Competition, inhibition, and critical periods of cortical plasticity

•Experience-dependent maturation of inhibition strengthens ipsilateral eye inputs.•Once established, inhibition is detrimental to competitive plasticity.•Disinhibition promotes synaptic depression and ocular dominance plasticity.•Feed-forward input to fast-spiking interneurons gates critical period plasticity.

Maturation of cortical inhibition just after eye opening is a necessary precedent for the emergence of competitive, experience-dependent ocular dominance plasticity in the visual cortex. What inhibition is doing in this context, though, is not clear. Here I outline new hypotheses on the roles of somatic and dendritic inhibition in the opening and closure of critical periods, and their roles in the competitive processes therein.