Comparative connectomics: Studying the ‘why’ of human brain wiring and its shared and unique variation in relationship to human cognitive abilities

COEX 

Brains come in various shapes and sizes. Nature shows many small-brained species as well as endowed big-brained primate species like humans and chimpanzees with a proportionally large cerebral cortex. The field of 'comparative connectomics' studies commonalities in principles of neural wiring that apply across species, combined with how variations in connectivity between species may form the basis of species-specific brain function and behavior. In this talk, I will discuss both the technical challenges and opportunities of cross-species connectomics. I will start by discussing the methodology and technical details of comparing connectome maps across species. I will focus on the 'how to' and provide an overview of the challenges, technical details, and the importance of the availability of homologous brain atlases and their use in network reconstruction. In the second part, I will discuss examples of the application of these methods. I will discuss a comparison of global white matter connectivity across primate species with a 350-fold range of brain volume and the effect of allometric scaling of brains on network modularity, connectivity, and features of integration and communication. I will further link this work to the evolution of (human) cognition. For chimpanzee-human comparisons, I will discuss the notion of cognitive networks consistent across the two species, together with subtle adaptations of connectome architecture to higher-order cognitive networks (such as the default mode network) in humans, compared to a fine-tuning of the connectome network to visual and spatial working memory functions in chimpanzees.