Molecular determinants of brain size and cognitive performance

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Higher organism rely on their cognitive abilities to compete for resources such as food, territories and mates: brain function is thus directly linked with fitness. There seems to be a link between brain size and cognitive performance at least in humans, since microcephaly usually goes along with cognitive disabilities. Development of the brain is sensitive to the environment, with stress during early life negatively affecting brain development, functions and cognition. Here we aim to decipher the transcriptome and co-expression network signatures that determine brain size. Persistent effects of the nuclear accident in Chernobyl (Ukraine) provide us with the opportunity to quantify the association between environmental stress (exposure to ionizing radiation) and reduced brain size in wild vertebrate populations. The mosaic of radionuclide contamination in the area surrounding the former nuclear power plant at Chernobyl permits repeated experimental sampling within an area of similar environmental conditions but with different levels of contamination. Using the rodents Apodemus flavicolis and Myodes glareolus, we will sequence the transcriptomes of the frontal cortex, hippocampus, amygdala, and motor cortex from individuals inhabiting areas with contrasting levels of soil radionuclide contamination to determine differences in gene expression and co-expression networks (10 males and females from high, intermediate and low contamination regions; n = 480 transcriptomes in total). The very same individuals that will be used for the transcriptome study will perform standard behavioral tests, their basal metabolic rate will be measures and brain mass will be recorded, to link the transcriptome patterns to energetic costs, brain size and cognitive performance. Studying two species will allow us to determine the common molecular determinants underlying brain size and cognition. Further, considering the increasing risk of future nuclear disasters, we aim to provide important insides into health consequences of such disasters on organisms being relevant models for human biology.