Altered structural brain connectivity involving the dorsal and ventral language pathways in 16p11.2 deletion syndrome

Abstract

Copy number variants at the chromosomal locus 16p11.2 contribute to neurodevelopmental disorders such as autism spectrum disorders, epilepsy, schizophrenia, and language and articulation disorders. Here, we provide detailed findings on the disrupted structural brain connectivity in 16p11.2 deletion syndrome (patients: N = 21, age range: 8-16 years; typically developing (TD) controls: 18, 9-16 years) using structural and diffusion MRI. We performed global short-, middle-, long-range, and interhemispheric connectivity analysis in the whole brain using gyral topology-based cortical parcellation. Using region of interest analysis, we studied bilateral dorsal (3 segments of arcuate fasciculus (AF)) and ventral (inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF), uncinate fasciculus (UF)) language pathways. Our results showed significantly increased axial (AD) and radial (RD) diffusivities in bilateral anterior AF, decreased volume for left long AF, increased mean diffusivity (MD) and RD for right long AF, and increased AD for bilateral UF in the 16p11.2 deletion group in the absence of significant abnormalities in the whole-brain gyral and interhemispheric connectivity. The selective involvement of the language networks may aid in understanding effects of altered white matter connectivity on neurodevelopmental outcomes in 16p11.2 deletion.

Keywords: 16p11.2 deletion; Autism; Brain networks; Diffusion tensor imaging; Language pathways.

Fig. 1

Connectivity analysis based on gyral topology. This figure is partially reproduced from Im et al. (2014)

Fig. 2

ROI-based segmentation of the dorsal and ventral language pathways. Left: Dorsal language pathways: Anterior segment, long segment, posterior segment of the arcuate fasciculus. Right: Ventral language pathways: Inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, uncinate fasciculus