Spine dynamics of PSD-95-deficient neurons in the visual cortex link silent synapses to structural cortical plasticity

Significance During critical periods, restricted time windows in early brain development, cortical neural circuits get refined in an experience-dependent manner. Postsynaptic density protein-95 (PSD-95)-dependent maturation of silent glutamatergic synapses onto principal neurons is required for the termination of the critical period for ocular dominance plasticity (ODP) in the primary visual cortex (V1) of mice. Using chronic in vivo two-photon imaging of dendritic spine dynamics in V1 of awake mice, here we show that adult PSD-95-deficient neurons display increased spine elimination after a brief monocular deprivation, a structural hallmark of juvenile ODP. Thus, adult PSD-95-deficient neurons display both functional and structural hallmarks of critical period plasticity so that PSD-95-dependent silent synapse maturation and stabilization is correlated with critical period closure.