No evidence for differences in contrast of the grey-white matter boundary in Autism Spectrum Disorders: An open replication

Abstract

The contrast of the interface between the neocortical grey matter and the white matter is emerging as an important neuroimaging phenotype for several brain disorders. To date, a single in vivo study has analysed the cortical grey-to-white matter percent contrast (GWPC) on Magnetic Resonance Imaging (MRI), and has shown a significant decrease of this contrast in several areas in individuals with Autism Spectrum Disorder (ASD) . Our goal was to replicate this study across a larger cohort, using the multicenter data from the Autism Brain Imaging Data Exchange 1 and 2 gathering data from 2,148 subjects. Multiple linear regression was used to study the effect of the diagnosis of ASD on the GWPC. Contrary to the first study, we found a statistically significant increase of GWPC among individuals with ASD in left auditory and bilateral visual sensory areas, as well as in the left primary motor cortex. These results were still statistically significant after inclusion of cortical thickness as covariate. There are numerous reports of sensory-motor atypicalities in patients with ASD, which may be the reason for the differences in GWPC that we observed. Further investigation could help us determine the potential role of a defect or a delay in intra-cortical myelination of sensory-motor regions in ASD. Code: https://github.com/neuroanatomy/GWPC .

Altered gray-white matter boundary in toddlers at risk for autism relates to later diagnosis of Autism Spectrum Disorder.

“…Some of our results were consistent in location and in direction with previous literature, e.g. increased GWC in bilateral occipital gyri was previously described by Fouquet et al in adults with ASD (26). This result suggests that increased GWC in the visual cortex remains higher across lifespan in individuals with ASD compared to TD.…”

“…Such "theory of mind" de cits have been highlighted as a feature of ASD for decades (53) and there is growing evidence supporting the presence of alterations in the DMN and more speci cally precuneus in ASD (54). Increased mean GWC values in primary cortices such as the occipital gyri (visual) and precentral gyrus (motor) are consistent with results on GWC in adults with ASD reported by Fouquet et al (26). It is also consistent with previous reports of disruption of primary motor area organization in children with ASD (55) as well as functional and structural alterations in occipital regions in the same population (56).…”

“…If our results are explained by increased neural density at the end of infancy they would thus bring further support to the hypothesis that ASD is characterized by altered neural proliferation, migration and lamination processes (27). Another explanation for decreased GM intensity would be a delay in intracortical myelination, a mechanism that was already suggested by Fouquet et al (26). Nevertheless, de cits in intracortical myelin are not as well documented in ASD and limited to animal model studies (64).…”

“…We rst sampled white matter intensity at each vertex v at 1mm beneath the white matter (WM) outer surface ( Fig.1). A distance of 1mm was chosen to facilitate comparisons with previous literature since it is the most commonly used value in GWC studies, including all existing studies exploring GWC in ASD (25) (26). Gray matter (GM) intensity value was sampled at each vertex at a distance of 30% of cortex width (de ned as the distance between outer white matter surface and pial surface) starting from the white matter outer surface.…”

Altered gray-white matter boundary in toddlers at risk for autism relates to later diagnosis of Autism Spectrum Disorder.

“…1). A distance of 1mm was chosen to facilitate comparisons with previous literature since it is the most commonly used value in GWC studies, including all existing studies exploring GWC in ASD ( 25) (26). Gray matter (GM) intensity value was sampled at each vertex at a distance of 30% of cortex width (de ned as the distance between outer white matter surface and pial surface) starting from the white matter outer surface.…”