The comparison of anatomical and functional parcellations in the connectivity results among individuals with Attention Deficit and Hyperactivity Disorder

The complex organization of the human cerebral cortex has been studied extensively by incorporating the parcellation techniques as it makes the scientific findings difficult to interpret. Additionally, deciding the criteria of this subdivison become more important in the functional brain imaging studies. In this study, the effect of parcellation methods on functional connectivity results were examined by using alternative parcellation methods in ADHD sample. The present study investigates the differences of ADHD and control groups, which is expected to provide significant findings in neuroimaging, by using a brain atlas based on anatomical boundaries and data-driven brain parcels obtained by decomposition of functional units. By using 1,5T-MRI-scanner, resting state fMRI data were obtained from 18 healty controls and 21 individuals with ADHD before and after stimulant medication. The node-based functional connectivity analyses were conducted using both atlas-based and data-driven parcels. Findings have shown that atlas-based parcels reveal rich group differences, while data-driven parcels are localized in certain networks. In the atlas-based functional connectivity analysis, involvement of more networks and the predominance of inter-network connectivity has shown. Also, results of the data-driven functional connectivity analysis showed more compact and prioritized intra-network connectivity changes. Lastly, the data-driven parcels showed better intra-network connectivity differences in the attention networks, which differ significantly between the ADHD and control groups, whereas atlas-based parcels showed better inter-network connectivity differences. Key Words: Functional Connectivity, Node Based Connectivity Analysis, ADHD, fMRI, Independent Component Analysis