The “smellscape” of mother's breast: Effects of odor masking and selective unmasking on neonatal arousal, oral, and visual responses

Abstract

Lactating women emit odor cues that release activity in newborns. Such cues may be carried in various substrates, including milk or areolar secretions. The present study aimed to examine the responses of infants facing their mother's breast and to sort out the source(s) of active volatile compounds emitted by the lactating breast. Infants (aged 3-4 days) were presented their mother's breast in two consecutive trials of 90 s each: a scentless condition (breast entirely covered with a transparent film) paired with one of four odorous conditions (fully exposed breast: n ¼ 15; nipple only exposed: 15; areola only exposed: 13; and milk exposed: 12). The infants were more orally activated when facing any of the odorous breast conditions than when facing the scentless breast. They cried earlier and longer, and opened their eyes less, when facing the scentless breast. Nipple, Areola, and Milk odors appeared to be equivalent to the whole breast odor in stimulating oral activity and in delaying crying onset. This study shows that volatile compounds originating in areolar secretions or milk release mouthing, stimulate eye opening, and delay and reduce crying in newborns.

The neurobiology of mammalian parenting and the biosocial context of human caregiving

“…In non-human primates, as well as in humans, olfactory and tactile cues serve a key role in the formation of attachment, may function as "hidden regulators" of maternal care (Hofer, 1987(Hofer, , 1995, and initiate a cascade that lead to the supremacy of social gaze reciprocity. For instance, Doucet et al (2007) found that among 3-4 day-old infants odor from breast led to greater infant social gaze and less crying, and 4-month old infants looked longer at faces when exposed to their mother's odor (Durand et al, 2013), suggesting that olfactory cues direct and provide an underlying support to the infant's social gaze behavior. In a decade-long study, we provided full maternal-infant bodily contact in a Kangaroo Care position (a position that integrates touch, odor, proprioception, vision, and audition) to premature neonates who were deprived of full maternal contact and found profound effects of early contact on the development of maternal-infant bonding, gaze synchrony, social outcomes and stress management until ten years of age ).…”

Family Scents: Developmental Changes in the Perception of Kin Body Odor?

“…This maternal odor appears to guide infants toward the breast and to have a calming effect (Schaal et al, 1980;Doucet et al, 2007). In older children, a preference for maternal odor is present (e.g., Montagner, 1974), and the comforting effect of parental odors is reported by some children (Ferdenzi et al, 2008).…”

Eye-Catching Odors: Olfaction Elicits Sustained Gazing to Faces and Eyes in 4-Month-Old Infants

“…The latter studies have found that olfaction promotes a range of early regulatory functions. Specifically, odors can modulate infants' arousal states [5]–[6], delay, reduce, or terminate distress and attenuate its physiological correlates [7]–[8], elicit directional head or body movements [5], [9]–[11], stimulate breathing and oral-lingual actions [12]–[14], control ingestive behavior [15]–[16], and initiate the affective tagging of objects/contexts to be approached, avoided, or ignored [17]. In addition, when newborns are exposed to their mother's breast odor, they display longer episodes of eye opening as compared to the same situation with no odor [8].…”

“…The result of such exposures is that infants experience temporally and spatially distributed touches, smells, tastes, faces, and voices that give rise to representations of specific people. For example, the nursing-related eye-opening behavior noted in newborns [8] increases over the first weeks [60], so that nursing creates privileged periods during which infants concomitantly perceive, among other stimuli, their mothers' odor and face. Given that odors can rapidly gain affective meaning by association with nurturance [11], [20], specific olfactory experience can be associated with specific visual experience.…”