Optogenetic silencing of immature and mature neurons in dentate gyrus to assess their roles in memory discriminations

Discriminating similar memories and events depends on the dentate gyrus region of the hippocampus. This region is also distinctive because neurogenesis continues in adulthood. Whether both mature and immature granule cells play a role in memory discrimination, and whether the roles are distinct is actively investigated. Here we demonstrate that manipulating either mature or immature granule cells can impair discrimination of similar active place avoidance memories, but the manipulations have different effects. We also observe that prior experience modulates which memories are compromised by inactivation of immature neurons. These data demonstrate the importance of the dentate gyrus network of cells for memory discrimination.