**The connectivity fingerprint of the human frontal cortex, subthalamic nucleus and striatum**
*Isaacs, B.R., Forstmann, B.U., Temel, Y., Keuken, M.C.*
Within the cortico-Basal Ganglia (BG)-thalamic network, the direct and indirect pathways comprise of projections from the cortex to the striatum (STR), whereas the hyper-direct pathway(s) consists of cortical projections towards the subthalamic nucleus (STN). Each pathway possess a functionally distinct role for action selection. The current study quantified and compared the structural connectivity between 17 distinct cortical areas with the STN and STR using 7 Tesla Diffusion Weighted Imaging (DWI) and resting-state functional MRI (rs-fMRI) in healthy young subjects. The selection of these cortical areas was based on a literature search focusing on animal tracer studies. The results indicate that, relative to other cortical areas, both the STN and STR showed markedly weaker connections to areas assumed to be essential for action inhibition such as the inferior frontal cortex. Additionally, the cortical connectivity fingerprint of the STN and STR indicated relatively strong connections to areas related to reward processing.
Finally, there were differences in the cortical connectivity fingerprint between the STN and STR. Overall the results indicated that the cortical-STN connections were sparser compared to the STR. There were two notable exceptions, namely for the FEF and CIN, where a higher tract strength was found for the STN. These two areas are thought to be involved in inhibitory control processes through integration of sensory information, direction of attention, and monitoring action selection.