Long-lasting memory for an odor acquired at the mother's breast.

Whether neonatal odor memory can persist into toddlerhood and influence behaviors that tap processes related to cognition (attention and exploration), motivation (choice and consumption), and emotion (hedonic processing) remains under-researched. Using a quasi-experimental longitudinal design, we examined whether an odor experienced at the mother's breast can be retained at 7 and 21 months. The prescribed prophylactic use of a camomile-scented balm defined two groups: infants exposed (CaE) or never exposed (CaNE) to camomile odor. At 7 months, exploratory responses to three similar objects differing in odor (including camomile) were analyzed. At 21 months, three tasks were used to assess toddlers' (i) facial responses; (ii) exploratory responses to three similar, but differently odorized objects; and (iii) choices between two bottles carrying different odors. CaE infants displayed preferential responses for camomile odor at both ages in every task. In contrast, CaNE infants behaved either randomly or more negatively to camomile odor. This study indicates that early odor memories acquired during breastfeeding can be reactivated and influence behavioral processes until at least toddlerhood.