物成熟的影响。3)皮质运动处理：我们将评估全局运动处理，这被认为是更高级别的皮质功能。与以前的许多研究不同，我们的全局运动刺激将被调整到每个受试者的可检测性，这样可以更明确地解释跨年龄/受试者群体观察到的差异。这些项目的结果将揭示视觉发育的哪些方面更容易受到视觉体验的影响，这可能对治疗先天性眼病儿童具有重要意义。公共卫生相关性视觉发育在多大程度上受“本性”(即预先编程的生物成熟)与“后天”(即视觉经验)的控制一直是视觉研究中的一个长期主题。目前的提案通过在具有相关性的受试者人群中进行婴儿视觉心理物理研究来研究这个问题：早产儿、双胞胎婴儿和出生时患有先天性眼病的婴儿。我们希望这些研究的结果将揭示视觉发育的哪些方面更容易受到视觉体验的影响，这可能对治疗患有视觉障碍的儿童具有重要意义。

Description (provided by applicant): The degree to which visual development is governed by "nature" vs. "nurture" has been a long-standing topic in vision research. Although much has been learned from animal studies in the last 50 years, relatively little is known about the factors influencing visual development in humans. The current proposal investigates whether factors related to visual experience ("nurture") vs. preprogrammed biological maturation ("nature"), or both, are important in shaping visual development. To this end, we propose visual psychophysical studies with four different subject populations that tease apart these factors. (A) Fullterm Infants and (B) Healthy Preterm Infants. If early visual experience is the dominant force in visual development, preterm infants should show the same developmental trajectories as fullterm infants when plotted in terms of postnatal age (i.e. age since birth). By contrast, if biological maturation is more influential, preterm infants should match fullterm babies when plotted in postconceptional age (i.e., age since conception). (C) Monozygotic vs. Dizygotic Twins. While both twin types share the same environment and parents, they differ in the degree of shared genetic makeup. We apply a biometrical twin model that can identify the proportion of "phenotypic" variance in visual performance that can be accounted for by shared environment versus genes. (D) Infants and Children with Early Abnormal Visual Input. Comparisons made between this group (cataract, strabismus, and anisometropia) and healthy controls will address the vulnerability of various aspects of visual processing to abnormal visual experience early in development. Three aims address different levels of visual processing: 1) Subcortical Pathway Processing: We ask if the three main retinogeniculate pathways, Magnocellular (M), Parvocellular (P) and Koniocellular (K), are equally or differentially affected by visual experience, by obtaining contrast sensitivities for luminance, red/green and blue/yellow stimuli, thought to be mediated by these pathways, respectively. 2) Subcortical Input to Cortical Motion Processing: We will obtain an estimate of the extent of P vs. M subcortical pathway input to motion processing using a "Motion/Detection" threshold ratio paradigm that measures the relative effects of chromatic (P pathway) vs. luminance (M pathway) contrast on motion processing. Previous results from our laboratory suggest that the relative P vs. M input to motion decreases with age, and here we will ask whether this re-weighting process is influenced more by visual experience or biological maturation. 3) Cortical Motion Processing: We will assess global motion processing, which is believed to be a higher-level cortical function. Unlike many previous studies, our global motion stimuli will be scaled to detectability for each subject, such that differences observed across ages/subject groups can be more definitively interpreted. The results of these projects, which will reveal what aspects of visual development are more vs. less amenable to effects of visual experience, may have important implications for treating children with congenital eye disorders. PUBLIC HEALTH RELEVANCE The degree to which visual development is governed by "nature" (i.e., pre-programmed biological maturation) vs. "nurture" (i.e., visual experience) has been a long-standing topic in vision research. The current proposal investigates this question by conducting infant visual psychophysical studies in subject populations that bear relevance: preterm infants, twin infants and infants born with congenital eye disorders. The results of these studies, which we hope will reveal what aspects of visual development are more vs. less amenable to effects of visual experience, may have important implications for treating children with visual disorders.