Decreased Interhemispheric Functional Connectivity in Autism

Department of Neuroradiology, University of Utah, 1A71 School of Medicine, Salt Lake City, UT 84132, USA.
Cerebral Cortex (Impact Factor: 8.67). 10/2010; 21(5):1134-46. DOI: 10.1093/cercor/bhq190
Source: PubMed


The cortical underconnectivity theory asserts that reduced long-range functional connectivity might contribute to a neural mechanism for autism. We examined resting-state blood oxygen level-dependent interhemispheric correlation in 53 males with high-functioning autism and 39 typically developing males from late childhood through early adulthood. By constructing spatial maps of correlation between homologous voxels in each hemisphere, we found significantly reduced interhemispheric correlation specific to regions with functional relevance to autism: sensorimotor cortex, anterior insula, fusiform gyrus, superior temporal gyrus, and superior parietal lobule. Observed interhemispheric connectivity differences were better explained by diagnosis of autism than by potentially confounding neuropsychological metrics of language, IQ, or handedness. Although both corpus callosal volume and gray matter interhemispheric connectivity were significantly reduced in autism, no direct relationship was observed between them, suggesting that structural and functional metrics measure different aspects of interhemispheric connectivity. In the control but not the autism sample, there was decreasing interhemispheric correlation with subject age. Greater differences in interhemispheric correlation were seen for more lateral regions in the brain. These findings suggest that long-range connectivity abnormalities in autism are spatially heterogeneous and that transcallosal connectivity is decreased most in regions with functions associated with behavioral abnormalities in autism. Autism subjects continue to show developmental differences in interhemispheric connectivity into early adulthood.


Available from: Jason R. Cooperrider, May 20, 2015
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    • "VMHC is a voxelwise measurement of functional homotopy that reveals the synchrony of resting-state functional connectivity between a voxel in one hemisphere and its mirrored counterpart in the other. VMHC has been successfully used to explore the interhemispheric functional coordination in autism, schizophrenia, cocaine addiction, and other diseases [24] [25] [26] [27] [28]; however, VMHC has, to our knowledge, not been used previously to investigate interhemispheric functional coordination in tinnitus patients and to study the relationships between altered interhemispheric functional connectivity and other tinnitus characteristics such as tinnitus duration or severity. "
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    ABSTRACT: Purpose. Recent studies suggest that tinnitus may be due in part to aberrant callosal structure and interhemispheric interaction. To explore this hypothesis we use a novel method, voxel-mirrored homotopic connectivity (VMHC), to examine the resting-state interhemispheric functional connectivity and its relationships with clinical characteristics in chronic tinnitus patients. Materials and Methods. Twenty-eight chronic tinnitus patients with normal hearing thresholds and 30 age-, sex-, education-, and hearing threshold-matched healthy controls were included in this study and underwent the resting-state fMRI scanning. We computed the VMHC to analyze the interhemispheric functional coordination between homotopic points of the brain in both groups. Results. Compared to the controls, tinnitus patients showed significantly increased VMHC in the middle temporal gyrus, middle frontal gyrus, and superior occipital gyrus. In tinnitus patients, a positive correlation was found between tinnitus duration and VMHC of the uncus. Moreover, correlations between VMHC changes and tinnitus distress were observed in the transverse temporal gyrus, superior temporal pole, precentral gyrus, and calcarine cortex. Conclusions. These results show altered interhemispheric functional connectivity linked with specific tinnitus characteristics in chronic tinnitus patients, which may be implicated in the neuropathophysiology of tinnitus.
    02/2015; 2015. DOI:10.1155/2015/345647
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    • "However, several studies have reported that hemispheric activation, structure, and/or functional connectivity differ between ASD and non-autistic individuals. For instance, reduced inter-hemispheric connectivity, implying less interhemispheric synchronization, has been noted in adults (Anderson et al. 2011) and toddlers (Dinstein et al. 2011) with ASD using resting state fMRI. There have also been several reports of anatomical differences between hemispheres in individuals with ASD versus controls, including larger right parieto-occipital regions (Hier et al. 1979), and smaller left planum temporale (Rojas et al. 2002). "
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    ABSTRACT: Previous findings have shown that individuals with autism spectrum disorder (ASD) evince greater intra-individual variability (IIV) in their sensory-evoked fMRI responses compared to typical control participants. We explore the robustness of this finding with a new sample of high-functioning adults with autism. Participants were presented with visual, somatosensory and auditory stimuli in the scanner whilst they completed a one-back task. While ASD and control participants were statistically indistinguishable with respect to behavioral responses, the new ASD group exhibited greater IIV relative to controls. We also show that the IIV was equivalent across hemispheres and remained stable over the duration of the experiment. This suggests that greater cortical IIV may be a replicable characteristic of sensory systems in autism.
    Journal of Autism and Developmental Disorders 10/2014; 45(5). DOI:10.1007/s10803-014-2276-6 · 3.34 Impact Factor
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    • "The transfer of information is reduced due to less specialized autistic brain, i.e., overconnectivity between neural assemblies (Misic et al., 2014) and underconnectivity of the functional brain regions (Mostofsky and Ewen, 2011; Just et al., 2012), resulting in language impairment (Verly et al., 2013) and reduced learning rate (Schipul et al., 2012). Dinstein et al. (2011) reported weak interhemispheric neural synchronization (Anderson et al., 2011) in toddlers with autism. The disrupted neural synchronization is evident in naturally sleeping autistic toddlers, and the strength of cortical synchronization is negatively correlated in autistic subjects, whereas it is positively correlated in subjects with verbal ability. "
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    ABSTRACT: Abstract Autism spectrum disorder (ASD) is a complex neurobiological disorder characterized by neuropsychological and behavioral deficits. Cognitive impairment, lack of social skills, and stereotyped behavior are the major autistic symptoms, visible after a certain age. It is one of the fastest growing disabilities. Its current prevalence rate in the U.S. estimated by the Centers for Disease Control and Prevention is 1 in 68 births. The genetic and physiological structure of the brain is studied to determine the pathology of autism, but diagnosis of autism at an early age is challenging due to the existing phenotypic and etiological heterogeneity among ASD individuals. Volumetric and neuroimaging techniques are explored to elucidate the neuroanatomy of the ASD brain. Nuroanatomical, neurochemical, and neuroimaging biomarkers can help in the early diagnosis and treatment of ASD. This paper presents a review of the types of autism, etiologies, early detection, and treatment of ASD.
    Reviews in the neurosciences 09/2014; 25(6). DOI:10.1515/revneuro-2014-0056 · 3.33 Impact Factor
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