Plasticity of development of vision and of the mammalian central visual pathways

我的研究计划的主要目标是了解大脑中处理视觉的通路的发展，因此视觉本身是如何受到动物早期所见的影响的。从对猴子和小猫等动物物种的研究中得知，在发育过程中，存在所谓的“关键期”，在此期间，异常或有偏见的视觉输入可能会对视觉通路的发展产生永久性影响，而视觉通路的发展反过来又会导致视觉障碍。由一段不正常的早期视觉输入引起的视觉通路的改变现在被认为是常见的(约占总人口的3%)发育性视觉障碍弱视(懒眼)的基础，弱视的定义是非源于眼睛本身的视力低下。我进行的实验通过研究某些形式的异常输入如何影响猫的视觉，包括它们感知运动的能力，用头和眼睛跟随移动的物体，以及用一只爪子攻击它们，来探索这种疾病的根源。大多数实验包括通过使用视觉显示器和类似于测试弱视人类视力的任务来评估小猫的视力。实验的一个中心主题是，并不是所有的视觉输入在发育过程中都得到平等对待；当两只眼睛同时看到相同的东西时，短暂的正常双眼输入优先加权，以防止弱视的发展，即使大多数视觉输入严重异常。我将研究双眼输入的临界量是由正常输入的比例决定的，还是由这种输入的绝对量决定的。此外，我将研究将异常投入划分为单独的情节是否会削弱其有效性。

The major objective of my research program is to understand how the development of the pathways in the brain that process vision, and hence vision itself, are influenced by what an animal sees early in its life. From studies on animal species such as monkeys and kittens that have visual systems organized for accurate binocular depth perception (stereoscopic vision) like that of humans, it is known that there are so called "critical periods" in development during which abnormal or biased visual input can have a permanent effect on the development of the visual pathways which in turn result in visual impairments. The altered development of the visual pathways induced by an episode of abnormal early visual input is now thought to underlie the common (~3% of the population) developmental visual disorder called amblyopia ("lazy eye"), that is defined as poor vision that does not originate in the eye itself. The experiments I conduct explore the origins of this disorder through studies of how certain forms of abnormal input influence the vision of cats including their ability to perceive motion, to follow moving objects with their head and eyes and to strike at them with one of their paws. The majority of the experiments involve evaluations of the vision of the kittens by use of visual displays and tasks similar to those used to test the vision of amblyopic humans. A central theme of the experiments is the idea that not all visual input is treated equally during development; brief periods of normal binocular input where the two eyes see the same thing simultaneously, are weighted preferentially to prevent the development of amblyopia even when most visual input is grossly abnormal. I will examine whether the critical amount of binocular input is determined by the proportion of input that is normal or by an absolute amount of such input. In addition, I will examine whether division of the abnormal input into separate episodes will weaken its effectiveness.