Revisiting the human uncinate fasciculus, its subcomponents and asymmetries with stem-based tractography and microdissection validation
Brain Struct Funct. 2016-08-31; 222(4): 1645-1662
DOI: 10.1007/s00429-016-1298-6
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1. Brain Struct Funct. 2017 May;222(4):1645-1662. doi: 10.1007/s00429-016-1298-6.
Epub 2016 Aug 31.
Revisiting the human uncinate fasciculus, its subcomponents and asymmetries with
stem-based tractography and microdissection validation.
Hau J(1), Sarubbo S(2)(3), Houde JC(4), Corsini F(2)(3), Girard G(4), Deledalle
C(5), Crivello F(1), Zago L(1), Mellet E(1), Jobard G(1), Joliot M(1), Mazoyer
B(1), Tzourio-Mazoyer N(1), Descoteaux M(4), Petit L(6).
Author information:
(1)Groupe d’Imagerie Neurofonctionnelle, Institut des Maladies
Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146
rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France.
(2)Division of Neurosurgery, Department of Neurosciences, « S. Chiara » Hospital,
Trento APSS, Trento, Italy.
(3)Structural and Functional Connectivity Lab, Division of Neurosurgery, « S.
Chiara » Hospital, Trento APSS, Trento, Italy.
(4)Sherbrooke Connectivity Imaging Lab, University of Sherbrooke, Sherbrooke,
Canada.
(5)Institut de Mathématiques de Bordeaux-UMR 5251, CNRS, Talence, France.
(6)Groupe d’Imagerie Neurofonctionnelle, Institut des Maladies
Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146
rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France.
.
Despite its significant functional and clinical interest, the anatomy of the
uncinate fasciculus (UF) has received little attention. It is known as a
‘hook-shaped’ fascicle connecting the frontal and anterior temporal lobes and is
believed to consist of multiple subcomponents. However, the knowledge of its
precise connectional anatomy in humans is lacking, and its subcomponent divisions
are unclear. In the present study, we evaluate the anatomy of the UF and provide
its detailed normative description in 30 healthy subjects with advanced
particle-filtering tractography with anatomical priors and robustness to crossing
fibers with constrained spherical deconvolution. We extracted the UF by defining
its stem encompassing all streamlines that converge into a compact bundle, which
consisted not only of the classic hook-shaped fibers, but also of straight
horizontally oriented. We applied an automatic-clustering method to subdivide the
UF bundle and revealed five subcomponents in each hemisphere with distinct
connectivity profiles, including different asymmetries. A layer-by-layer
microdissection of the ventral part of the external and extreme capsules using
Klingler’s preparation also demonstrated five types of uncinate fibers that,
according to their pattern, depth, and cortical terminations, were consistent
with the diffusion-based UF subcomponents. The present results shed new light on
the UF cortical terminations and its multicomponent internal organization with
extended cortical connections within the frontal and temporal cortices. The
different lateralization patterns we report within the UF subcomponents reconcile
the conflicting asymmetry findings of the literature. Such results clarifying the
UF structural anatomy lay the groundwork for more targeted investigations of its
functional role, especially in semantic language processing.
DOI: 10.1007/s00429-016-1298-6
PMID: 27581617 [Indexed for MEDLINE]