Influences of ecological niche on mechanisms of visual pathway maturation

生态位对视觉通路成熟机制的影响

• 批准号: 2029980
• 负责人: Sarah Pallas
• 金额: $ 57.26万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-10-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2029980&HistoricalAwards=false
• 关键词: Influences; ecological; niche; mechanisms; visual

The connections between nerve cells in juvenile brain networks are flexible and can be shaped by the environment and experience. Network stability increases with age, producing both costs and benefits. Different species have evolved distinct patterns of plasticity reduction. This project compares developmental changes in visual system plasticity across several mammalian species. It will reveal how early sensory experience influences the way brain circuits are put together, and how ongoing sensory stimulation maintains the boundary between stability vs. flexibility of neural circuits. Because the genomes of many mammals have now been sequenced, it is possible to employ genetic manipulations that until recently were only feasible in mice. Comparative work is necessary to arrive at a more complete understanding of plasticity mechanisms and to determine whether animals with better vision and more reliance on visual perception for survival than mice (the current species of choice) might provide a better animal model for human visual development. Taken together, the results of the study will provide important mechanistic information about how and why the brain develops and changes with experience, and which animal models are the most relevant for biomedical research. Understanding the natural processes that control the boundary between plasticity and stability make it possible to manipulate that boundary for human benefit. Results from this study will also provide basic information about neural network plasticity which may be useful for designing drug and rehabilitative therapies to treat or repair diseases or injuries of visual pathways specifically, and brain pathways in general.Visual experience during an early critical period is required for normal development of visual cortical (V1) structure and function in carnivores and non-human primates. Mice are now the preferred animal model for studies of visual pathway development and plasticity. Visual development and plasticity of mice differs from that of primates in both known and unknown ways that may have important consequences for the generalization of research findings to humans. Previous visual deprivation studies in hamsters and mice from the P.I.'s lab have shown that early visual experience is not required for normal developmental refinement of receptive fields in visual midbrain and visual cortex. Instead, vision is necessary only for the maintenance of normal function in visual midbrain (SC) and V1 of adults. The hypothesis to be tested in this study is that the degree to which a species' visual system development depends on visual experience is influenced by the extent to which vision is important in their ecological niche. The predicted outcome is that nocturnal species whose young stay in a burrow (such as mice) will be less dependent on vision to shape the development of their visual pathways than diurnal species whose young spend more time above ground. The timing and level of sensitivity to visual experience will be measured in several rodent species that differ in their daily activity patterns, nesting habits, and ecological niche. The rodent data will be compared to that from a carnivore species that has traditionally been used in studies of visual system development and plasticity.

青少年大脑网络中神经细胞之间的联系是灵活的，可以由环境和经验塑造。网络稳定性随着年龄的增长而增加，产生成本和收益。不同的物种进化出不同的可塑性减少模式。本项目比较了几种哺乳动物视觉系统可塑性的发育变化。它将揭示早期的感官体验如何影响大脑回路的组合方式，以及持续的感官刺激如何维持神经回路的稳定性与灵活性之间的界限。由于许多哺乳动物的基因组现在已经被测序，因此有可能采用直到最近才在老鼠身上可行的基因操作。为了更全面地了解可塑性机制，并确定视力更好、比小鼠（目前选择的物种）更依赖视觉感知生存的动物是否可能为人类视觉发育提供更好的动物模型，比较研究是必要的。总的来说，这项研究的结果将提供关于大脑如何以及为什么随着经验而发展和变化的重要机制信息，以及哪种动物模型与生物医学研究最相关。了解控制可塑性和稳定性边界的自然过程，就有可能为人类利益操纵这一边界。本研究的结果也将提供神经网络可塑性的基本信息，这可能有助于设计药物和康复疗法来治疗或修复视觉通路的疾病或损伤，以及一般的大脑通路。在食肉动物和非人灵长类动物中，早期关键时期的视觉经验是视觉皮层（V1）结构和功能正常发育所必需的。小鼠是目前研究视觉通路发育和可塑性的首选动物模型。小鼠的视觉发育和可塑性在已知和未知的方面都不同于灵长类动物，这可能对研究结果在人类中的推广产生重要影响。先前在P.I.的仓鼠和小鼠中进行的视觉剥夺研究他的实验室已经证明，早期的视觉经验对于视觉中脑和视觉皮层的接受野的正常发育完善并不是必需的。相反，视觉只是维持成人视觉中脑（SC）和V1的正常功能所必需的。本研究要验证的假设是，一个物种的视觉系统发展依赖于视觉经验的程度受到视觉在其生态位中重要程度的影响。预测的结果是，夜间活动的物种，其幼仔待在洞穴中（如老鼠）将较少依赖于视觉来塑造其视觉路径的发展，而白天活动的物种，其幼仔花更多的时间在地面上。对视觉体验的时间和敏感程度将在几种啮齿动物中进行测量，这些啮齿动物的日常活动模式、筑巢习惯和生态位不同。啮齿动物的数据将与食肉动物的数据进行比较，食肉动物的数据传统上用于视觉系统发育和可塑性的研究。