Abstract View

ORIENTATION DISCRIMINATION IN VISUAL CORTEX AND THE STATISTICS OF NATURAL STIMULI. V.Dragoi*; M.Sur Brain & Cognitive Sci, MIT, Cambridge, MA, USA A key issue in the function of the visual cortex is whether its properties are adapted to the statistics of natural scenes. How these statistics are influenced by eye movements during vision is not well understood. We analyzed the eye movements of three rhesus monkeys freely viewing natural scenes and found a significant anisotropy in the stimulus statistics at the center of gaze. We found that fixation to an image patch is more likely to be followed by a saccade to a nearby patch of similar orientation structure or by a saccade to a more distant patch of largely dissimilar orientation structure. Dynamic changes in the orientation tuning of primary visual cortex (V1) neurons can enable the visual system to take advantage of these statistics. We recorded from awake monkey V1 neurons and found that brief adaptation to either nearby or orthogonal orientations can increase the dynamic range of single neurons near their peak orientation, by altering the slope of the orientation tuning curve. This would improve orientation discrimination performance following nearby or orthogonal adaptation, as is indeed observed psychophysically. Support Contributed By: McDonnell-Pew (VD) and NIH (MS) Citation: V. Dragoi, M. Sur. ORIENTATION DISCRIMINATION IN VISUAL CORTEX AND THE STATISTICS OF NATURAL STIMULI. Program No. 439.12. 2003 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2003. Online.