Article

Two distinct forms of functional lateralization in the human brain

Section on Cognitive Neuropsychology, Laboratory of Brain and Cognition, and Scientific and Statistical Computing Core, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 08/2013; 110(36). DOI: 10.1073/pnas.1302581110
Source: PubMed

ABSTRACT

The hemispheric lateralization of certain faculties in the human brain has long been held to be beneficial for functioning. However, quantitative relationships between the degree of lateralization in particular brain regions and the level of functioning have yet to be established. Here we demonstrate that two distinct forms of functional lateralization are present in the left vs. the right cerebral hemisphere, with the left hemisphere showing a preference to interact more exclusively with itself, particularly for cortical regions involved in language and fine motor coordination. In contrast, right-hemisphere cortical regions involved in visuospatial and attentional processing interact in a more integrative fashion with both hemispheres. The degree of lateralization present in these distinct systems selectively predicted behavioral measures of verbal and visuospatial ability, providing direct evidence that lateralization is associated with enhanced cognitive ability.

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Available from: Stephen J. Gotts
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    • "Lateralization in both structure and function has been explained by an evolutionary advantage ensuring more efficient transcortical integration of information and avoiding cognitive processing redundancy [Hugdahl, 2011]. In fact, leftward lateralization of functional circuits subserving motor control is more beneficial for motor performance in typical children [Barber et al., 2012] and the degree of lateralization in visuospatial and languagerelated networks predicts cognitive performance [Gotts et al., 2013; Mellet et al., 2014]. Furthermore, atypical, right-or bi-hemispheric lateralization is more common in clinical populations with language deficits such as dyslexia [Johnson et al., 2013], stuttering [Foundas et al., 2001], specific language impairments [de Guibert et al., 2011], schizophrenia [Chance et al., 2008; Oertel-Kn€ ochel and Linden, 2011], and autism [Lindell and Hudry, 2013]. "
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    ABSTRACT: In humans, both language and fine motor skills are associated with left-hemisphere specialization, whereas visuospatial skills are associated with right-hemisphere specialization. Individuals with autism spectrum conditions (ASC) show a profile of deficits and strengths that involves these lateralized cognitive functions. Here we test the hypothesis that regions implicated in these functions are atypically rightward lateralized in individuals with ASC and, that such atypicality is associated with functional performance. Participants included 67 male, right-handed adults with ASC and 69 age- and IQ-matched neurotypical males. We assessed group differences in structural asymmetries in cortical regions of interest with voxel-based analysis of grey matter volumes, followed by correlational analyses with measures of language, motor and visuospatial skills. We found stronger rightward lateralization within the inferior parietal lobule and reduced leftward lateralization extending along the auditory cortex comprising the planum temporale, Heschl's gyrus, posterior supramarginal gyrus, and parietal operculum, which was more pronounced in ASC individuals with delayed language onset compared to those without. Planned correlational analyses showed that for individuals with ASC, reduced leftward asymmetry in the auditory region was associated with more childhood social reciprocity difficulties. We conclude that atypical cerebral structural asymmetry is a potential candidate neurophenotype of ASC. Hum Brain Mapp, 2015. © 2015 Wiley Periodicals, Inc.
    Full-text · Article · Oct 2015 · Human Brain Mapping
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    • "In older children and in adults, the degree of lateralization might be related to some measures of cognitive abilities (e.g. Gotts et al., 2013): for example, the most important deficits in academic abilities assessed in 11-year olds were found in individuals with equal motor skills in the two hands (Cheyne, Roberts, Crow, Leask, & Garcia-Finana, 2010). Moreover, left-handedness may facilitate the performance of cognitive tasks requiring greater engagement of right-hemisphere resources, such as visuospatial tasks (e.g. "

    Full-text · Dataset · Apr 2015
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    • "In older children and in adults, the degree of lateralization might be related to some measures of cognitive abilities (e.g. Gotts et al., 2013): for example, the most important deficits in academic abilities assessed in 11-year olds were found in individuals with equal motor skills in the two hands (Cheyne, Roberts, Crow, Leask, & Garcia-Finana, 2010). Moreover, left-handedness may facilitate the performance of cognitive tasks requiring greater engagement of right-hemisphere resources, such as visuospatial tasks (e.g. "
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    ABSTRACT: Manual asymmetries emerge very early in development and several researchers have reported a significant right-hand bias in toddlers although this bias fluctuates depending on the nature of the activity being performed. However, little is known about the further development of asymmetries in preschoolers. In this study, patterns of hand preference were assessed in 50 children aged 3-5 years for different activities, including reaching movements, pointing gestures and symbolic gestures. Contrary to what has been reported in children before 3 years of age, we did not observe any difference in the mean handedness indices obtained in each task. Moreover, the asymmetry of reaching was found to correlate with that of pointing gestures, but not with that of symbolic gestures. In relation to the results reported in infants and adults, this study may help deciphering the mechanisms controlling the development of handedness by providing measures of manual asymmetries in an age range that has been so far rather neglected.
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