To assess whether BAF53b is sufficient for long-term memory formation in the hippocampus we reintroduced wildtype BAF53b into the dorsal hippocampus of adult Baf53b+/− het mice and wildtype littermates using adeno-associated virus (AAV). AAV expressing BAF53b (AAV-Baf53b) or the control virus (AAV-hrGFP) were surgically delivered into dorsal hippocampus 14 days prior to behavior. As shown in Figure 4, AAV-Baf53b was robustly expressed in the dorsal hippocampus and BAF53b protein levels in the Baf53b+/− het mice with AAV-Baf53b were increased to wildtype levels in CA1 (Fig 4A and 4B). Importantly all four groups of animals (WT AAV-hrGFP, Baf53b+/− AAV-hrGFP, WT AAV-Baf53b, Baf53b+/− AAV-Baf53b) showed normal motor function and anxiety (Supplemental Fig S2). All four groups of animals were tested for long-term OLM (hippocampal dependent) followed by long-term ORM (in a novel context with different objects) (hippocampal independent) (Fig4C). As shown in Figure 4D, WT AAV-hrGFP animals showed a robust preference for the displaced object indicating long-term OLM. The Baf53b+/− het mice with the control virus showed significantly impaired OLM, replicating our previous findings (Fig 2C). Wildtype animals with AAV-Baf53b also show
