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Diffusion-weighted MRI (DTI) – Anatomical Connectivity

Contact: Dr. med. Dr. rer. pol. Svenja Caspers

The brain is composed of two main components: the cortical brain regions which contain neurons which take up and process information, and the fibre tracts which originate from neurons and provide the connections between individual brain regions. Studies on anatomical connectivity deal, among others, with these fibre tracts. The functional relevance of a specific connection can only be revealed by means of mathematical models based on functional MRI data.

The fibre tracts of the brain, and thus, information about anatomical connectivity in vivo become visible by means of diffusion-weighted MRI (DTI). By reference to the main diffusion direction of water molecules, the main course of fibre tracts can be indirectly investigated. To model the uncertainty related to the course of the fibre tract inherent in DTI data, we use the method of probabilistic tractography. Thus, the most probable course of a fibre tract within the white matter of the brain is calculated which can be visualized in three-dimensional space (“virtual brain", Collaboration (JARA) with the group „Virtual Reality“ of the RWTH Aachen University).


Predominantly, anatomically as well as functionally defined networks are investigated. Like for functionally defined networks activations from fMRI studies can be taken as seed and target regions for subsequent tractography, seed and target regions for pure anatomical studies are based on probabilistic atlases of the brain, such as the Jülich-Düsseldorf cytoarchitektonic atlas (INM-1). New evaluation algorithms are developed to quantify connection strengths between different cortical brain regions in order to enable a predication about the possible existence of the respective connection. A special focus is put on the investigation of connectivity of association cortices in the brain which are connected with numerous other cortical brain regions sinde they integrate different pieces of information to an overall impression.