Collaborative Research: Origin and Evolutionary Divergence of the Pancrustacean Brain

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It is still unknown when brains first appeared during the early history of life. The ways in which major brain parts that are structurally distinctive have changed over evolutionary time are also poorly understood. These knowledge gaps are partly due to the fact that fossil brains are rare and have been difficult to study. This project features scientists from three collaborating laboratories who will pool their resources to identify a set of invertebrate brain centers that mediate learning and memory. Structural and functional similarities and differences among these areas will be established across modern insect and crustacean species. The major question this research is answering is whether these brain centers share common genetic and computational attributes due to the brain?s fundamental organization being inherited by the descendants from a common ancestor; or, because brains that have arisen independently in different invertebrate groups are not able to perform certain functions unless brain areas that give them these same abilities have also arisen independently. These questions will be answered by precisely measuring the brain structures in fossilized invertebrate animals and comparing their basic arrangements with modern counterparts. The broader impact of this research will be to identify invertebrate proxies of the learning-and-memory brain centers found in vertebrate animals alive today, including humans. Identification of such proxies will inform us about how brains have evolved, and will contribute to a broader understanding of how memory centers are organized. The results will impact theories of, and research on, neural networks and artificial intelligence, and at the same time the scientists carrying out this research will develop novel strategies for identifying genealogical correspondence of brain structures across a very broad range of species. Brains analyzed for this research will be digitally reconstructed in 3D and uploaded to an open-source database for education and research purposes. The research will also provide advanced neuroscience structural analysis and genomics training to students from diverse backgrounds.The neuronal organization and circuit properties of insect mushroom bodies are well known, as are their functional properties for learning and memory. While the existence of mushroom-body-like centers exist across arthropods, it is not known whether these phenotypically or genotypically correspond to the centers in insects. The planned research will identify mushroom body-like centers across a broad range of species, analyze their discrete neural arrangements, circuit organization, and molecular attributes. These comparisons will identify the species within and outside Arthropoda that possess functional and morphological correspondences in these structures. Transcriptomics will address whether phenotypically-corresponding centers share common genomic attributes, and whether there are unique genetic networks that define arthropod mushroom bodies or whether these networks differentiate mushroom bodies in different groups of arthropods such as in insects and crustaceans. The identification of broad phenotypic and genotypic homology of these centers across a broad phyletic spectrum would suggest an ancient origin of these learning and memory centers. Equally intriguing would be results suggesting convergent evolution of learning and memory centers across taxa.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.