Abstract
Experience-dependent neuronal plasticity is most evident during a critical period, a limited time in early life, after which neurons become less plastic. Removal of chondroitin sulfate proteoglycans (CSPGs), components of the brain extracellular matrix, reactivates neuronal plasticity in adult animals after the termination of the critical period; therefore, CSPGs long have been recognized as non-specific physical barriers that limit neuronal plasticity. In contrast, recent studies provide evidence that CSPGs may have specific effects on neuronal connectivity; a sulfation code of on chondroitin sulfate (CS) chains that is specified by specific CS sulfation modifications may encode functional information on CSPGs that regulates neuronal plasticity. During postnatal development, CSPGs form perineuronal nets around parvalbumin-expressing inhibitory interneurons, and these neurons are key players in experience-dependent plasticity. Here, we review recent studies on the roles of CSPGs in experience-dependent plasticity, focusing on the relationship between the CS sulfation code and functional maturation of inhibitory interneurons.
