Representational drift gates critical-period plasticity in mouse visual cortex.

Brief monocular deprivation during a developmentally critical period, but not thereafter, shifts cortical responses toward the non-deprived eye. The characteristics of neural circuitry that permit this experience-dependent plasticity are poorly understood. Here, we performed repeated calcium imaging at cellular resolution to track the tuning properties of populations of excitatory layer 2/3 neurons in the visual cortex of juvenile mice during the critical period, adult mice after the critical period, and adult nogo-66 receptor (ngr1) mutant mice that retain critical-period plasticity. The instability of tuning for populations of neurons, termed "representational drift," was significantly greater during the critical period than in adulthood. Adult ngr1 mutant mice displayed representational drift similar to that of juvenile mice. We propose that representational drift adapts the tuning of populations of neurons to recent experience during the critical period.