Do NMDA receptor kinetics regulate the end of critical periods of plasticity?

Increasing NR2A subunit expression and the associated shortening of the NMDA-EPSC are thought to underlie the loss of diverse types of sensory cortical plasticity. Lu and colleagues (Lu et al., 2001 [this issue of Neuron]) now report that mice lacking the NR2A subunit display normal duration of critical periods of barrel cortex plasticity. Shortening of the NMDA-EPSC is therefore not responsible for the end of these critical periods.