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FRIMEDBIO-Fri prosj.st. med.,helse,biol

The origin and evolution of bilaterian brains

Alternative title: Opphav og evolusjon av hjernen hos bilaterier

Awarded: NOK 8.1 mill.

The brain, the frontal part of the central nervous system of animals, coordinates essential functions including the reception of the environment, the coordination of movements and learning and decision making. The human brain contains different parts that emerged at different times in animal evolution. Although the brain is a key-innovation in evolutionary history, its origin and the evolution of different parts of the brain has not yet been elucidated. This research project aims to solve several unanswered questions of brain evolution by studying brain development in different animals. Single-cell sequencing technologies fertilized the field of comparative studies. We analyze new single-cell sequencing data from ribbon worms, gastrotrichs, acoels. Given their large evolutionary distances we include more species and their public datasets to “bridge” the distance. Future behavioural studies in these animals will allow to learn about the capabilities of ancient brain parts. Alltogether, this will allow to better understand brain evolution including the brain of us humans. We however show that complex brains evolved multiple times in animals and the earliest brain was likely a commissural brain.

The brain, the anterior part of the central nervous system of animals, coordinates essential functions of an animal including the reception of the environment, the coordination of movements and learning and decision making. Although the brain is a key-innovation in evolutionary history, its origin and further diversification into the complex, multiple-lobed anterior nerve centralizations with millions of neurons of a broad range of animals has not been elucidated. Our knowledge of brain development and evolution is mainly based on work performed in prominent model systems including vertebrates (fish, frog and mouse) and invertebrates that are distantly-related and considered to be highly derived (Drosophila and C. elegans). The project proposed herein aims to study brain development in a variety of highly informative animal taxa, with the ultimate aim of reconstructing the history of brain diversity during animal evolution. We aim to test current hypotheses of brain evolution (‘tripartite-brain’, ‘chimeric brain’) using the comparative approach using the current phylogenetic framework. Our approach combines advanced bioinformatics, molecular methods and behavioral experiments, and will be carried out in eight representative species belonging to under-investigated animal phyla. We will describe the morphological and molecular composition of brains in these species and integrate it with novel fossil data from Chengjiang provided by our collaborator. Using this information we will be able to infer the morphology, molecular patterning and possibly the cell type composition of ancestors at six important nodes in the animal tree of life. We will also be able to comprehend when shifts in brain evolution have occurred and how these shifts have remodeled the animal body plans and ultimately their behavioral complement.

Funding scheme:

FRIMEDBIO-Fri prosj.st. med.,helse,biol

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