Microstructural connectivity of the arcuate fasciculus in adolescents with high-functioning autism

School of Computing, University of Utah, Salt Lake City, UT, USA.
NeuroImage (Impact Factor: 6.36). 07/2010; 51(3):1117-25. DOI: 10.1016/j.neuroimage.2010.01.083
Source: PubMed

ABSTRACT The arcuate fasciculus is a white matter fiber bundle of great importance in language. In this study, diffusion tensor imaging (DTI) was used to infer white matter integrity in the arcuate fasciculi of a group of subjects with high-functioning autism and a control group matched for age, handedness, IQ, and head size. The arcuate fasciculus for each subject was automatically extracted from the imaging data using a new volumetric DTI segmentation algorithm. The results showed a significant increase in mean diffusivity (MD) in the autism group, due mostly to an increase in the radial diffusivity (RD). A test of the lateralization of DTI measurements showed that both MD and fractional anisotropy (FA) were less lateralized in the autism group. These results suggest that white matter microstructure in the arcuate fasciculus is affected in autism and that the language specialization apparent in the left arcuate of healthy subjects is not as evident in autism, which may be related to poorer language functioning.

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    • "In addition to face processing impairments, individuals with ASD also evidence atypical hemispheric specialization . Prior studies have revealed differences in gray [Herbert et al., 2005] and white matter [Fletcher et al., 2010] and electroencephalography (EEG) spectral power [Stroganova et al., 2007] asymmetries as well as the absence of functional lateralization for domains such as language [Cardinale, Shih, Fishman, Ford, & Muller, 2013; Eyler, Pierce, & Courchesne, 2012; Kleinhans, Muller, Cohen, & Courchesne, 2008a]. More recently, gene expression anomalies associated with cortical patterning pathways that regulate left–right asymmetry have also been found [Chow et al., 2012]. "
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    ABSTRACT: Among the many experimental findings that tend to distinguish those with and without autism spectrum disorder (ASD) are face processing deficits, reduced hemispheric specialization, and atypical neurostructural and functional connectivity. To investigate the earliest manifestations of these features, we examined lateralization of event-related gamma-band coherence to faces during the first year of life in infants at high risk for autism (HRA; defined as having an older sibling with ASD) who were compared with low-risk comparison (LRC) infants, defined as having no family history of ASD. Participants included 49 HRA and 46 LRC infants who contributed a total of 127 data sets at 6 and 12 months. Electroencephalography was recorded while infants viewed images of familiar/unfamiliar faces. Event-related gamma-band (30-50 Hz) phase coherence between anterior-posterior electrode pairs for left and right hemispheres was computed. Developmental trajectories for lateralization of intra-hemispheric coherence were significantly different in HRA and LRC infants: by 12 months, HRA infants showed significantly greater leftward lateralization compared with LRC infants who showed rightward lateralization. Preliminary results indicate that infants who later met criteria for ASD were those that showed the greatest leftward lateralization. HRA infants demonstrate an aberrant pattern of leftward lateralization of intra-hemispheric coherence by the end of the first year of life, suggesting that the network specialized for face processing may develop atypically. Further, infants with the greatest leftward asymmetry at 12 months where those that later met criteria for ASD, providing support to the growing body of evidence that atypical hemispheric specialization may be an early neurobiological marker for ASD. Autism Res 2015, ●●: ●●-●●. © 2015 International Society for Autism Research, Wiley Periodicals, Inc. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.
    Autism Research 03/2015; 8(2). DOI:10.1002/aur.1438 · 4.33 Impact Factor
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    • "Only one past study has reported a similar asymmetry reversal in ASD, with reduced FA in the left compared to right superior temporal gyrus identified (Lange et al., 2010). However, a number of other ROI based studies report that the typical lateralization pattern of TD participants is reduced in autism, specifically in the SLF and UF of the left hemisphere (Fletcher et al., 2010; Lo et al., 2010; Nagae et al., 2012). "
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    ABSTRACT: There is evidence emerging from Diffusion Tensor Imaging (DTI) research that autism spectrum disorders (ASD) are associated with greater impairment in the left hemisphere. Although this has been quantified with volumetric region of interest analyses, it has yet to be tested with white matter integrity analysis. In the present study, tract based spatial statistics was used to contrast white matter integrity of 12 participants with high-functioning autism or Aspergers syndrome (HFA/AS) with 12 typically developing individuals. Fractional Anisotropy (FA) was examined, in addition to axial, radial and mean diffusivity (AD, RD and MD). In the left hemisphere, participants with HFA/AS demonstrated significantly reduced FA in predominantly thalamic and fronto-parietal pathways and increased RD. Symmetry analyses confirmed that in the HFA/AS group, WM disturbance was significantly greater in the left compared to right hemisphere. These findings contribute to a growing body of literature suggestive of reduced FA in ASD, and provide preliminary evidence for RD impairments in the left hemisphere.
    Psychiatry Research: Neuroimaging 11/2014; 224(2). DOI:10.1016/j.pscychresns.2014.08.003 · 2.42 Impact Factor
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    • "Microstructural differences in radiation of the anterior thalamus have also been discovered in ages 12–24 months, 11, 12.8, and 39 years (Travers and Alexander 2013). Multiple studies of patients with ASD have decreased leftward lateralization in ASD in the arcuate fasciculus (Fletcher et al. 2010; Lo et al. 2011), and the uncinate fasciculus (Lo et al. 2011), and in the WM of the superior temporal gyrus (Lange et al. 2010). "
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    ABSTRACT: Research conducted by Kouijzer et al. (Appl Psychophysiol Biofeedback 38(1):17-28, 2013) compared the effects of skin conductance biofeedback and EEG-biofeedback on patients with autistic spectrum disorders to determine their relative efficacy. While they found a difference between treatment and control groups, there was no significant difference on many variables between the two treatment groups. From this, the increase in symptom alleviation from autistic spectrum disorder was attributed to non-specific factors surrounding the study. We now offer alternative explanations for their findings and propose different options for future studies. We hypothesize that the location and type of neurofeedback used adversely impacted the findings. We speculate that had they used a form of EEG-biofeedback that can combat deficiencies in connectivity and also trained the areas of the brain most affected by autism, there may have then been a significant difference between the effectiveness of EEG-biofeedback versus skin conductance biofeedback.
    Applied Psychophysiology and Biofeedback 09/2014; 40(1). DOI:10.1007/s10484-014-9255-8 · 1.13 Impact Factor
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