photo: J.J. Soto-Angel
Decoding the gelatinous origins of brain evolution
The development of the first brains was crucial for the evolution of animals, as they made it possible to quickly process environmental stimuli and react accordingly to threats or hunting opportunities, for example. However, the evolutionary origin of brains remains a mystery. It is hypothesised that ctenophores (comb jellyfish) were one of the first animal phyla to develop an elementary brain. They have a unique neuronal integration centre, i.e. the aboral organ, which contains around 80 nerve cells in young animals. With its help, complex behaviours are controlled. The aboral organ of the ctenophores presumably developed independently of the centralized nervous systems of the bilaterians and most probably exhibits biophysical and molecular mechanisms that are characteristic of the first nervous systems.
Mnemiopsis leidy (sea walnut), a subspecies of comb jellyfish, serves as a model organism in this project. The interdisciplinary research approaches are based on the latest breakthroughs in the biology of organisms, molecular neuroscience, connectomics, inference of neuronal circuits and neurotechnology. On this foundation, a computer-assisted image of the sea walnut's neuronal network will be created, which will simultaneously be compared to its behaviour. The theoretical models will be tested using high-resolution images of the entire brain. In addition, detailed video recordings of free-living comb jellyfish will be used to develop data-based quantitative 3D models of the animals' postural and movement dynamics during hunting, propulsion and steering. The theoretical part of the project is carried out at the CIDBN, the experimental part at the Michael Sars Centre for Marine Biology at the University of Bergen, Norway.
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