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Impaired Feature Integration in Autism Spectrum Disorders Across Visual Hemifields

Friday, 3 May 2013: 09:00-13:00
Banquet Hall (Kursaal Centre)
I. A. Peiker1, N. David1, T. Schneider1, D. Schöttle2 and A. K. Engel1, (1)Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, (2)Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
Background: The integration of visual details into a holistic percept is essential for object recognition. As this cognitive process seems to be impaired in people with autism spectrum disorders (ASD), autism might reflect a disorder of information integration. At the neural level, disrupted communication between brain areas could account for the cognitive deficits. In fact, altered connectivity has been reported in ASD, especially for interhemispheric communication.  

Objectives: We sought to address whether connectivity is disturbed within or across cerebral hemispheres. Therefore, we employed the “slitviewing paradigm” which probes visuotemporal integration in an object identification task. A previous study using this paradigm showed lower performance of ASD individuals compared to a control group, but did not directly address altered connectivity as underlying pathology.

Methods: 20 adults with ASD and 20 control individuals matched for gender and age participated in the MEG-study. Participants viewed images of objects passing behind a vertical or horizontal slit and were asked to name the object they identified. Only fragments of the objects were visible at a given moment and thus had to be integrated over time. The horizontal slit, in contrast to its vertical counterpart, was intended to require integration over both hemispheres. MEG was recorded to investigate oscillatory neuronal activity from both hemispheres during the integration process.

Results: Behavioral data showed a significant interaction between group and the orientation of the slit. That is, participants with ASD were less accurate identifying objects presented behind a horizontal versus vertical slit, while controls did not show such a performance difference between slit-conditions. The behavioral interaction was paralleled by an interaction at the neurophysiological level. Specifically, spectral power in the gamma band (at 80 Hz) was increased in the condition with the horizontal compared to the vertical slit within the ASD-group at central sensors, while it was not statistically different within the control group. In contrast, controls showed a condition effect at occipital sensors in lower frequencies, extending from theta to lower beta bands.

Conclusions: The oscillatory activity pattern implies different underlying brain processes with respect to visual feature integration in ASD compared to controls. In favor of our hypothesis, our findings might reflect reduced communication across cerebral hemispheres. As in real-world contexts stimuli regularly appear in both hemifields this finding is strongly relevant for the understanding of visual perception in autism.

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