Compartmentation and Connectivity of the Thalamus: fMRI "Resting State" and DWI Examinations

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The human thalamus in terms of its internal parcellation, its connectivity patterns, the functioning of its circuitry, and its relationship to the cerebral cortex, still partly constitutes a terra incognita. Almost all information processing in cortex strongly depends on the thalamic interactions. Therefore, the knowledge of thalamic connections and interconnections is important to understand cortical functions. Although changes in the thalamus play a prominent role in the functionally defined pathophysiology of psychiatric and neurodegenerative diseases, its internal structures are largely identified and delineated based on structural cytoarchitectonic postmortem atlases, which are used for localization of neuro- or radiosurgical interventions. As such, there is an urgent need to understand the functional and structural subdivisions of the thalamus in vivo and provide a valid map for scientific and clinical studies. The objective of our study is to examine the subdivisions of the thalamus and determine its cortical connectivity pattern by the use of resting state fMRI (rsfMRI) and diffusion weighted imaging (DWI). First, we want to provide an in vivo segmentation of the human thalamus, which can be used for the analysis and interpretation of imaging findings in the clinical neurosciences. Secondly, this compartmentation will be analyzed in respect to its connectivity with cortical structures by means of correlation analysis and fiber tracking (FT). In addition, specific hemispheric and gender differences will be characterized in terms of the ensuing segmentations. Finally, in a third step, the functional and structural segmentation of the thalamus will be compared and related to the existing anatomical atlases. Overall, we hope that this project will enhance our understanding of the role of the thalamus in concert with the sensory and cognitive functions of the brain.