A Novel Neighbor Housing Environment Enhances Social Interaction and Rescues Cognitive Deficits from Social Isolation in Adolescence

Abstract

Adolescence is characterized by high levels of playful social interaction, cognitive development, and increased risk-taking behavior. Juvenile exposure to social isolation or social stress can reduce myelin content in the frontal cortex, alter neuronal excitability, and disrupt hypothalamic pituitary adrenal (HPA) axis function. As compared to group housed animals, social isolation increases anxiety-like phenotypes and reduces social and cognitive performance in adulthood. We designed a neighbor housing environment to alleviate issues related to social isolation that still allowed individual homecages. Neighbor housing consists of four standard mouse cages fused together with semi-permeable ports that allow visual, olfactory, and limited social contact between mice. Adolescent C57BL/6J males and females were group housed (4/cage), single housed (1/cage), or neighbor housed (4/complex). As adults, mice were tested for social, anxiety-like, and cognitive behaviors. Living in this neighbor environment reduced anxiety-like behavior in the social interaction task and in the light-dark task. It also rescued cognitive deficits from single housing in the novel object recognition task. These data suggest that neighbor housing may partially ameliorate the social anxiety and cognitive deficits induced by social isolation. These neighbor cage environments may serve as a conduit by which researchers can house mice in individual cages while still enabling limited social interactions to better model typical adolescent development.

Lack of social touch increases anxiety and alters social behaviors in mice

“…This increased anxiety was further supported by social dominance as measured by the tube test 10 . The most surprising finding in this study was that, in contrast to previous studies 8,9 , divided housing caused even higher anxiety levels than single housing. These results implied that sensing other social signals without direct physical interaction may produce an even more stressful environment than complete social isolation.…”

“…Unexpectedly, our experiment did not detect a significant difference between single-housed and pair-housed mice in either anxiety-or depressionlike behavior. Although it is generally believed that anxiety and depression can be induced by social isolation, this relationship has not always been consistent in mouse studies 8,9,15,16 . Failure to detect the difference might be due to the shorter isolation time or larger isolation space in our experimental designs.…”

“…Multiple social signals are exchanged during social interactions. While some social modalities, such as olfactory and auditory cues, have been studied extensively and suggested to be important in alleviating social isolation syndrome in mice 8,9 , the specific influences of social touch on animal health and physiology have rarely been addressed. In fact, during the COVID-19 pandemic, people can still exchange visual or auditory social signals by virtual meeting or phone.…”

Prolonged epigenetic and synaptic plasticity alterations following single exposure to a psychedelic in mice

“…or vehicle and immediately returned to their home cage. Preference for light or dark environment as a proxy for anxiety-like behaviors was assessed 18h after drug administration using a commercial open field in which space is equally divided into light and dark areas (25 × 12 × 20 cm each) connected through a small (5 × 5 cm) opening ( 67 ). The tracking system (Fusion v5.3; Omnitech Electronics Inc.) infers animal activity and position from interruptions to infrared beams traversing the different planes of space.…”

Stress Varies Along the Social Density Continuum

“…Another study found that developmentally isolated adult female mice take longer than socially-housed mice to learn an operant task, though after training they did not show reduced performance on a USV discrimination task (Screven and Dent, 2019). Notably, one study suggests that the effects of adolescent social isolation may be ameliorated by partial indirect social housing, holding promise for future study (Pais et al, 2019).…”