Dr. Gesa Hartwigsen | Functional interactions and adaptive plasticity in language networks: Insights from combined transcranial magnetic stimulation and functional MRI

By transiently disrupting ongoing neuronal processing in the stimulated cortex, transcranial magnetic stimulation (TMS) permits causal conclusions regarding the contribution of the stimulated area to a specific brain function. In this talk, I will outline how TMS can be combined with fMRI to investigate networks for language comprehension and production. I will first introduce multifocal TMS designs that allow for the simultaneous or subsequent application of TMS over several key nodes to probe the functional relevance of these regions for a specific language function. In particular, multifocal TMS provides a means to change the functional weight within a network and investigate rapid compensation between language areas. The second part of my talk is related to the combination of plasticity-inducing TMS before a task and subsequent functional neuroimaging to investigate adaptive plasticity in language networks. I will show that a TMS-induced perturbation might suppress task-related activity not only in the stimulated area, but in a large task-specific network. Moreover, TMS can also modulate the effective connectivity within a network of interest. Finally, I will address how the upregulation of neighbouring regions or networks after a TMS-induced perturbation of one key region can contribute to a better understanding of (short-term) reorganization and plasticity in the healthy network and in patients with post-stroke aphasia.