Pheromone From Mother's Milk May Rapidly Promote Learning In Newborn Mammals

Newborn mammals are highly dependent on their mother's milk for survival, and they typically exhibit a defined sequence of actions when searching for milk. This searching behavior rapidly becomes increasingly directed, showing that mammalian newborns are efficient learners. Past studies of this very early learning in the European rabbit (Oryctolagus cuniculus) have shown that newborn pups engage in typical food-searching movements in response to olfactory signals that include the mammary pheromone secreted in mother's milk. The ability of newborns to rapidly improve their milk-finding skills likely involves learning that "new" odors--for example, those from the mother's abdomen, or of milk itself--are associated with food.

In the new work, the researchers investigated whether the mammary pheromone plays a role in the ability of newborns to learn to associate other odors with the availability of milk. By presenting newborns with the pheromone in combination with an otherwise "neutral" odor and subsequently testing whether the neutral odor alone would later elicit the typical food-searching behavior in the pups, the researchers were able to show that the pheromone is indeed effective at promoting the ability of the newborns to learn the significance of new odors. The researchers showed that this pheromone-induced learning is efficient from the time of birth and is capable of promoting the learning of successive different odorants presented to newborn pups.

Given its ability to promote the learning of new olfactory cues, the mammary pheromone may act as a kind of organizing signal that boosts the brain's ability to associate new odors with milk availability. This would in turn facilitate an essential skill: the ability of newborn pups to rapidly hone their suckling instincts during the first days of life.

The researchers include Gérard Coureaud, Anne-Sophie Moncomble, Delphine Montigny, Maeva Dewas, and Benoist Schaal of Centre des Sciences du Goût (CNRS/Université de Bourgogne/Inra) in Dijon, France; Guy Perrier of Etablissement National d'Enseignement Supérieur Agronomique in Dijon, France.

The Centre National de la Recherche Scientifique, Ministry of Research and Technology (Incentive Concerted Action Neuroscience), Council of Région Bourgogne, and Fyssen Foundation (Paris) gave financial support to this work.

Coureaud et al.: "A Pheromone That Rapidly Promotes Learning in the Newborn." Publishing in Current Biology 16, 1956--1961, October 10, 2006 DOI 10.1016/j.cub.2006.08.030. http://www.current-biology.com