Assessing Topographic Structural Connectivity of the Human Basal Ganglia and Thalamus

Irtiza A. Gilani; Kader K. Oguz; Huseyin Boyaci; Katja Doerschner

neurons largely conform to the geometry of striatonigral projections, and the substantial primary axons of SNc project to the ipsilateral GP [Mettler 1970 ]. These connectivity pathways of SNc and SNr are illustrated in Supplemental Figure 5 and 6, respectively. It can be seen in our results that the lateral and anterior SNr project to CN and Pu. It was found by Lenglet et al. [2012] that projections from SN to GPi are mainly ventral, whereas nigrostriatal fibers project primarily to Pu medially, dorsally and ventrally. We found that the projections from SNr to GPe and GPi are primarily ventral and lateral, whereas the projections from SNc to GPe and GPi are ventral and ipsilateral. It was also demonstrated by Lenglet et al. [2012] that the most anterolateral portion of SN was strongly connected to GPi, GPe and striatum while the posterolateral portion was strongly connected to Tha. It was hypothesized in [Lenglet et al., 2012] that the medial SN, -well connected to GP but not to the striatum -comprises part of the SNc. Our results are consistent with this hypothesis since we find the medial SNc region to be strongly connected to GPe and GPi, but not well connected to Pu. SNr is one of the main projection sites of the STN [Parent and Smith, 1987] and the STN projections to SNc are additional indirect pathways through which signal from cortical regions reaches basal ganglia output structures. SNc-STN and SNr-STN pathways depicted in Figure 5 and 6, respectively, show that medial regions of SNc and SNr are strongly connected with STN. As the resolution of STN region used in our work is low, it was not possible to parcellate the author/funder. All rights reserved. No reuse allowed without permission.