Early Visual Experience Shapes Binocularity in the Mouse Thalamocortical Pathway

Developing neural circuits are particularly vulnerable to alterations in early sensory experience. For example, monocular deprivation (MD) during a juvenile critical period leads to long-lasting changes in ocular dominance and spatial acuity in primary visual cortex. The locus of these changes has been widely considered to be cortical. However, recent evidence indicates that binocular integration may occur first in the dorsolateral geniculate nucleus of the thalamus (dLGN), leaving open the question of whether changes in early visual experience can affect binocularity in dLGN. Using in vivo two-photon Ca 2+ imaging of dLGN afferents in superficial layers of mouse visual cortex, we demonstrate that critical-period MD selectively impairs binocularity in dLGN inputs while visual acuity in this pathway remains relatively intact. Our data suggest that alterations in cortical ocular dominance following critical-period MD may partially reflect binocularity loss in dLGN neurons, whereas acuity deficits first manifest in primary visual cortex.