Neurobiology of Language -
New PhD: Rene Terporten
Language processing in the human brain has been frequently shown not to be solely restricted to the classical language (Broca's areas and/or Wernickes area) regions of the perisylvian cortex. Instead, a wide and distributed patchwork of other areas seems to be involved, which in turn is thought to support language processing as it is heavily shaped by context constrains. Related to this claim, it has been shown that brain areas that are generally agreed to be involved in e.g. sensory or motor processing also become active if sensory or motor content is emphasized by the processed language context. While these studies highlight where in the brain such processes might take place, it remains an open question of how and when these flexible language processes occur.
It can be argued that if flexibility in language processing is achieved by a brain language system, its underlying architecture should also organize itself dynamically and flexibly. A network theory of the language system allows for the explanation of these dynamic and flexible brain mechanisms, by means of core-periphery interactions as a function of time. A cognitive function is thus the result of a specific organization of core and periphery nodes in a brain network, at a particular moment in time. While the contribution of a core to this cognitive function might be relatively stable over time, its relationship with a periphery changes dynamically according to task demands. In that sense, a varying context might dynamically shape the periphery of a language network, while the language network's cores remain relatively stable. These dynamic network adaptations can happen very quickly and therefore a measurement with a good time resolution should be favored in order to investigate how and when these adaptations take place in the brain.
As a first step, I will use magnetoencephalography (MEG) to exploit its excellent time resolution. In an experimental session, power modulations in various oscillatory frequency bands as well as event related fields will be investigated during sentence processing, as context constrains parametrically vary. These power modulations are in turn thought to index the underlying dynamics in a recurrent language network and thereby provide a first approach in understanding how and when flexible language processing is realized by the brain. This insight will pave the way for exciting future experiments within the project. By using MEG in conjunction with magnetic resonance imaging and a focus on connectivity analyses, modulations of directionality in information flow between core language areas and its periphery will be investigated, as a function of different degrees of context constrains.