SI Appendix for Manuscript: Reactivation of critical period plasticity in adult auditory cortex through chemogenetic silencing of parvalbumin-positive interneurons

Sensory experience during early developmental critical periods (CPs) has profound and long-lasting effects on cortical sensory processing perduring well into adulthood. Although recent evidence has shown that reducing cortical inhibition during adulthood reinstates CP plasticity, the precise cellular mechanisms are not well understood. Here we show for the first time that the chemogenetic inactivation of parvalbumin-positive (PV+) interneurons is sufficient to reinstate CP plasticity in the adult auditory cortex. Bidirectional manipulation of PV+ cell activity affected neuronal spectral and sound intensity selectivity, and, in the case of PV+ interneuron inactivation, was mirrored by anatomical changes in PV and associated perineuronal net expression. These findings underscore the importance of sustained PV-mediated inhibitory neurotransmission throughout life and highlight the potential of chemogenetic approaches for harnessing cortical plasticity with the ultimate goal of aiding recovery from brain injury or disease.