Repressor Element 1-Silencing Transcription Factor (REST) regulates the expression of a wide array of neuronal genes implicated in differentiation, development and plasticity. We demonstrate the effect of REST inhibition on primary visual cortex (V1) plasticity in the adult mouse. Employing the monocular deprivation paradigm and experimentally-induced amblyopia in a RESTGTi conditional knockout (cKO) model, we studied the effects of stereotaxically delivering Cre recombinase into V1 via adeno-associated virus vectors (AAVs) on visual cortex plasticity in vivo. To this end, we recorded visual evoked potentials (VEPs) with chronic multi-electrode implants in the awake animal, vision-correlated behavior via the optomotor response (OMR) and molecular changes in ex vivo brain tissue with immunofluorescence and RT-PCR. We are currently investigating the differential involvement of astrocytes and neurons using specific viral expression promoters (GFAP, hSynI and CaMKII). Electrophysiology shows that REST cKO in the V1 of adult mice enables a shift of ocular dominance after short-term monocular deprivation and promotes vision recovery in a model of amblyopia, mirrored by a variation of OMR score. RT-PCR and immunofluorescence demonstrate a concurrent increase in the expression of plasticity-related REST target genes and marked reduction of perineuronal net density. Inhibition of REST activity in vivo can reactivate plasticity in the adult visual cortex after the end of the critical period, paving the way for new therapeutic strategies for the correction of amblyopia and synergistic enhancement of retinal prosthetic function in cases of inherited blindness.Supported by IRCCS Ospedale Policlinico San Martino 5x1000 Grant no. C814A