Psychological Correlates of Handedness and Corpus Callosum Asymmetry in Autism: The left Hemisphere Dysfunction Theory Revisited (original) (raw)
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We employed a multiple case studies approach to investigate lateralization of hand actions in typically and atypically developing children between 4 and 5 years of age. We report on a detailed set of over 1200 hand actions made by four typically developing boys and four boys with autism. Participants were assessed for unimanual hand actions to both objects and the self (self-directed behaviors). Individual and group analyses suggest that typically developing children have a right hand dominance for hand actions to objects and a left hand dominance for hand actions for self-directed behaviors, revealing a possible dissociation for functional specialization of the left and right hemispheres respectively. Children with autism demonstrated mixed-handedness for both target conditions, consistent with the hypothesis that there is reduced cerebral specialization in these children. The findings are consistent with the view that observed lateralized motor action can serve as an indirect beha...
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Journal of Autism and Developmental Disorders, 1979
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The left hemisphere is usually predominant in manual skills and language, suggesting a link between hand dominance and language. Studies of autism spectrum disorder show atypical handedness; however, few have examined language-handedness associations. Handedness, assessed by task performance, and standardized receptive and expressive language tests were completed in 110 autism spectrum disorder children (96 boys; M age ¼ 8.3 years, SD ¼ 3.8) and 45 typically developing children (37 boys; M age ¼ 8.6 years, SD ¼ 4.3), 3 to 17 years of age. The autism spectrum disorder group had a lower handedness score (was less strongly lateralized) than the control group. In the autism spectrum disorder group, there was a small effect of handedness on language; right-handers had better language than non-right-handers. Results suggest poorer language prognosis may be associated with left-or mixed-handedness in autism spectrum disorder.
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Behavior Research Methods, 2009
It contains two identical panels allowing both tactile stimulation and motor response with buttons for the fingers of each hand. The buttons have two functions. They can exert a slight tactile stimulation to a finger, and they can be pressed down by the finger to provide a motor response to the tactile stimulation allowing measuring the response time. The device was used for measuring brain asymmetry in tactile processing autistic children. The participants were given a finger tapping test followed by the procedures with unilateral and bilateral processing of tactile stimulation. All participants responded positively to the test procedure and accepted it as a kind of game. The results indicated that brains were more asymmetrical in autistic children than in controls: The right hemisphere functioned quicker than the left hemisphere.
Journal of autism and developmental disorders, 2002
Neurobiological and behavioural studies of possible left hemisphere dysfunction in autism have generated conflicting results. Left hemisphere dysfunction may manifest in autism only in tasks that invoke executive functions. Moreover, left hemisphere dysfunction may underpin autism but not Asperger's disorder. We thus aimed to systematically investigate reports of anomalous lateralization in individuals with high-functioning autism and Asperger's disorder. Two of the tasks were sensitive to executive dysfunction: a serial choice reaction-time task and a Posner-type paradigm; the remaining tasks instead investigated aspects of perceptual lateralisation. Compared with age- and IQ-matched controls, the autism group displayed deficiencies in right hemispace (and by implication, left hemisphere) performance on both executive function tasks; however, this group demonstrated normal lateralization effects on the nonexecutive, visual-perceptual tasks. In contrast, the Asperger's d...
Brain asymmetries in autism and developmental language disorder: a nested whole-brain analysis
Brain, 2004
We report a whole-brain MRI morphometric survey of asymmetry in children with high-functioning autism and with developmental language disorder (DLD). Subjects included 46 boys of normal intelligence aged 5.7-11.3 years (16 autistic, 15 DLD, 15 controls). Imaging analysis included grey-white segmentation and cortical parcellation. Asymmetry was assessed at a series of nested levels. We found that asymmetries were masked with larger units of analysis but progressively more apparent with smaller units, and that within the cerebral cortex the differences were greatest in higher-order association cortex. The larger units of analysis, including the cerebral hemispheres, the major grey and white matter structures and the cortical lobes, showed no asymmetries in autism or DLD and few asymmetries in controls. However, at the level of cortical parcellation units, autism and DLD showed more asymmetry than controls. They had a greater aggregate volume of significantly asymmetrical cortical parcellation units (leftward plus rightward), as well as a substantially larger aggregate volume of rightasymmetrical cortex in DLD and autism than in controls; this rightward bias was more pronounced in autism than in DLD. DLD, but not autism, showed a small but significant loss of leftward asymmetry compared with controls. Right : left ratios were reversed, autism and DLD having twice as much right-as left-asymmetrical cortex, while the reverse was found in the control sample. Asymmetry differences between groups were most significant in the higher-order association areas. Autism and DLD were much more similar to each other in patterns of asymmetry throughout the cerebral cortex than either was to controls; this similarity suggests systematic and related alterations rather than random neural systems alterations. We review these findings in relation to previously reported volumetric features in these two samples of brains, including increased total brain and white matter volumes and lack of increase in the size of the corpus callosum. Larger brain volume has previously been associated with increased lateralization. The sizeable right-asymmetry increase reported here may be a consequence of early abnormal brain growth trajectories in these disorders, while higher-order association areas may be most vulnerable to connectivity abnormalities associated with white matter increases.
Abnormal EEG lateralization in boys with autism
Clinical …, 2007
Objective: Functional brain abnormalities associated with autism in 3-8-year-old boys were studied with EEG recorded under controlled experimental condition of sustained visual attention and behavioral stillness. Methods: EEG was recorded in two independent samples of boys with autism (BWA) from Moscow (N = 21) and Gothenburg (N = 23) and a corresponding number of age-matched typically developing boys (TDB). EEG spectral power (SP) and SP interhemispheric asymmetry within delta, theta and alpha bands were analyzed. Results: BWA comprised a non-homogeneous group in relation to theta and alpha SP. When four outliers were excluded the only between-group difference in absolute SP was a higher amount of prefrontal delta in BWA. BWA of both samples demonstrated atypical leftward broadband EEG asymmetry with a maximum effect over the mid-temporal regions. Concurrently, the normal leftward asymmetry of mu rhythm was absent in BWA. Conclusions: The abnormal broadband EEG asymmetry in autism may point to a diminished capacity of right temporal cortex to generate EEG rhythms. The concurrent lack of normal leftward asymmetry of mu rhythm suggests that abnormalities in EEG lateralization in autism may be regionally/functionally specific. Significance: The data provide evidence for abnormal functional brain lateralization in autism.
BackgroundLeft-right asymmetry is an important organizing feature of the healthy brain. Various studies have reported altered structural brain asymmetry in autism spectrum disorder (ASD). However, findings have been inconsistent, likely due to limited sample sizes and low statistical power.MethodsWe investigated 1,774 subjects with ASD and 1,809 controls, from 54 datasets, for differences in the asymmetry of thickness and surface area of 34 cerebral cortical regions. We also examined global hemispheric measures of cortical thickness and area asymmetry, and volumetric asymmetries of subcortical structures. Data were obtained via the ASD Working Group of the ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) consortium. T1-weighted MRI data were processed with a single protocol using FreeSurfer and the Desikan-Killiany atlas.ResultsASD was significantly associated with reduced leftward asymmetry of total hemispheric average cortical thickness, compared to controls. Eight r...