title: Amblyopic deficits in processing structure-from-motion.
abstract: Amblyopic observers exhibit a range of low- and high-level cortical deficits, and there is strong evidence that the extrastriate cortex is selectively affected for signal/noise tasks but not for simple integration tasks. We tested amblyopic and control observers on a structure-from-motion (SFM) task involving signal integration to gauge whether extrastriate processing is compromised at a level where dorsal and ventral information is combined. SFM tasks require integration of local elements to perceive the global structure using motion-defined depth cues. Observers were monocularly presented with a 2-IFC shape discrimination task and asked to indicate whether two consecutive SFM stimuli represented the same or different depth-defined shapes. Amblyopic observers had higher depth thresholds than control observers, even after controlling for low-level differences in contrast thresholds across eyes and observers. Combined with the presence of the deficit in both the amblyopic and fellow-fixing eyes, this suggests a high-level locus for the SFM deficit.
authors.affiliation: McGill Vision Research Unit, Department of Ophthalmology, McGill University, and Royal Victoria Hospital, Montreal, Quebec, Canada. jesse.husk@mail.mcgill.ca
authors.forename: Jesse S
authors.initials: JS
authors.lastname: Husk
authors.forename: Reza
authors.initials: R
authors.lastname: Farivar
authors.forename: Robert F
authors.initials: RF
authors.lastname: Hess
mesh_terms: D000328:Adult; D000550:Amblyopia / Q000503:physiopathology*; D015858:Anisometropia / Q000503:physiopathology; D002540:Cerebral Cortex / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology; D003867:Depth Perception / Q000502:physiology; D004948:Esotropia / Q000503:physiopathology; D005099:Exotropia / Q000503:physiopathology; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D013285:Strabismus / Q000503:physiopathology; D014795:Visual Pathways / Q000502:physiology*; D055815:Young Adult