Ethological approach to social isolation effects in behavioral studies of laboratory rodents

The aim of the present review is to discuss how housing conditions affect behavioral performance in laboratory rodents from an ethological view. Commonly used laboratory rodents such as rats and mice, are originally captured animals that largely retain species-typical natural behaviors, while have fully adapted to a laboratory setting after long-term domestication. Laboratory settings including caging and artificial group housing are a considerable ethological factor influencing rodents' behaviors in commonly employed behavioral test paradigms, including emotional and defensive behaviors, learning and memory, and attention-related behaviors. Particularly, isolation rearing, single-housed in a cage, is referred to a deprivation of social relationships with cagemates, has a substantial impact on behavioral performance in laboratory rodents. In this review, we will fully examine the importance of caging related ethological factors, e.g., social relationships and its deprivation, which are essential for unraveling the nature of housing effect in laboratory rodents. These discussions regarding the housing conditions will provide valuable information for appropriately conducting behavioral studies and interpreting data of rodents' behaviors in neuroscience.