Converging structural and functional connectivity of orbitofrontal , dorsolateral prefrontal , 1 and posterior parietal cortex in the human striatum

41 Modification of spatial attention via reinforcement learning (Lee & Shomstein, 2013) requires 42 the integration of reward, attention, and executive processes. Corticostriatal pathways are an 43 ideal neural substrate for this integration because these projections exhibit a globally parallel 44 (Alexander, DeLong, & Strick, 1986), but locally overlapping (Haber, 2003), topographical 45 organization. Here we explore whether there are unique striatal regions that exhibit convergent 46 anatomical connections from orbitofrontal cortex (OFC), dorsolateral prefrontal cortex (DLPFC), 47 and posterior parietal cortex. Deterministic fiber tractography on diffusion spectrum imaging 48 data from neurologically healthy adults (N=60) was used to map frontoand parieto-striatal 49 projections. In general, projections from cortex were organized according to both a medial-lateral 50 and a rostral-caudal gradient along the striatal nuclei. Within rostral aspects of the striatum we 51 identified two bilateral convergence zones—one in the caudate nucleus and another in the 52 putamen—that consisted of voxels with unique projections from OFC, DLPFC, and parietal 53 regions. The distributed cortical connectivity of these striatal convergence zones was confirmed 54 with follow-up functional connectivity analysis from resting state fMRI data, in which a high 55 percentage of structurally connected voxels also showed significant functional connectivity. The 56 specificity of this convergent architecture to these regions of the rostral striatum was validated 57 against control analysis of connectivity within the motor putamen. These results delineate a 58 neurologically plausible network of converging corticostriatal projections that may support the 59 integration of reward, executive control, and spatial attention that occurs during spatial 60 reinforcement learning. 61 62