Plasticity of development of vision and of the mammalian visual pathways

视觉发育和哺乳动物视觉通路的可塑性

• 批准号: RGPIN-2015-03819
• 负责人: Mitchell, Donald
• 金额: $ 2.4万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612592
• 关键词: Plasticity; development; vision; mammalian; visual

The objective of my research is to understand how the development of the pathways in the brain that process vision, and vision itself, is influenced by what an animal sees early in life, the so-called nature-nuture issue with respect to vision. From studies on animal species that have visual systems organized like ours for accurate binocular depth perception (stereoscopic vision), it is known that there are so called “critical periods” in development during which abnormal visual input can effect the development of the visual pathways that result in visual impairments. More recently it has been shown that prior to birth the anatomical organization of the visual system develops according to a series of genetic instructions to a level that can be quite sophisticated. The blueprint established by genetic instructions provides the template that both allows and constrains the extent to which visual experience after birth can further influence development. A few years ago I introduced a new method to examine the role of experience in development by sequentially pitting two visual inputs against each other each day. For part of the day animals receive normal visual input while for the remainder they receive grossly abnormal input, in the form of visual input to just one eye. The first visual input matches the anatomical template established by genetic instruction at birth, while the other input does not. We reasoned that visual input that matches the template at birth would be favoured over the other. The results clearly favour this possibility; binocular visual input that amounted to just 30% of the total exposure outweighed or protected against much longer daily periods of monocular exposure to permit the development of normal visual acuity in both eyes as well normal appearance of the visual cortex. The same strategy will be used to establish the far more strict requirements for development of normal stereoscopic vision, the ability to use information from the two eyes to provide a vivid impression of depth as in 3-D movies. Another study will examine the requirements for development of normal visual acuity and stereoscopic vision in the presence of intermittent misalignment of the two eyes as occurs in strabismus (a” turned eye”) that will be simulated with prisms. We will follow-up to a recent unexpected finding of ours, that kittens placed in total darkness for 10 days before the age of 11 weeks suffer a severe but temporary loss of vision by determining some of the conditions such as the length of darkness under which this effects occur. As in my past studies, the vision of each eye for these various studies is evaluated by use of a jumping stand where kittens are required to jump for a food reward and petting to one of two stimuli placed side by side below them.

我的研究的目的是了解如何在大脑中的途径发展，即过程视觉和视觉本身如何受动物生命早期所见的影响，即关于视觉的所谓自然 - 苏联问题。从对具有像我们这样的视觉系统组织的动物物种进行的研究，以进行准确的双目深度感知（立体视觉），众所周知，在发育中，所谓的“关键时期”所谓的“关键时期”，在此期间，异常的视觉输入可以影响导致视觉障碍的视觉途径的发展。最近，已经表明，在出生前，根据一系列遗传说明的解剖学组织，可以非常复杂。通过遗传指示建立的蓝图提供了一个模板，该模板既允许并约束出生后的视觉体验可以进一步影响发展的程度。几年前，我引入了一种新方法，以每天将两个视觉输入相互依次依次，以检查经验在发展中的作用。在一天的一部分中，动物会接受正常的视觉输入，而在其余部分中，它们以视觉输入的形式获得了严重的异常输入。第一个视觉输入与出生时遗传学指导建立的解剖模板匹配，而另一输入则与其他输入相匹配。我们认为，与出生时模板相匹配的视觉输入会比对方相比受到青睐。结果显然有利于这种可能性；双眼视觉输入仅占总暴露量的30％，超过或保护了更长的每日单眼暴露时期，以允许眼睛的正常视力以及视觉皮层的正常出现。将使用相同的策略来建立更严格的正常立体视力的要求，即使用两只眼睛的信息来提供生动的深度印象，就像3-D电影中一样。另一项研究将研究在两只眼睛之间存在间歇性未对准的情况下，正常视力和立体视觉的发展，就像斜视（a“转眼”）将被棱镜模拟。我们将跟进我们最近的意外发现，即小猫在11周龄之前将其完全黑暗置于10天中，遭受了严重但暂时的视力丧失，通过确定某些条件（例如发生这种影响的黑暗长度）。与我过去的研究一样，每只眼睛对这些各种研究的视野都可以使用跳跃架来评估需要小猫来跳跃以获得食物奖励，并抚摸着下方并排放置的两个刺激之一。