title: Fiber tracts of the dorsal language stream in the human brain.
abstract: OBJECT The aim of this study was to examine the arcuate (AF) and superior longitudinal fasciculi (SLF), which together form the dorsal language stream, using fiber dissection and diffusion imaging techniques in the human brain. METHODS Twenty-five formalin-fixed brains (50 hemispheres) and 3 adult cadaveric heads, prepared according to the Klingler method, were examined by the fiber dissection technique. The authors' findings were supported with MR tractography provided by the Human Connectome Project, WU-Minn Consortium. The frequencies of gyral distributions were calculated in segments of the AF and SLF in the cadaveric specimens. RESULTS The AF has ventral and dorsal segments, and the SLF has 3 segments: SLF I (dorsal pathway), II (middle pathway), and III (ventral pathway). The AF ventral segment connects the middle (88%; all percentages represent the area of the named structure that is connected to the tract) and posterior (100%) parts of the superior temporal gyri and the middle part (92%) of the middle temporal gyrus to the posterior part of the inferior frontal gyrus (96% in pars opercularis, 40% in pars triangularis) and the ventral premotor cortex (84%) by passing deep to the lower part of the supramarginal gyrus (100%). The AF dorsal segment connects the posterior part of the middle (100%) and inferior temporal gyri (76%) to the posterior part of the inferior frontal gyrus (96% in pars opercularis), ventral premotor cortex (72%), and posterior part of the middle frontal gyrus (56%) by passing deep to the lower part of the angular gyrus (100%). CONCLUSIONS This study depicts the distinct subdivision of the AF and SLF, based on cadaveric fiber dissection and diffusion imaging techniques, to clarify the complicated language processing pathways.
authors.affiliation: Departments of 1 Neurological Surgery and.
authors.forename: Kaan
authors.initials: K
authors.lastname: Yagmurlu
authors.affiliation: Radiology, University of Florida, Gainesville, Florida; and.
authors.forename: Erik H
authors.initials: EH
authors.lastname: Middlebrooks
authors.affiliation: Department of Neurosurgery, Cerrahpasa Medical Faculty, Istanbul University, Turkey.
authors.forename: Necmettin
authors.initials: N
authors.lastname: Tanriover
authors.affiliation: Departments of 1 Neurological Surgery and.
authors.forename: Albert L
authors.initials: AL
authors.lastname: Rhoton
mesh_terms: D000328:Adult; D001111:Arcuate Nucleus of Hypothalamus / Q000033:anatomy & histology* / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000502:physiology*; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D021621:Imaging, Three-Dimensional; D007802:Language; D009412:Nerve Fibers / Q000502:physiology* / Q000648:ultrastructure*; D009434:Neural Pathways / Q000033:anatomy & histology* / Q000502:physiology*
keywords: AF = arcuate fasciculus; BA = Brodmann area; DTI = diffusion tensor imaging; IFOF = inferior frontooccipital fasciculus; ILF = inferior longitudinal fasciculus; MLF = middle longitudinal fasciculus; ROI = regions of interest; SLF = superior longitudinal fasciculus; SMA = supplementary motor area; UF= uncinate fasciculus; anatomy; arcuate fasciculus; brain; fMRI = functional MRI; fiber dissection; fiber tracts; language processing; superior longitudinal fasciculus