Fig. 6.

The proportion of the synaptic current that was mediated through NMDA receptors varied as a function of age and cell type. A-C: EPSCs were recorded at +40 mV in neurons from more mature mice at P18 or P19 (gray traces, left) and less mature mice (gray traces, right) in all three types of principal cells. 100 μM APV blocked the slow component of the synaptic current (dark traces). The remaining fast EPSC was blocked by 40 μM DNQX (left) D: The fraction of peak eEPSCs that is sensitive to APV was compared between cell types and in old and young mice. The difference between T stellate and bushy cells was not statistically significant but the difference between T stellate and octopus cells was (*P < 0.05). APV-sensitive currents were larger in younger than in older mice.