DEVELOPMENT OF HYPERACUITY IN HUMAN INFANTS

成人视觉系统的复杂性和能力是 相当了不起。或许同样令人印象深刻的是这一过程 这些能力是在第一个阶段发展和完善的 几年的生命。本提案中描述的实验包括 关于这一关键方面的先前研究的延伸 发展，大脑皮质视觉加工的发展。 具体地说，定向调整的成熟将是 在人类婴儿中使用电生理和 心理物理技术。 四种不同的视觉诱发电位(VEP)实验和 三项心理物理研究，使用优先注视(PL)或 将进行视动性眼震(OKN)检查。蒙面， 适应、交叉定向抑制与定向 双目互动的调谐将被用来检查 取向选择性的发展。通过比较 定向选择性与定向选择性的发展时间进程 游标敏锐度，应该可以确定是否 游标敏锐度的发展(也被认为代表着 皮质过程)取决于或以某种方式与 定向调谐的发展。线与线之间的关系 检测阈值和游标敏锐度也将在 婴儿。这些实验不仅与我们的 对发展的认识，也可能提供证据 关于游标敏锐度背后的机制。这个 定向研究也可能提供间接证据，说明 参与大脑皮层发育的高级皮层突起 运动分析。因为正常发育很容易改变 在快速变化的时期，理解正常的视觉 发展对理解各种 视力异常(如弱视和斜视)。

The complexities and capabilities of the adult visual system are quite remarkable. Perhaps equally impressive is the process by which these abilities are developed and refined during the first few years of life. The experiments described in this proposal are an extension of previous research on one critical aspect of this development, the development of cortical processing of vision. Specifically, the maturation of orientation tuning will be investigated in human infants using both electrophysiological and psychophysical techniques. Four different visually evoked potential (VEP) experiments and three psychophysical studies using preferential looking (PL) or optokinetic nystagmus (OKN) will be conducted. Masking, adaptation, cross orientational inhibition, and the orientation tuning of binocular interactions will be used to examine the development of orientation selectivity. By comparing the developmental time course of orientation selectivity with that of vernier acuity, it should be possible to determine if the development of vernier acuity (also believed to represent a cortical process) depends on, or is in some way linked to, the development of orientation tuning. The relationship between line detection thresholds and vernier acuity will also be explored in infants. These experiments have relevance not only to our understanding of development, but also may provide evidence regarding the mechanisms underlying vernier acuity. The orientation studies may also provide indirect evidence about the development of higher order cortical processes involved in the analysis of motion. Since normal development is easily altered during periods of rapid change, understanding normal visual development have important implications for understanding various anomalies of vision (e.g., amblyopia and strabismus).