S19- Responses of human neonates to odorants occurring in body secretions

Meeting Abstract S19 in proceedings " XXVIIth Annual Meeting of the European Chemoreception Research Organization, ECRO"International audienceThe sense of smell is known to be functional in human neonates, enabling them to detect and discriminate odorants, and to memorize and adequately respond to odour cues and signals from their environment. During the last decades, responsiveness to milk and breast odours has been of scientific interest due to their obvious ecological salience to newborns which is reflected in their positive responses to them. The more recent elucidation of odour-active compounds in milk and other bodily fluids makes it possible to not only study behavioural responses to the original odour mixtures but also to their constituents. The experiments presented here aimed to characterize the odour compositions of human colostrum and transitory milk, and neonatal responses to individually administered odorants. In view of their occurrence in body secretions, we hypothesized these odorants to elicit a positive behavioural response in the neonates.Gas chromatography-olfactometry (GC-O) was applied to distillates from colostrum and transitory milk samples to identify the odorants which are most potent to the adult nose. Further, the detection and hedonic perception of odorants, known to occur in milk and sweat, were evaluated in 3-day-old neonates, as inferred from changes in facial expressions and respiratory rate.GC-O analyses revealed that colostrum and transitory milk resemble each other in terms of their qualitative odorant compositions. The behavioural experiments indicated that neonates were more sensitive than adults to certain odorants. In contrast to our original hypothesis, however, the newborns predominantly evinced negative facial expressions, even for very low concentrations of the investigated odorants. These results will be discussed for their implications on our current understanding of neonatal odour learning and perception of odorants from body secretions