The comparative connectome

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What makes humans unique? Relative to our body size, we have the largest brain of any primate. This massive brain allows us to dominate the planet, while our closest animal cousins, the great apes, are relegated to small patches of Africa and Indonesia. However, exactly what changed in our brain when it got bigger and how this relates to our uniquely human behaviors, such as spoken language, advanced tool-making, and bipedal walking, remains a mystery. In this project, we try to solve this mystery, by comparing the architecture of our brain to that of a range of other primates.If we want to understand what makes our brain different, it is not enough to compare it to that of just one other ape or monkey. We differ in many respects from other primates and thus any differences we find might find can be related to many behaviors. If we want to understand how different behaviors are related to particular changes in our brain, we have to compare our brain to that of a range of other primates, each with different behaviors. Therefore, in this project we aim to map the connections and brain regions of a range of different primates.We will use new developments in neuroimaging to scan the brain of primates post-mortem. We will obtain the brains from animals that have lived in zoos and that have died through causes completely unrelated to our research. This will allow us to study more species than ever before without any ethical constraints. By using neuroimaging we can obtain different types of information from each brain, such as how big specific brain regions are, where they are located, and how they are connected. This project will be based at the University of Oxford's FMRIB centre. The Fellow and a post-doctoral research assistant will conduct the majority of the work, in collaboration with the MRI Physics Group at FMRIB.We will investigate differences in brains related to three types of behavior that we believe are particularly well developed in humans: language, tool use, and general decision-making.Human language has been suggested to be possible due to a series of new connections between the temporal and frontal cortex of the human brain. However, it has recently been suggested that some of these connections are already present in great apes, such as gorillas, which mean they might not be exclusively related to language. By comparing these connections between monkeys, apes, and humans we can test this idea, and see which connections are special to which group of animals.Human tool-making has been essential in our conquest of the world. It is thought that we integrate much more complex conceptual information into our tool use than other animals do. This can have happened in two ways, by the formation of a new pathway in the brain specifically for using tools or by elaborating on existing pathways for reaching and grasping in the parietal and premotor cortex of monkeys. We will compare the pathways connecting parietal and premotor cortex in humans and monkeys and see whether there is a new pathway in humans that might mediate tool behavior.The most distinctive part of our human brain is the prefrontal cortex, which is very large in the human brain and has been related to our decision-making abilities However, whether this size is the reason that our brain is capable of complex behavior or whether it is due to the extended connections with the rest of the brain that bring our frontal cortex more information than in the monkey is unknown. We can only study this by comparing both the size and the connections of the frontal cortex across species. This way, we can see whether in our brain the relationship between size and connections of the frontal cortex is as predicated based on other primates or whether there is something special about our case.Together, this work will help us understand not only what makes us different from other animals, but also what makes these animals different from one another.