Cortical Terminations of the Inferior Fronto-Occipital and Uncinate Fasciculi: Anatomical Stem-Based Virtual Dissection.
Front. Neuroanat.. 2016-05-24; 10:
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1. Front Neuroanat. 2016 May 24;10:58. doi: 10.3389/fnana.2016.00058. eCollection
Cortical Terminations of the Inferior Fronto-Occipital and Uncinate Fasciculi:
Anatomical Stem-Based Virtual Dissection.
Hau J(1), Sarubbo S(2), Perchey G(1), Crivello F(1), Zago L(1), Mellet E(1),
Jobard G(1), Joliot M(1), Mazoyer BM(1), Tzourio-Mazoyer N(1), Petit L(1).
(1)Groupe d’Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives
– UMR 5293, CNRS, CEA University of Bordeaux Bordeaux, France.
(2)Division of Neurosurgery, Department of Neurosciences, « S. Chiara »
HospitalTrento, Italy; Structural and Functional Connectivity Lab, Division of
Neurosurgery, « S. Chiara » HospitalTrento, Italy.
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.