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Coarse to fine visual orientation processing in discrimination ta | 52155
Journal of Clinical and Experimental Ophthalmology

Journal of Clinical and Experimental Ophthalmology
Open Access

ISSN: 2155-9570

+44 1223 790975

Coarse to fine visual orientation processing in discrimination tasks


lnternational Conference on Eye Disorders and Treatment

July 13-15, 2015 Baltimore, USA

Juliana Dushanova and Dimitar Mitov

Posters-Accepted Abstracts: J Clin Exp Ophthalmol

Abstract :

Introduction: The effects of visual stimulus orientation difference on visual event-related potential components (VERP) were studied in healthy humans. Methods: Trials with an orientation difference of more than 150 (�??coarse�?�) and of less than 150 (�??fine�?� identification) were compared for two tasks: Sensory-motor (left forefinger reaction for vertical stimulus orientation gratings, right forefinger reaction for oblique or horizontal gratings) and sensory-mental (counting oblique vs. horizontal stimuli). Task difficulty increased when the orientation difference decreased from 15° to 5°. Results: We found cortical topological similarities in �??coarse�?� and �??fine�?� orientation discrimination processing. Greater VERP changes were observed within the range of 50-150 than within the range of 150-900. The amplitudes of the P2/N2 waves and the latency of the P3 wave decreased with increased task difficulty in both tasks. Task difficulty modulated the amplitude of P3 and the latency of N1/N2 waves in opposite directions for the sensory-motor and sensory-mental task respectively. Small changes in task difficulty affected attentional effort and modulated the parameters of N1/P2 waves only for the sensory-mental task. Conclusion: The VERP changes correspond to psychophysical data regarding both the selectivity of human vision orientationspecific channels and the transition between detector and computational mode of operation in orientation perception.

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