LONG-TERM EFFECTS OF JUVENILE SOCIAL ISOLATION ON SOCIAL INTEREST IN MICE

Early social experiences are essential for healthy socio-emotional development, whereas deprivation during sensitive periods can lead to long-lasting behavioral alterations. Juvenile social isolation (jSI) in rodents, which corresponds to early adolescence in humans, is a widely used model of early-life stress and has been shown to disrupt adult social behavior. This developmental window is critical for brain maturation, as early social interactions shape neuronal circuits across multiple brain regions. However, the impact of jSI on social development and socio-cognitive functions, such as emotion recognition, remains poorly understood. Here, we investigated whether jSI affects emotion recognition and social interest for conspecific in adulthood. Male and female C57BL/6J mice were socially isolated from postnatal day 21 to 35 and then regrouped until adulthood; control mice remained group-housed (GH). Behavioral testing was conducted between P65 and P120. Emotion recognition and social interest were assessed using the emotion discrimination task (EDT), which measures the ability to differentiate between conspecifics expressing positive or negative affective states. We found that jSI did not alter the recognition of either positive or negative emotional states in conspecifics in either sex. Instead, jSI induced a sex-specific alteration in social interaction patterns, with males preferentially spending more time interacting with jSI male conspecifics compared to GH males, an effect not observed in females. These findings indicate that jSI does not impair emotion recognition per se but selectively reshapes adult social interaction preferences in a sex-dependent manner, suggesting sensitivity to cues related to the social isolation history of conspecifics.