Two opposing yet complementary ocular dominance plasticity: thalamus strengthens the weak channel while higher cortex listens to the strong signal

Abstract Monocular patching improves the non-patched eye in clinical practice, while recent laboratory evidence suggests that short-term patching strengthens the patched eye instead. The neural mechanisms underlying these opposite effects remain elusive. Using high-resolution 7T fMRI, we found two rapid and opposing mechanisms in the visual thalamus and higher visual cortex in response to monocular contrast deprivation (MCD) in human adults. Short-term MCD shifted ocular dominance of BOLD responses in favor of the deprived eye (DE) in the lateral geniculate nucleus and the ventrolateral pulvinar of the thalamus. Perceptually, DE became more sensitive in contrast detection and more dominant in binocular combination. In higher visual cortices, MCD shifted ocular dominance towards the nondeprived eye (NDE) in BOLD responses and their connectivity from V1. The 3-D shape perception was more accurate from shading cues presented to NDE compared to DE following deprivation. These findings demonstrate that a homeostatic gain modulation mechanism in the thalamus concurrently operates with a rapid Hebbian-like mechanism in the higher cortex to adaptively adjust interocular balance to abnormal binocular input.