Cortical correlates of amblyopia: what information is lost and why?

Abstract

Amblyopia is a developmental disorder of vision resulting from abnormal binocular visual experience in childhood. Psychophysical studies in amblyopic humans and macaques show losses in basic spatial vision (acuity and contrast sensitivity), but in addition, there are extensive losses in higher order perceptual abilities. These deficient higher order abilities, such as global form and motion perception and perceptual organization, are not predictable from the loss in acuity. Neurophysiological studies of striate cortex in behaviorally characterized amblyopic macaques show that some aspects of amblyopia are reflected in the properties of single neurons, but that overall neural sensitivity far exceeds behavioral sensitivity. Therefore there is information available in the visual system that is not being used to guide visual performance. What information is lost and what mechanisms contribute to that loss? Our recent studies show that some answers can be found via population analyses at the level of striate and extrastriate cortex, and characterizing neural interactions under dichoptic viewing. Current thinking about the neural correlates of amblyopia will be discussed.