|Reference code: ||PT/FB/BL-2004-047.05|
|Location: ||Arquivo PCA - Pasta 3/2004|
|Abnormal N1/P1 responses in children with ASD elicited by both low and high spatial frequency gratings|
|Publication year: ||2006|
It has been suggested that individuals with autistic spectrum disorder (ASD) may display abnormalities in low level visual perception.
Objectives: To investigate low level visual perception in ASD by measuring visual evoked potentials elicited by a range of spatial frequency gratings.
High density visual evoked potentials were recorded from children and adolescents (aged between 9 and 18) diagnosed with ASD, and chronological and nonverbal mental age matched typically developing controls in response to sinusoidal gratings presented at 0.5, 1, 4 and 8 cycles per degree (cpd). The stimuli, which measured 7.5º x 7.5º of visual angle, were presented foveally and were visible for 500 msec.
Analysis of EEG data at occipital leads indicated that the controls exhibited a typical N1 / P1 complex, with a clear N1 emerging between 80 and 95 msec in response to the higher frequency stimuli (4 and 8 cpd), and a P1 which increased in latency and decreased in amplitude with increasing spatial frequency. The ASD group however did not show a clear N1, and showed reduced P1 amplitude compared to the controls, at all four spatial frequencies.
These data suggest that early perceptual mechanisms, across a range of spatial frequencies, are abnormal in children with autistic spectrum disorder.
|Accessibility: ||Document exists in file|
|Secondary author(s): |
|Scope, A., Vigon, L., Buckley, D., Pascalis, O. |
|Document type: |
|Number of reproductions: |
|Milne, E., Scope, A., Vigon, L., Buckley, D., & Pascalis, O. (2006, June). Abnormal N1/P1 responses in children with ASD elicited by both low and high spatial frequency gratings. Poster presented at the International Meeting for Autism Research (IMFAR), Montreal, Canada.|
|Indexed document: ||No|
|Keywords: ||Psychophysiology / Visual perception / Autism spectrum disorder (ASD)|
Abnormal N1/P1 responses in children with ASD elicited by both low and high spatial frequency gratings