Neuron
Volume 75, Issue 6, 20 September 2012, Pages 981-991
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Case Study
Unreliable Evoked Responses in Autism

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Summary

Autism has been described as a disorder of general neural processing, but the particular processing characteristics that might be abnormal in autism have mostly remained obscure. Here, we present evidence of one such characteristic: poor evoked response reliability. We compared cortical response amplitude and reliability (consistency across trials) in visual, auditory, and somatosensory cortices of high-functioning individuals with autism and controls. Mean response amplitudes were statistically indistinguishable across groups, yet trial-by-trial response reliability was significantly weaker in autism, yielding smaller signal-to-noise ratios in all sensory systems. Response reliability differences were evident only in evoked cortical responses and not in ongoing resting-state activity. These findings reveal that abnormally unreliable cortical responses, even to elementary nonsocial sensory stimuli, may represent a fundamental physiological alteration of neural processing in autism. The results motivate a critical expansion of autism research to determine whether (and how) basic neural processing properties such as reliability, plasticity, and adaptation/habituation are altered in autism.

Highlights

► Poor response reliability was evident across multiple sensory systems in autism ► Larger variability was unique to evoked responses, not evident in ongoing activity ► Larger variability was specific to sensory areas and not shared across entire cortex ► Unreliable responses to basic stimuli that have little apparent social value

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