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Paige M. Weinger, Vance M. Zemon, Valerie Nunez, Theresa Navalta, George Hu, Pamela Butler, James Gordon; Transient and Steady-State Short-Duration Visual Evoked Potential (VEP) Battery in Children with and without Autism Spectrum Disorder. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5737.
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A short-duration VEP battery was created to assess visual function in children with autism spectrum disorder (ASD). Traditional VEP techniques often require individuals to attend to stimuli for extended periods of time, which is often difficult for children with and without clinical disorders. The current study uses a battery of short-duration stimuli to assess early-stage visual processing in typically developing children and children with ASD. The aim is to develop VEP measures that can serve as biomarkers for subgroups of children with ASD.
Transient and steady-state VEP recordings were obtained from 12 typically developing children (7 males, ages 3-9) and 3 children with ASD (2 males, ages 8-13) using the Neucodia system (VeriSci Corp.). In short-duration runs, each stimulus condition was presented for ~2 s and the EEG was recorded synchronized to the display’s frame rate. Each condition was run 10 times. Stimulus conditions (10-deg field) included a contrast-reversing checkerboard (100% contrast) to elicit a transient VEP (tVEP) to examine multiple frequency mechanisms, a pair of radial patterns (partial-windmill and windmill-dartboard) with elements contrast-reversed at ~4 Hz (32% contrast) to elicit steady-state VEPs (ssVEP) that quantify nonlinear lateral inhibitory interactions, and a dartboard with each element contrast-reversed by a sum of high frequency sinusoids (22.8 & 24.8 Hz, 32% contrast/sinusoid) to yield an intermodulation response at 2 Hz that reflects excitatory nonlinear interactions. In addition, contrast-sweep conditions (bright or dark isolated checks) in which contrast increased in octave steps from 2-64% elicited ssVEPs at 12 Hz to assess ON/OFF pathways. Each epoch was Fourier analyzed and multivariate statistical measures were applied to determine the significance of each frequency component. Visual acuity was measured and ASD diagnoses were determined using the Autism Diagnostic Observation Schedule (ADOS).
Findings demonstrate that short-duration stimuli, in conjunction with multivariate statistical analysis of the brain’s responses, can yield sensitive and objective indices of the neural pathways under investigation. Children with ASD yielded weaker responses than typically developing children on several VEP measures, but differential effects were observed. Deficits in low contrast responses were prominent, whereas, an excitatory intermodulation response to the sum-of-two-sinusoid stimulus was relatively intact.
Short-duration epochs provide sensitive measures to quantify VEP responses in children with and without ASD. Future studies are needed to assess group differences.
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