Adversity severity shapes caregiving predictors and neural correlates of infant social behavior

Early-life adversity presents a complex landscape of developmental outcomes, often shaped by varying levels of exposure. Animal models, standardized to set parameters while allowing subtle variations in developmental experience, provide a valuable avenue for exploration. Researchers conducted a study utilizing a graded limited bedding and nesting model, ranging from normative rearing to severe scarcity, to scrutinize the influence of resource restrictions on social behavior.

Severe scarcity led to heightened adverse maternal handling, while maintaining structured nurturing behaviors. Pups exposed to this condition were then assessed through a social approach assay, revealing that the proportion of pups approaching their mother decreased significantly. Nevertheless, the outcomes varied considerably among the scarcity litters.

Greater typical maternal pup transport was positively correlated with enhanced approach behavior, while a larger proportion of rough transport was associated with poorer approach. It is noteworthy that transport composition remained consistent across rearing conditions, yet its association with social behavior was evident. Moreover, amygdala intercalated-cell recruitment exhibited a covarying relationship with social approach under severe scarcity, even though there were minimal condition-specific differences in regional c-Fos expression.

Plasma corticosterone levels, however, varied across rearing conditions but did not show a discernible correlation with the key caregiving, behavioral, or neural measures. Notably, maternal transport and intercalated-cell recruitment were not strongly linked, indicating distinct experiential and neural correlates of the observed behavioral variations.

The findings underscore that standardizing an environmental constraint does not inevitably result in homogeneous developmental experiences or outcomes. Furthermore, they highlight that caregiving practices preserved across different rearing conditions can serve as a distinguishing factor in social outcomes observed under severe scarcity.