Language laterality in autism spectrum disorder and typical controls: A functional, volumetric, and diffusion tensor MRI study

Abstract

Language and communication deficits are among the core features of autism spectrum disorder (ASD). Reduced or reversed asymmetry of language has been found in a number of disorders, including ASD. Studies of healthy adults have found an association between language laterality and anatomical measures but this has not been systematically investigated in ASD. The goal of this study was to examine differences in gray matter volume of perisylvian language regions, connections between language regions, and language abilities in individuals with typical left lateralized language compared to those with atypical (bilateral or right) asymmetry of language functions. 14 adolescent boys with ASD and 20 typically developing adolescent boys participated, including equal numbers of left-and right-handed individuals in each group. Participants with typical left lateralized language activation had smaller frontal language region volume and higher fractional anisotropy of the arcuate fasciculus compared to the group with atypical language laterality, across both ASD and control participants. The group with typical language asymmetry included the most right-handed controls and fewest left-handers with ASD. Atypical language laterality was more prevalent in the ASD than control group. These findings support an association between laterality of language function and language region anatomy. They also suggest anatomical differences may be more associated with variation in language laterality than specifically with ASD. Language laterality therefore may provide a novel way of subdividing samples, resulting in more homogenous groups for research into genetic and neurocognitive foundations of developmental disorders.

Defining language impairments in a subgroup of children with autism spectrum disorder

“…Functional imaging studies of language processing using fMRI have found reduced activation in left inferior frontal regions and other areas in both SLI [57] and ASD [58][59][60], other atypical areas of activation (e.g., cerebellum), and in ASD, reduced functional connectivity between frontal and temporal language areas. Importantly, these atypical activation patterns vary depending on participants' handedness [61]. Taken together, the findings from the neuroimaging literature indicate that language impairments in ASD and SLI are associated with alterations in the volume of key cortical language regions, especially in the left hemisphere, and differences in activation patterns in the network of regions that support language processing.…”

“…As such, it serves as an important endophenotype for language impairment for both ASD and SLI and perhaps also for a wider range of neurodevelopment disorders, which may share some of the same genetic and biological risk markers that have been found for ASD (cf. Knaus et al [61]). …”

Handedness as a marker of cerebral lateralization in children with and without autism

“…Recent evidence suggests that ASD is likely to have an early developmental onset characterized by hypo-lateralization of brain function for expressive and receptive language processes [45] long before there is visible behavioral evidence of language impairment [46]. Motor behaviors provide one possible area of exploration for further investigation.…”

Clinical Evaluations on the Diagnosis of Autism

“…The comprehension and elaboration of language also depends, however, on auditory sensorial integration, which serves to perceive and analyze sound patterns. In the Knaus et al study, linguistic scores were correlated with grey www.intechopen.com matter deficits found in frontal and temporal lobes, autistic subjects manifesting a typical lateralization of language (Knaus et al, 2010). Temporal auditory associative areas, where mono-and multimodal auditory sensor integration crosses, are involved in the transfer of information to the internal structures of the limbic and frontoparietal integration systems.…”