Physiology and Plasticity

Every day, thousands of new dentate granule cells (DGCs) are born in the subgranular zone (SGZ) of the dentate gyrus (DG), wherein a niche of neuronal precursors undergoes continuous division and differentiation throughout mammalian life. Yet, only a fraction of these cells will ultimately survive and mature to become functional members of the DG neuronal population. Newborn DGCs form early excitatory GABAergic and later excitatory glutamatergic synapses as they join the functional architecture of the DG. In addition, newborn cells are more plastic than mature ones, likely helping younger cells to form connections and contribute meaningfully to hippocampal function. What processes regulate the fate of newborn DGCs, how do they integrate into the existing neuronal circuitry of the hippocampus, and what are the physiological/behavioral roles of DG plasticity? Here we review the current evidence, largely based on studies in rodents and nonhuman primates.