Ocular dominance plasticity: inhibitory interactions and contrast equivalence

Brief monocular occlusion results in a transient change in ocular dominance, such that the previously patched eye makes a stronger contribution to the binocular percept after occlusion. The previously unpatched eye therefore makes a correspondingly weaker contribution to the binocular sum. To shed light on the mechanism underlying this change we investigate how the relationship between the perception of fusion, suppression, and diplopia changes after short-term monocular deprivation. Results show that fusible stimuli seen by the unpatched eye are actively suppressed as a result of patching and that this can be reversed by an interocular contrast imbalance. This suggests that dichoptic inhibition plays an important role in ocular dominance changes due to short-term occlusion, possibly by altering the contrast gain prior to binocular summation. This may help explain why this form of plasticity affects the perception of both fusible and rivalrous stimuli.