White matter dissection and structural connectivity of the human vertical occipital fasciculus to link vision-associated brain cortex

Keiko Kitajo,Atsushi Yamaguchi,Tatsuya Jitsuishi,Yasuo Iwadate,Tatsuya Yamamoto,Seiichiro Hirono

doi:10.1038/s41598-020-57837-7

Keiko Kitajo, Atsushi Yamaguchi + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-57837-7

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Abstract

The vertical occipital fasciculus (VOF) is an association fiber tract coursing vertically at the posterolateral corner of the brain. It is re-evaluated as a major fiber tract to link the dorsal and ventral visual stream. Although previous tractography studies showed the VOF’s cortical projections fall in the dorsal and ventral visual areas, the post-mortem dissection study for the validation remains limited. First, to validate the previous tractography data, we here performed the white matter dissection in post-mortem brains and demonstrated the VOF’s fiber bundles coursing between the V3A/B areas and the posterior fusiform gyrus. Secondly, we analyzed the VOF’s structural connectivity with diffusion tractography to link vision-associated cortical areas of the HCP MMP1.0 atlas, an updated map of the human cerebral cortex. Based on the criteria the VOF courses laterally to the inferior longitudinal fasciculus (ILF) and craniocaudally at the posterolateral corner of the brain, we reconstructed the VOF’s fiber tracts and found the widespread projections to the visual cortex. These findings could suggest a crucial role of VOF in integrating visual information to link the broad visual cortex as well as in connecting the dual visual stream.

Highlights

The vertical occipital fasciculus (VOF) is an association fiber tract coursing vertically at the posterolateral corner of the brain
Previous tractography studies showed the cortical projections of the VOF fall in the dorsal (e.g., V3A, V3B, V3d, intraparietal sulcus (IPS)-0) and the ventral visual areas as well as in the lateral occipital cortex (e.g., LO-1, LO-2)[4,7,8]
After the fiber bundles of the arcuate fasciculus (AF) appeared at the posterior end of the insula, we continued to dissect toward the postero-lateral corner of the brain at this level and found the lateral portion of VOF’s fiber bundles (Fig. 1B)

Summary

Introduction

The vertical occipital fasciculus (VOF) is an association fiber tract coursing vertically at the posterolateral corner of the brain. Previous studies have attempted to delineate cortical areas mostly with a single feature, Glasser et al.[27] defined distinct regions in the human cerebral cortex with a combination of brain-mapping techniques (cortical myelin content, cortical thickness, task-based fMRI, and resting-state fMRI) with semi-automated neuroanatomical approach. This HCP MMP1.0 (Human Connectome Project Multi-Modal Parcellation version 1.0), an updated map of the human cerebral cortex, would allow for neuroscientist in the fields of brain structure, function, and connectivity to work within a common neuroscience framework[27,28,29]. We analyzed the structural connectivity of VOF on the HCP multi-modal parcellation

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