Finding Cortical Subregions Regarding the Dorsal Language Pathway Based on the Structural Connectivity

TL;DR

This study delineates specific cortical subregions connected by the dorsal language pathway, using advanced tractography and Brainnetome atlas to enhance understanding of language-related brain circuitry.

Contribution

It identifies distinct cortical connections of fiber bundles within the dorsal language pathway, emphasizing the role of the inferior frontal junction in language circuits.

Findings

SLF-II and dorsal AF connect to rostrodorsal IPC and fusiform gyrus

SLF-III and ventral AF link to supramarginal gyrus and temporal cortex

IFJ in PFC shows strong connectivity with language-related subregions

Abstract

Although the language-related fiber pathways in the human brain, such as superior longitudinal fasciculus (SLF) and arcuate fasciculus (AF), are already well-known, understanding more sophisticated cortical regions connected by the fiber tracts is essential to scrutinizing the structural connectivity of language circuits. With the regions of interest that were selected based on the Brainnetome atlas, the fiber orientation distribution estimation method for tractography was used to produce further elaborate connectivity information. The results indicated that both fiber bundles had two distinct connections with the prefrontal corte (PFC). The SLF-II and dorsal AF are mainly connected to the rostrodorsal part of the inferior parietal cortex (IPC) and lateral part of the fusiform gyrus with the inferior frontal junction (IFJ), respectively. In contrast, the SLF-III and ventral AF were primary linked to the anterior part of the supramarginal gyrus and superior part of the temporal cortex with the inferior frontal cortex, including the Broca's area. Moreover, the IFJ in the PFC, which has rarely been emphasized as a language-related subretion, also had the strongest connectivity with the previously known language-related subregions among the PFC; consequently, we proposed that these specific regions are interconnected via the SLF and AF within the PFC, IPC, and temporal cortex as language-related circuitry.