Funded Grants

Function, dysfunction and repair of language networks

One of the most devastating conditions after stroke is a disturbance in language function, called aphasia. The degree of recovery from aphasia represents a crucial determinant for social and vocational rehabilitation. Here, I put forward the hypothesis that understanding the organization of language networks in the healthy brain is mandatory for understanding the mechanisms underlying reorganization of language functions after focal brain damage in patients with aphasia. Identifying these mechanisms of brain repair, in turn, is essential for developing novel strategies of language rehabilitation on a neuroscience basis.

Accordingly, my research program is divided into three parts. The first part is concerned with mapping the functional neuroanatomy of language networks in the healthy brain using a combined approach of functional and structural neuroimaging and brain stimulation techniques. Based on the assumption that cognitive functions are instantiated through the coherent and timely interaction of anatomically connected brain regions, I am particularly interested in the (causal) functional interactions between cortical brain regions and the underlying white matter fiber tracts. Predictions made by these networks will be probed by employing temporary deactivation techniques. This will allow to test the effects of a focal lesion onto the network and to identify neural mechanisms of short-term reorganization, mimicking acute reorganization in stroke.

Building upon this, the second part is dedicated to stroke patients with aphasia. The dynamics of language reorganization within the networks previously characterized will be tracked from acute to chronic stroke. Importantly, changes in connectivity between network constituents over time are assumed to reflect reorganization within the networks. I expect to identify prototypical patterns of reorganization depending on the lesion location. I am in particular interested in mapping the acute phase after stroke by using haemodynamic methods (i.e., functional MRI) in combination with methods independent of haemodynamic factors (i.e., EEG). This should help to shed more light on network pathologies especially in the acute phase of stroke. Information from the early phase will be used to predict language outcome and to identify neurobiological determinants of recovery. The final part aims at transferring these findings to language rehabilitation. The impact of stimulating crucial network constituents concurrently with behavioral training on language recovery will be investigated in subacute and chronic stroke patients. Importantly, the stimulation site is guided by the findings gained from studies in healthy subjects and patients.

In sum, my research program aims to bridge the gap between basic and clinically-relevant cognitive neurosciences. The findings are expected to provide an essential contribution to re-considering language as the function of large-scale brain networks. This new understanding of normal language and aphasia, in turn, will provide the basis for the development of effective, neurophysiologically-driven approaches to aphasia treatment.