Form and Motion Integration

Smith-Kettlewell Eye Research Institute, San Francisco CA

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Abstract

DESCRIPTION (provided by applicant): Vision in complex environments requires the ability to integrate local measurements of orientation and motion over large parts of the visual field. Moreover, this integration must be selective for stimuli that are behaviorally relevant and the visual system must be able to separate relevant stimulus information from background clutter. How this is accomplished will be studied during normal visual development and in patients with amblyopia using a combination of psychophysical, electrophysiological and functional imaging approaches. We will link the cortical sources determined by fMRI to neuronal activity recorded with high-density EEG/MEG using source localization techniques. The degree to which attention influences response sensitivity will be determined by comparing EEG responses when observers are making motion/form relevant discriminations on the test stimuli versus responses made when the observers are performing an attentionally demanding distractor task. Sensitivity to global motion and form stimuli will be determined in visually mature observers with a history of strabismus and/or amblyopia using both psychophysical and electrophysiological measures. Developmental sequences for the same stimuli will also be determined in normally developing infants and children. These tasks are likely to probe activity in extra-striate areas which may be particularly vulnerable due to extended developmental sequences.