In addition to recapitulating the molecular signature of hippocampal neurogenesis, we were able to capture the development of functional attributes in our neuronal population of interest. Previous work on hippocampal neurogenesis has demonstrated the importance of NMDAR-mediated activity in the integration and survival of DG granule neurons during a critical period following neuronal birth, indicating that the survival of new neurons and the resulting neural circuits are regulated in an input-dependent, cell-specific manner that enables them to play a critical role in learning and memory (Tashiro et al., 2006). Here we show that hESC-derived hippocampal granule neurons formed neuronal networks with a greater component of NMDAR-mediated neuronal activity at the early stage of differentiation, exhibiting greater inhibition of neuronal activity by APV, an antagonist of NMDARs. Conversely, these neural networks demonstrated a higher level of AMPA-receptor-mediated activity at the later stage, as indicated by incomplete inhibition of neuronal activity by CNQX, an antagonist of AMPA receptors, at the 3-week time point and complete inhibition of activities at the 6-week time point. Finally, previous studies have demonstrated that maturation of new
