Sentence comprehension in autism: thinking in pictures with decreased functional connectivity.
ABSTRACT Comprehending high-imagery sentences like The number eight when rotated 90 degrees looks like a pair of eyeglasses involves the participation and integration of several cortical regions. The linguistic content must be processed to determine what is to be mentally imaged, and then the mental image must be evaluated and related to the sentence. A theory of cortical underconnectivity in autism predicts that the interregional collaboration required between linguistic and imaginal processing in this task would be underserved in autism. This functional MRI study examined brain activation in 12 participants with autism and 13 age- and IQ-matched control participants while they processed sentences with either high- or low-imagery content. The analysis of functional connectivity among cortical regions showed that the language and spatial centres in the participants with autism were not as well synchronized as in controls. In addition to the functional connectivity differences, there was also a group difference in activation. In the processing of low-imagery sentences (e.g. Addition, subtraction and multiplication are all math skills), the use of imagery is not essential to comprehension. Nevertheless, the autism group activated parietal and occipital brain regions associated with imagery for comprehending both the low and high-imagery sentences, suggesting that they were using mental imagery in both conditions. In contrast, the control group showed imagery-related activation primarily in the high-imagery condition. The findings provide further evidence of underintegration of language and imagery in autism (and hence expand the understanding of underconnectivity) but also show that people with autism are more reliant on visualization to support language comprehension.
Full-textDOI: · Available from: Nancy Minshew, Dec 12, 2013
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ABSTRACT: In the embodied cognition framework, sensory, motor and emotional experiences are encoded along with sensorimotor cues from the context in which information was acquired. As such, representations retain an initial imprint of the manner in which information was acquired. The current study reports results indicating a lack of embodiment effects in ASD and, further, an association between embodiment differences and ASD symptomatology. The current results are consistent with an embodied account of ASD that goes beyond social experiences and could be driven by subtle deficits in sensorimotor coordination. © 2015 John Wiley & Sons Ltd.Developmental Science 01/2015; DOI:10.1111/desc.12278 · 3.89 Impact Factor
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ABSTRACT: The corpus callosum is the largest white matter structure in the brain, and it is the most consistently reported to be atypical in diffusion tensor imaging studies of autism spectrum disorder. In individuals with typical development, the corpus callosum is known to undergo a protracted development from childhood through young adulthood. However, no study has longitudinally examined the developmental trajectory of corpus callosum in autism past early childhood. The present study used a cohort sequential design over 9 years to examine age-related changes of the corpus callosum in 100 males with autism and 56 age-matched males with typical development from early childhood (when autism can first be reliably diagnosed) to mid-adulthood (after development of the corpus callosum has been completed) (3 to 41 years of age). The group with autism demonstrated a different developmental trajectory of white matter microstructure in the anterior corpus callosum's (genu and body) fractional anisotropy, which suggests atypical brain maturation in these regions in autism. When analyses were broken down by age group, atypical developmental trajectories were present only in the youngest participants (10 years of age and younger). Significant main effects for group were found in terms of decreased fractional anisotropy across all three subregions of the corpus callosum (genu, body, and splenium) and increased mean diffusivity, radial diffusivity, and axial diffusivity in the posterior corpus callosum. These longitudinal results suggest atypical early childhood development of the corpus callosum microstructure in autism that transitions into sustained group differences in adolescence and adulthood. This pattern of results provides longitudinal evidence consistent with a growing number of published studies and hypotheses regarding abnormal brain connectivity across the life span in autism.Molecular Autism 12/2015; 6(1):15. DOI:10.1186/s13229-015-0001-8 · 5.49 Impact Factor
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ABSTRACT: This study investigated electroencephalography (EEG) oscillatory activity and phase-synchronization in patients with Asperger's syndrome (AS) during visual recognition of emotional faces. In the experiment, 10 AS adults (2 females, age 19.6 ± 1.96) and 10 IQ-matched controls (3 females, age 24.4 ± 3.24) participated in tasks involving emotionality evaluation of either photograph or line-drawing faces. Emotional faces elicited comparable reaction times and evaluation scores between the two groups. In the photograph task, the AS group had no visible N400 component and lower delta/theta synchronization (350–450 ms post-stimulus onset) in the temporal and occipital–parietal regions, and much weaker phase synchronization between distant scalp regions (200–500 ms post-stimulus onset) compared with the control group. In the line-drawing task, the two groups had the same degree of delta/theta synchronization in the central and occipital–parietal regions and comparable phase synchronization between scalp regions. We conclude by hypothesizing that AS patients might have structural deficits in the amygdala and its related limbic structures, a site critical for recognition of emotional faces beyond conscious awareness, but that they preserve the intact function in the cognitive pathway to keep up comparable behavioral performances with the healthy controls through voluntary control of attention.Research in Autism Spectrum Disorders 05/2015; 13. DOI:10.1016/j.rasd.2015.01.003 · 2.96 Impact Factor