Social recognition memory differences between mouse strains: On the effects of social isolation, adult neurogenesis, and environmental enrichment.

Remembering conspecifics is paramount for the establishment and maintenance of groups. Here we asked whether the variability in social behavior caused by different breeding strategies affects social recognition memory (SRM). We tested the hypothesis that the inbred Swiss and the outbred C57BL/6 mice behave differently on SRM. Social memory in C57BL/6 mice endured at least 14 days, while in Swiss mice lasted 24 h but not ten days. We showed previously that an enriched environment enhanced the persistence of SRM in Swiss mice. Here we reproduced this result and added that it also increases the survival of adult-born neurons in the hippocampus. Next, we tested whether prolonged SRM observed in C57BL/6 mice could be changed by diminishing the trial duration or using an interference stimulus after learning. Neither short acquisition time nor interference during consolidation affected it. However, social isolation impaired SRM in C57BL/6 mice, similar to what was previously observed in Swiss mice. Our results demonstrate that SRM expression can vary according to the mouse strain, which shows the importance of considering this variable when choosing the most suitable model to answer specific questions about this memory system. We also demonstrate the suitability of both C57BL/6 and Swiss strains for exploring the impact of environmental conditions and adult neurogenesis on social memory.