Brain Size Plasticity in Anamniote Vertebrates

拟南蚓脊椎动物大脑大小的可塑性

• 批准号: RGPIN-2020-04114
• 负责人: Laberge, Frederic
• 金额: $ 2.04万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739672
• 关键词: Brain; Size; Plasticity; Anamniote; Vertebrates

Brains vary enormously in size, cell density and connectivity. My long-term research goal is to understand how variation in brain structure and size influences organismic function to help identify the factors that drive evolution and plasticity of the nervous system. Fishes and amphibians (i.e. anamniote vertebrates) have a widespread and lifelong ability to produce new brain cells and thus are good models to study the factors determining brain size. Here, we will investigate the cellular mechanisms underlying brain size flexibility and its impacts on cognition using both lab- and field-based approaches. Compelling evidence of adult brain size flexibility in vertebrates is lacking, but our preliminary evidence acquired in the past year suggests that adult fish show changes in relative brain size across seasons and upon escape from captivity into the wild. Unlike birds and mammals, adult fish and amphibians have a widespread ability to produce new brain cells and thus are good candidates to display brain size flexibility. We will first investigate competing hypotheses explaining seasonal changes in brain size in adult anamniotes: the `energy savings', `sensory reorganization', and `reproductive effort' hypotheses. To test the energy savings hypothesis, artificial hibernation of fire-bellied toads under laboratory conditions will be used to measure variation in relative brain size and energy expenditure during simulated seasonal change. The sensory reorganization and reproductive effort hypotheses will be investigated by assessing variation in the size of brain regions with known functions across seasons in wild fish differing in maturation status. Second, we will elucidate the cellular mechanisms responsible for change in brain size. Changes in brain size could involve modulation of the rates of birth of neural stem cells, differentiation of new neurons and glia from stem cells, and/or cell death. Markers for these processes will be measured by stereology analysis on brain sections of fish sampled across seasons and toads sampled across phases of artificial hibernation. Additionally, the number and density of neurons and non-neuronal cells will be obtained using cell counting methods. Finally, the relevance of changes in brain size to cognition and behaviour will be tested. Investment in brain tissue should increase cognitive performance, which will improve the performance of animals tested in behavioural tasks that engage cognitive abilities. We will use prey catching conditioning tasks with fire-bellied toads to study cognitive abilities related to learning and behavioural flexibility. The proposed work will tackle the controversial relationship between brain size, neuron number, and cognitive capacity. Additionally, it will support more applied concerns relevant to many stakeholders, such as helping to develop indicators of behavioural performance and energetic status in aquatic wildlife for environmental monitoring of Canadian watersheds.

大脑在大小、细胞密度和连通性上差异巨大。我的长期研究目标是了解大脑结构和大小的变化如何影响器官功能，以帮助确定驱动神经系统进化和可塑性的因素。鱼类和两栖动物（即脊椎动物）具有广泛和终身产生新脑细胞的能力，因此是研究决定大脑大小的因素的良好模型。在这里，我们将研究大脑大小灵活性的细胞机制及其对认知的影响，使用实验室和现场为基础的方法。脊椎动物成年大脑大小灵活性的令人信服的证据是缺乏的，但我们在过去一年中获得的初步证据表明，成鱼在不同季节和从圈养环境中逃到野外时，大脑的相对大小会发生变化。与鸟类和哺乳动物不同，成鱼和两栖动物具有产生新脑细胞的广泛能力，因此是显示大脑大小灵活性的良好候选者。我们将首先调查竞争的假设解释在成年anabolotes大脑大小的季节性变化：“节能”，“感觉重组”和“生殖努力”的假设。为了验证节能假设，将在实验室条件下对火腹蟾蜍进行人工冬眠，以测量模拟季节变化期间相对大脑大小和能量消耗的变化。感官重组和生殖努力假说将通过评估不同成熟状态的野生鱼类不同季节的已知功能的大脑区域大小的变化来研究。其次，我们将阐明负责大脑大小变化的细胞机制。大脑大小的变化可能涉及调节神经干细胞的出生率，从干细胞分化出新的神经元和神经胶质细胞，和/或细胞死亡。这些过程的标记将通过对不同季节的鱼和不同人工冬眠阶段的蟾蜍的大脑切片进行体视学分析来测量。此外，将使用细胞计数方法获得神经元和非神经元细胞的数量和密度。最后，将测试大脑大小变化与认知和行为的相关性。对脑组织的投资应该会提高认知能力，这将提高动物在涉及认知能力的行为任务中的表现。我们将使用猎物捕捉条件反射任务与火腹蟾蜍研究认知能力相关的学习和行为的灵活性。 这项工作将解决大脑大小、神经元数量和认知能力之间有争议的关系。此外，它还将支持与许多利益攸关方有关的更多应用关切，例如帮助制定水生野生动物行为表现和活力状况指标，用于加拿大流域的环境监测。