Psychological Correlates of Handedness and Corpus Callosum Asymmetry in Autism: The left Hemisphere Dysfunction Theory Revisited

Abstract

Rightward cerebral lateralization has been suggested to be involved in the neuropathology of autism spectrum conditions. We investigated functional and neuroanatomical asymmetry, in terms of handedness and corpus callosum measurements in male adolescents with autism, their unaffected siblings and controls, and their associations with executive dysfunction and symptom severity. Adolescents with autism did not differ from controls in functional asymmetry, but neuroanatomically showed the expected pattern of stronger rightward lateralization in the posterior and anterior midbody based on their hand-preference. Measures of symptom severity were related to rightward asymmetry in three subregions (splenium, posterior midbody and rostral body). We found the opposite pattern for the isthmus and rostrum with better cognitive and less severe clinical scores associated with rightward lateralization.

Developmental neurotoxicity of inhaled ambient ultrafine particle air pollution: Parallels with neuropathological and behavioral features of autism and other neurodevelopmental disorders

“…The consequences of such hypomyelination and reduced CC include under-connectivity of the two hemispheres, and increased localized connectivity. Both correlate with social and language deficits and altered hand preference/usage in ASD [105-109], an inter-hemispherically-based behavior. The particular thinning of the genu of the CC in ASD is notable, given its importance to frontal cortical connectivity, and it has been seen in conjunction with increased brain size and complexity of gyrification [110].…”

Sex chromosome trisomies are not associated with atypical lateralisation for language

“…The most documented risk is for autism 24 . With relevance to the present study, theories have linked the communication difficulties in autism with atypical lateralisation 25 and left hemisphere dysfunction 26 . In addition, the 47,XXX and 47,XXY karyotypes have been explored as genetic models for schizophrenia 5 , although an increased risk for schizophrenia is not well established 27 .…”

Other Biological Aspects of the Broad Autism Phenotype

“…Another investigation by Floris et al (2013) looked at asymmetry in the brains of 40 adolescent males with ASD, 40 of their unaffected biological siblings, and 40 neurotypical control participants. Floris et al (2013) were particularly interested in the corpus callosum, due to previous research which had reported reductions in the size of the corpus callosum among people with ASD.…”

“…Floris et al (2013) were particularly interested in the corpus callosum, due to previous research which had reported reductions in the size of the corpus callosum among people with ASD. In this study, participants with ASD manifested stronger lateralization toward the right hemisphere (RH) of the brain in the posterior and anterior midbody sections of the corpus callosum.…”

“…However, the researchers did not obtain significant differences between the sibling group and the control group. As a result, they determined that "cerebral lateralization does not appear to be a marker of familial risk for" ASD (Floris et al, 2013(Floris et al, , p. 1768.…”