Computational neuroanatomy of human stratum proprium of interparietal sulcus

• Published in: bioRxiv
• Main Authors: Uesaki, Maiko, Takemura, Hiromasa, Ashida, Hiroshi
• Format: Paper
• Language: English
• Published: Cold Spring Harbor Cold Spring Harbor Laboratory Press 22.04.2017; Cold Spring Harbor Laboratory
• Edition: 1.1
• Subjects: Anatomy; Brain; Brain architecture; Brain mapping; Computational neuroscience; Cortex (parietal); Functional magnetic resonance imaging; Intraparietal sulcus; Neuroscience; Parietal lobe; Substantia alba; optic flow; fMRI; stratum proprium of interparietal sulcus; visuo-vestibular integration; tractography; diffusion-weighted MRI
• ISSN: 2692-8205; 2692-8205
• DOI: 10.1101/126961

Recent advances in diffusion-weighted MRI (dMRI) and tractography have enabled identification of major long-range white matter tracts in the human brain. Yet, our understanding of shorter tracts, such as those within the parietal lobe, remains limited. Over a century ago, a tract connecting the superior and inferior parts of the parietal cortex was identified in a post-mortem study: Stratum proprium of interparietal sulcus (SPIS; Sachs, 1892). The tract has since been replicated in another fibre dissection study (Vergani et al. 2014), however, it has not been fully investigated in the living human brain and its anatomical properties are yet to be described in detail. We used dMRI and tractography to identify and characterise SPIS in vivo, and explored its spatial proximity to the cortical areas associated with optic-flow processing using fMRI. SPIS was identified bilaterally in all subjects, and its anatomical position and trajectory are consistent with previous post-mortem studies. Subsequent evaluation of the tractography results using linear fascicle evaluation and virtual lesion analysis yielded strong statistical evidence for SPIS. We also found that SPIS endpoints are adjacent to the optic-flow selective areas. In sum, we show that SPIS is a short-range tract connecting the superior and inferior parts of the parietal cortex, wrapping around the intraparietal sulcus, and that it may be a crucial anatomy underlying optic-flow processing. In vivo identification and characterisation of SPIS will facilitate further research on SPIS in relation to cortical functions, their development, and diseases that affect them.