CREB1 and infection: We delivered LV-synapsin-shRNA (2 μl) into the bilateral DG of mice by microinjection, and 7 days later, we infused LV-VP16-CREB-GFP or 8-OH-DPAT (10−5 M, 2 μl) into the DG and measured the expression of synapsin in the hippocampus at d 21, and performed behavioral tests at d 28 after LV-VP16-CREB-GFP infection or 8-OH-DPAT microinjection.