Abstract
Background: Atypical sensory processing is a common clinical observation in autism spectrum disorder (ASD). Neural hyperexcitability has been suggested as the cause for sensory hypersensitivity, a frequently reported clinical observation in ASD. We examined visual evoked responses to parametric increases in stimulus contrast in order to model neural responsivity of sensory systems in ASD. Methods: Thirteen high-functioning individuals with ASD and 12 typically developing (TD) individuals completed a steady-state visual evoked potential study. Stimuli were vertical circular gratings oscillating at 3.76 Hz at varying contrasts (5, 10, 20,..., 90 % contrast, 10 levels). The average spectral power at the stimulus oscillation frequency was calculated for each contrast level. Results: The magnitude of evoked sensory responses increased at a significantly greater rate and resulted in disproportionately elevated activation with higher contrasts in the ASD group. Approximately 45 % of ASD participants had rates of response increases greater than any TD participant. This alteration was highly associated with parental reports of these participants' sensory difficulties. Conclusions: Greater increases in visual responses over contrast manipulation suggest heightened excitability in the sensory cortex in ASD participants. Heightened neural excitability was observed in a substantial portion but not all of the ASD participants. This pattern suggests that individuals with higher excitability may constitute a neurobiologically distinct subgroup requiring individualized treatment interventions.
Original language | English (US) |
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Article number | 29 |
Journal | Journal of neurodevelopmental disorders |
Volume | 8 |
Issue number | 1 |
DOIs | |
State | Published - Aug 8 2016 |
Keywords
- Autism
- Contrast sensitivity
- Heterogeneity
- Individual differences
- Sensory hypersensitivity
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Pathology and Forensic Medicine
- Clinical Neurology
- Cognitive Neuroscience