Early-life maternal care is required for the typical development of calming responses to back stroking

In many mammals, early interactions between caregivers and offspring involve rich physical contact during which offspring typically remain calm near the caregiver. Such contact is thought to support emotional regulation during infancy, but how prior experience shapes these mechanisms remains unclear. Here, we show that back stroking induces a calming response in human infants and mouse pups, with reduced movement. In mouse pups, back stroking further reduces heart rate, facilitates sleep onset, and attenuates stress-induced corticosterone elevations. These sleep-promoting and stress-buffering effects are absent in artificially reared pups deprived of postnatal maternal care, suggesting that early experience tunes the calming response to stroking. Transcriptomic analysis reveals reduced hypothalamic expression of the calcium channel subunit gene Cacna1b in artificially reared pups, and knockdown of hypothalamic Cacna1b in maternally reared pups abolishes stroking-induced calming. Thus, early-life maternal care and associated physical contact may shape hypothalamic circuits supporting behavioral and physiological regulation.