Neuroanatomical differences in brain areas implicated in perceptual and other core features of autism revealed by cortical thickness analysis and voxel‐based morphometry

Abstract

Autism spectrum disorder is a complex neurodevelopmental variant thought to affect 1 in 166 [Fombonne (2003): J Autism Dev Disord 33:365-382]. Individuals with autism demonstrate atypical social interaction, communication, and repetitive behaviors, but can also present enhanced abilities, particularly in auditory and visual perception and nonverbal reasoning. Structural brain differences have been reported in autism, in terms of increased total brain volume (particularly in young children with autism), and regional gray/white matter differences in both adults and children with autism, but the reports are inconsistent [Amaral et al. (2008): Trends Neurosci 31:137-145]. These inconsistencies may be due to differences in diagnostic/inclusion criteria, and age and Intelligence Quotient of participants. Here, for the first time, we used two complementary magnetic resonance imaging techniques, cortical thickness analyses, and voxel-based morphometry (VBM), to investigate the neuroanatomical differences between a homogenous group of young adults with autism of average intelligence but delayed or atypical language development (often referred to as "high-functioning autism"), relative to a closely matched group of typically developing controls. The cortical thickness and VBM techniques both revealed regional structural brain differences (mostly in terms of gray matter increases) in brain areas implicated in social cognition, communication, and repetitive behaviors, and thus in each of the core atypical features of autism. Gray matter increases were also found in auditory and visual primary and associative perceptual areas. We interpret these results as the first structural brain correlates of atypical auditory and visual perception in autism, in support of the enhanced perceptual functioning model [Mottron et al. (2006): J Autism Dev Disord 36:27-43].

Effects of age and symptomatology on cortical thickness in autism spectrum disorders

“…Increased thickness and other structural atypicalities in the ACC were initially reported in post-mortem studies (Bailey et al, 1998;Kemper & Bauman, 1993). Previous structural MRI studies reported both decreased grey matter volume in the ACC (Abell et al, 1999;Kwon, Ow, Pedatella, Lotspeich, & Reiss, 2004;McAlonan et al, 2002), and increased thickness in this region in individuals with ASD relative to controls (Bonilha et al, 2008;Hyde et al, 2010;Schmitz et al, 2006;Toal et al, 2009), but there were no data on age-related changes in the ACC. The present study is important in its findings of developmental changes in cortical thickness in ASD in the rACC, a region central to the social cognitive functions.…”

“…Some groups have reported increased thickness or density in brain regions in groups of pre-adolescents (Bonilha et al, 2008) and adults (Hyde, Samson, Evans, & Mottron, 2010;Schmitz et al, 2006;Toal et al, 2009) with ASD relative to typically developing individuals. As these prior studies focused on samples with narrower age ranges their results reflect alterations in brain morphology during restricted periods and are not able to examine developmental changes.…”

Intrinsic gray-matter connectivity of the brain in adults with autism spectrum disorder

“…For instance, individuals with ASD may have a reduced size, but increased number, of minicolumns (8), which could underpin differences in cortical surface area (9,10). Also, individuals with ASD may have an excess number of neurons in some brain regions (11), which in turn may affect measures of cortical thickness (9,12). Therefore, different morphometric features of the cortical surface provide proxy measures of various aspects of local gray-matter architecture.…”

Morphological changes in gray matter volume correlate with catechol-O-methyl transferase gene Val158Met polymorphism in first-episode treatment-naïve patients with schizophrenia

“…However, compared with FreeSurfer, GMVs based on VBM provide more precise measures of subcortical structures such as the basal ganglia [52,53] which may be one of the important etiological locations in schizophrenia. In addition, as suggested by…”