PVALB and schizophrenia: Among the neural substrates affected in schizophrenia, parvalbumin-positive interneurons (PVs), which are fast-spiking, inhibitory interneurons [31,32,33], and perineuronal nets (PNNs), which form part of the extracellular matrix (ECM) that surrounds PVs, both regulate E/I balance in the cortex [34].