The Evolutionary Origins of the Vertebrate Brain: Neural Organization and Complexity in Chondrichthyans

脊椎动物大脑的进化起源：软骨鱼的神经组织和复杂性

基本信息

批准号：
0850369
负责人：
Lawrence Frank
金额：
$ 76.6万
依托单位：
University of California-San Diego
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-01 至 2013-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=0850369&HistoricalAwards=false
关键词：
Evolutionary Origins Vertebrate Brain Neural

项目摘要

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."A common perception is that sharks are small-brained animals with a limited behavioral repertoire. Recent research has been dispelling these myths and has found that sharks possess brains that are of comparable size to birds and mammals. One brain structure of particular interest is the cerebellum, largely due to its extensive evolutionary history as well as the ongoing debate surrounding its function. This structure originally appeared in early sharks and has been carried through vertebrate evolution from the earliest cartilaginous fishes to the base of the human brain. However, the cerebellum and its function, from fish through to humans, has been an area of debate among neurobiologists. A large body of research asserts that the cerebellum controls and orchestrates movement while other research suggests that the primary function of the cerebellum is not movement, but is the acquisition and discrimination of sensory information. What can elasmobranchs (sharks, skates, and rays) contribute to our understanding of the human cerebellum and the origin of its function?Large variation exists in the size and convolution (or foliation) of the cerebellum across cartilaginous fishes, including sharks. Until recently, the variation in cerebellar complexity has only been qualitatively assessed by scoring surface structure on the basis of length and depth of the folds using the visual grading index. The output of these visual assessments has shown that the highest levels of foliation are found in agile predators that lived in open ocean (3D) environments, such as Isurus oxyrinchus (shortfin mako shark), Alopias vulpinus (thintail thresher shark), and Sphyrna mokarran (great hammerhead shark) and the lowest levels of foliation occur in slow-moving, passive predators such as Orectolobus maculatus (wobbegong shark), Squalus acanthias (spiny dogfish), Squatina angelus (angel shark). These preliminary ecological correlations with brain development suggest a functional basis for this characteristic. However, visual classification is limited, as it does not provide a quantitative method for characterization and comparison of foliation. To confirm these trends, which show that cerebellar complexity is correlated with ecological factors (primary habitats, with varying locomotory styles, reproductive modes, and prey capture strategies), a more quantitative approach is necessary.Magnetic resonance imaging (MRI) is unique in its ability to non-invasively acquire high-resolution data from soft tissue structure and Diffusion Tensor Imaging (DTI) is an MRI method that provides information on the orientation and coherence of white matter fiber tracts, thereby facilitating the reconstruction of neural fiber pathways. This project aims to utilize microscopic anatomical MRI and microscopic DTI in conjunction with novel analysis methods (shape analysis and fiber tract mapping) to assess the degree of folding in the cerebellum and how this relates to diversification and proliferation of fiber tract pathways from this brain structure to other neural processing centers. Through these methods, the team will inform the debate on cerebellar function, provide rationale for the evolution of cerebellar foliation in cartilaginous fishes, and explore the extent to which adaptive, developmental, and phylogenetic processes are driving neural evolution.Publications, results, databases, and tools will be disseminated to the research community and general public via the existing Digital Fish Library website (www.digitalfishlibrary.org).

“该奖项是根据2009年的《美国复苏与再投资法》（公法111-5）资助的。“一个普遍的看法是，鲨鱼是行为库有限的小脑动物。最近的研究一直在消除这些神话，发现鲨鱼的大脑与鸟类和哺乳动物相当。一个特别感兴趣的大脑结构是小脑，主要是由于其广泛的进化史以及围绕其功能的持续辩论。这种结构最初出现在早期的鲨鱼中，并通过脊椎动物的进化从最早的软骨鱼到人脑的底部。然而，从鱼到人类的小脑及其功能一直是神经生物学家之间的争论领域。大量研究断言，小脑控制和策划运动，而其他研究表明小脑的主要功能不是运动，而是对感官信息的获取和歧视。弹性（鲨鱼，溜冰鞋和射线）可以有助于我们对人类小脑的理解及其功能的起源？在包括鲨鱼在内的软骨鱼类中，小脑的大小和卷积（或叶子）存在着大的变化。直到最近，只有使用视觉分级指数根据折叠的长度和深度来评估表面结构，小脑复杂性的变化才得到定性评估。 The output of these visual assessments has shown that the highest levels of foliation are found in agile predators that lived in open ocean (3D) environments, such as Isurus oxyrinchus (shortfin mako shark), Alopias vulpinus (thintail thresher shark), and Sphyrna mokarran (great hammerhead shark) and the lowest levels of foliation occur in slow-moving, passive predators such as Orectolobus MacUlatus（Wobbegong鲨鱼），Squalus Acanthias（刺狗鱼），Squatina Angelus（Angel Shark）。这些与大脑发育的初步生态相关性提出了这种特征的功能基础。但是，视觉分类是有限的，因为它不能为叶面的表征和比较提供定量方法。为了确认这些趋势，这些趋势表明，小脑复杂性与生态因素（主要栖息地，具有不同的运动样式，生殖模式和猎物捕获策略）相关，因此需要更定量的方法。磁共振成像（MRI）在非交易中获得高度组织的能力与柔软的组织数据无关，并在MRM MRM MRM MIR中差异很独特。提供有关白质纤维区域方向和连贯性的信息，从而促进神经纤维途径的重建。该项目旨在利用微观解剖学MRI和微观DTI与新颖的分析方法（形状分析和纤维图形映射）结合使用，以评估小脑中的折叠程度，以及这与从这种大脑结构到其他神经处理中心的多样化和纤维轨道途径的多样化和增殖。通过这些方法，团队将为小脑功能的辩论提供辩论，为软骨鱼类中小脑叶的演变提供理由，并探索自适应，发育和系统发育过程的程度，促进神经的进化。（www.digitalfishlibrary.org）。