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Asmaa Bakroon, Priyanka Roy, Vasudevan Lakshminarayanan; Directions discrimination in adolescents with autism spectrum disorders (ASD). Invest. Ophthalmol. Vis. Sci. 2018;59(9):1286. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To test whether adults with ASD are deficits at self-heading judgments. We measured visual navigation detection of optic flow motion across different paradigms: speeds, number of dots and luminance
14 individuals with high-functioning autism (HFA), and 14 matched-age and gender typical development control group (TD) (age:16-40 years, 5 females and 9 males each group) participated in this study. Series of optic-flow (OF) motion tasks that simulate radial motion as observer translated perpendicular to fronto-parallel plane were conducted to detect direction of heading. Two tasks were used: OF measured threshold of eccentricity of direction of heading (EDH), and OF measured contrast sensitivity (CS). The stimuli consisted of random dots that ran from the peripheral to one meeting point that was randomized to the right/left of a center fixation point. The number of dots (15 or 80 dots) and the speed of dots (10 cpd, 4 cpd) were tested. The stimuli duration was 300ms, followed by 500 ms interval time. Two down one up adaptive staircase method was used. Stimuli were displayed on a Macintosh laptop monitor attached with an optical tunnel to eliminate visual field distraction and to simulate optic flow illusion. Participants sat at the end of the visual tunnel and fixated at the fixation point. Responses were collected as soon as the dots disappeared using (2AFC). In CS task, eccentricity angle was fixed above threshold and only contrast threshold was measured
for EHD task, HFA group showed significant high threshold in determining direction of heading compared to TD. Specifically, at lower number of dotes and slow speed (F (1,26) = 4.63, p = 0.41, Mean= .2278), compared to higher number of dots and faster speed (F (1,26) = 4.63, p = 0.41, Mean= .1860). In CS task the HFA exhibited significantly low contrast sensitivity when number of dots was 15 (U= 44, p= .013).Threshold at 80 dots/ speed =4 dps showed no group difference (U= 57, p= .062) comparing to 80dots/10 dpc (U= 43, p= .012) indicative of intact parvocellular P-pathway in HFA. No difference was found between groups in response time at all different parameter, neither a preferred direction of heading (right or left)
Results suggested impairment of motion detectors within the middle temporal area, MT/V5 and/ or abnormal neural brain noise that possibly reduce connectivity between motion detectors in ASD
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
CS with OF
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