Organization of the telencephalon in lungfish

申请人建议对肺鱼的大脑进行实验，以确定它们是否与所有陆地脊椎动物（包括人类）的祖先最接近。大脑的组织，特别是前脑的组织，为动物的生物学和动物之间的分类关系提供了有价值的线索。关于叶鳍鱼类大脑组织的进一步数据是至关重要的，因为叶鳍鱼类的一些早期成员产生了第一批陆地脊椎动物。活的叶鳍鱼类包括腔棘鱼和肺鱼；大多数是相对罕见的，几乎都是受威胁的；而且腔棘鱼是不可能按需获得的。因此，比较腔棘鱼大脑的实验研究是不可行的。目前的观点认为肺鱼的大脑是高度异常的，但申请人在非洲肺鱼中产生了一个新的前脑组织模型。这个模型表明，肺鱼的前脑组织与陆地脊椎动物的前脑组织远比人们认识到的要相似得多。他现在提议通过使用生物示踪剂来揭示肺鱼大脑的某些特征，来测试这个模型中固有的三个假设。他将把这些特征与两栖动物（最早的陆地脊椎动物）的特征进行比较。如果他的假设成立，那么肺鱼是与所有陆地脊椎动物祖先关系最密切的活叶鳍鱼类，它们的前脑组织可以用来推断肺鱼和陆地脊椎动物共同祖先的前脑组织。这项工作将为脊椎动物神经系统如何服务于新的行为和变化机制提供见解。该项目的数据有望揭示中枢神经系统的强大适应策略，可以追溯到最早的陆地脊椎动物。这些数据还将为神经生物学家、进化生物学家、古生物学家和一般脊椎动物生物学家提供有关第一批陆地动物的宝贵新信息。

The applicant proposes to perform experiments on the brains of lungfishes that will determine if they are the closest living relative to the ancestor of all land vertebrates, including humans. Brain organization, particularly the organization of the forebrain, provides valuable clues to the biology of an animal and to taxonomic relationships among animals. Further data on brain organization in lobe-finned fishes is critical, as some early member of the lobe-finned fishes gave rise to the first land vertebrates. Living lobe-finned fishes include the coelacanth and the lungfishes; most are relatively rare, almost all are threatened; and coelacanths are impossible to obtain on demand. Experimental studies comparing coelacanth brains are therefore not feasible. Current opinion holds that lungfish brains are highly aberrant, but the applicant has generated a new model of forebrain organization in the African lungfish. This model suggests that forebrain organization in lungfishes is far more similar to that in land vertebrates than has been recognized. He now proposes to test three hypotheses inherent in this model by using biological tracers to reveal certain features of lungfish brains. He will compare these features with those in amphibians (the first land vertebrates). If his hypotheses are valid, then lungfishes are the living lobe-finned fishes most closely related to the ancestor of all land vertebrates, and their forebrain organization can be used to infer forebrain organization in the common ancestor of lungfishes and land vertebrates. This work will provide insights into how vertebrate nervous systems have subserved new mechanisms of behavior and change. Data from the project are expected to reveal a robust adaptive strategy for the central nervous system, extending back to the earliest land vertebrates. The data will also provide valuable new information about the first land animals for neurobiologists, evolutionary biologists, paleontologists and general vertebrate biologists.