title: Cortical Terminations of the Inferior Fronto-Occipital and Uncinate Fasciculi: Anatomical Stem-Based Virtual Dissection.
abstract: We combined the neuroanatomists' approach of defining a fascicle as all fibers passing through its compact stem with diffusion-weighted tractography to investigate the cortical terminations of two association tracts, the inferior fronto-occipital fasciculus (IFOF) and the uncinate fasciculus (UF), which have recently been implicated in the ventral language circuitry. The aim was to provide a detailed and quantitative description of their terminations in 60 healthy subjects and to do so to apply an anatomical stem-based virtual dissection, mimicking classical post-mortem dissection, to extract with minimal a priori the IFOF and UF from tractography datasets. In both tracts, we consistently observed more extensive termination territories than their conventional definitions, within the middle and superior frontal, superior parietal and angular gyri for the IFOF and the middle frontal gyrus and superior, middle and inferior temporal gyri beyond the temporal pole for the UF. We revealed new insights regarding the internal organization of these tracts by investigating for the first time the frequency, distribution and hemispheric asymmetry of their terminations. Interestingly, we observed a dissociation between the lateral right-lateralized and medial left-lateralized fronto-occipital branches of the IFOF. In the UF, we observed a rightward lateralization of the orbito-frontal and temporal branches. We revealed a more detailed map of the terminations of these fiber pathways that will enable greater specificity for correlating with diseased populations and other behavioral measures. The limitations of the diffusion tensor model in this study are also discussed. We conclude that anatomical stem-based virtual dissection with diffusion tractography is a fruitful method for studying the structural anatomy of the human white matter pathways.
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives - UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
authors.forename: Janice
authors.initials: J
authors.lastname: Hau
authors.affiliation: Division of Neurosurgery, Department of Neurosciences, "S. Chiara" HospitalTrento, Italy; Structural and Functional Connectivity Lab, Division of Neurosurgery, "S. Chiara" HospitalTrento, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Sarubbo
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives - UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
authors.forename: Guy
authors.initials: G
authors.lastname: Perchey
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives - UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Crivello
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives - UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
authors.forename: Laure
authors.initials: L
authors.lastname: Zago
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives - UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mellet
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives - UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
authors.forename: Gaël
authors.initials: G
authors.lastname: Jobard
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives - UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Joliot
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives - UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
authors.forename: Bernard M
authors.initials: BM
authors.lastname: Mazoyer
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives - UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Tzourio-Mazoyer
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives - UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Petit
keywords: diffusion tensor imaging; human brain anatomy; inferior fronto-occipital fasciculus; tractography; uncinate fasciculus; white matter