|The field of systems neuroscience is currently undergoing a major paradigm shift. Theories in which the brain is understood as a simple accumulation of specialized components are being replaced by approaches which describe the nervous system as a complex network of many interacting processors. Our lab contributes to these new approaches by addressing structure - function relationships in complex neural networks. In particular, we investigate the layout and global organization of connections in the mammalian cerebral cortex, which is responsible for the impressive, diverse and adaptive functions of the mammalian brain.
Organization of complex brain networks
Our main effort is devoted to investigating the fundamental principles of the organization of complex brain networks using theoretical analyses. We collaborate closely with neuroanatomists who study fiber connections among different brain regions. We have developed new computational approaches for the global analysis of these very many projections in the mammalian cortex. Such analyses have revealed surprisingly regular cortical projection patterns, as well as a highly modular organization of structural connections and functional neural interactions. In addition, our modeling studies investigate how the specific neural topology arises during brain development, and how the structural features contribute to the efficient and robust functioning of the brain. This research focus is linked to network studies carried out at the Institute of Theoretical Physics (Prof. Bornholdt, Prof. Pawelzik).
Functional contributions of specialized components in brain networks
Our theoretical studies are complemented by experimental investigations that characterize the functional contributions and interactions of specialized components in brain networks, based on performance changes after brain lesions. This research particularly focuses on the brain network for spatial attention, which is distributed over several cortical and subcortical stations and is known for dynamical adaptation phenomena. These phenomena include ‘paradoxical’ lesion effects, in which some aspects of behavior surprisingly improve after lesions or impairment of neural components. We have produced such effects experimentally in healthy human subjects, using the ‘virtual lesion’ technique of transcranial magnetic stimulation (TMS). In collaboration with Prof. Fahle of the Institute of Human Neurobiology, we also use TMS to probe the adaptive organization of the human visual cortex. In addition, we have developed a game-theoretical analysis approach for identifying the causal functional contributions of brain regions from multiple-lesion experiments. These approaches illuminate the complex network function of the brain and provide the basis for new therapeutic approaches in the treatment of patients after brain injuries.