The Superior Frontal Longitudinal Tract: Connection between the Dorsal Premotor and the Dorsolateral Prefrontal Cortices

The structural connection between the dorsal premotor (PMd) and the lateral prefrontal cortices (DLPFC) has been revealed, in a few studies, as the frontal longitudinal system (FLS). This study conducted a tractography analysis and a limited, postmortem, white-fiber dissection to investigate the superior FLS tract (SFLT) and analyze both its symmetry and termination point patterns. An analysis of spatial location, termination points, laterality, and correlation with the subjects9 gender or handedness was performed. SFLT was constructed in 100% of right and 88% of the left hemispheres. The tracts exhibited variable patterns in different subjects in their posterior terminations. Additionally, the SFLT was found to possess a complex spatial relationship with the adjacent bundles. The SFLT was revealed successfully in two right hemispheres, where the posterior terminations were found to originate in the PMd, and its posterior terminations being totally separate from the superior longitudinal fasciculus.