Olfaction scaffolds the developing human from neonate to adolescent and beyond

The impact of the olfactory sense is regularly apparent across development. The foetus is bathed in amniotic fluid that conveys the mother’s chemical ecology. Transnatal olfactory continuity between the odours of amniotic fluid and milk assists in the transition to nursing. At the same time, odours emanating from the mammary areas provoke appetitive responses in newborns. Odours experienced from the mother’s diet during breastfeeding, and from practices such as pre-mastication, may assist in the dietary transition at weaning. In parallel, infants are attracted to and recognise their mother’s odours; later, children are able to recognise other kin and peers based on their odours. Familiar odours, such as those of the mother, regulate the child’s emotions, and scaffold perception and learning through non-olfactory senses. During adolescence, individuals become more sensitive to some bodily odours, while the timing of adolescence itself has been speculated to draw from the chemical ecology of the family unit. Odours learnt early in life and within the family niche continue to influence preferences as mate choice becomes relevant. Olfaction thus appears significant in turning on, sustaining and, in cases when mother odour is altered, disturbing adaptive reciprocity between offspring and caregiver during the multiple transitions of development between birth and adolescence

Duchenne smile, emotional experience, and autonomic reactivity: A test of the facial feedback hypothesis.

This study examined the modulatory function of Duchenne and non-Duchenne smiles on subjective and autonomic components of emotion. Participants were asked to hold a pencil in their mouth to either facilitate or inhibit smiles and were not instructed to contract specific muscles. Five conditions-namely lips pressing, low-level non-Duchenne smiling, high-level non-Duchenne smiling, Duchenne smiling, and control-were produced while participants watched videoclips that were evocative of positive or negative affect. Participants who displayed Duchenne smiles reported more positive experience when pleasant scenes and humorous cartoons were presented. Furthermore, they tended to exhibit different patterns of autonomic arousal when viewing positive scenes. These results support the facial feedback hypothesis and suggest that facial feedback has more powerful effects when facial configurations represent valid analogs of basic emotional expressions

Inter-Brain Synchronization during Social Interaction

During social interaction, both participants are continuously active, each modifying their own actions in response to the continuously changing actions of the partner. This continuous mutual adaptation results in interactional synchrony to which both members contribute. Freely exchanging the role of imitator and model is a well-framed example of interactional synchrony resulting from a mutual behavioral negotiation. How the participants' brain activity underlies this process is currently a question that hyperscanning recordings allow us to explore. In particular, it remains largely unknown to what extent oscillatory synchronization could emerge between two brains during social interaction. To explore this issue, 18 participants paired as 9 dyads were recorded with dual-video and dual-EEG setups while they were engaged in spontaneous imitation of hand movements. We measured interactional synchrony and the turn-taking between model and imitator. We discovered by the use of nonlinear techniques that states of interactional synchrony correlate with the emergence of an interbrain synchronizing network in the alpha-mu band between the right centroparietal regions. These regions have been suggested to play a pivotal role in social interaction. Here, they acted symmetrically as key functional hubs in the interindividual brainweb. Additionally, neural synchronization became asymmetrical in the higher frequency bands possibly reflecting a top-down modulation of the roles of model and imitator in the ongoing interaction

The Secretion of Areolar (Montgomery's) Glands from Lactating Women Elicits Selective, Unconditional Responses in Neonates

BACKGROUND:The communicative meaning of human areolae for newborn infants was examined here in directly exposing 3-day old neonates to the secretion from the areolar glands of Montgomery donated by non related, non familiar lactating women. METHODOLOGY/PRINCIPAL FINDINGS:The effect of the areolar stimulus on the infants' behavior and autonomic nervous system was compared to that of seven reference stimuli originating either from human or non human mammalian sources, or from an arbitrarily-chosen artificial odorant. The odor of the native areolar secretion intensified more than all other stimuli the infants' inspiratory activity and appetitive oral responses. These responses appeared to develop independently from direct experience with the breast or milk. CONCLUSION/SIGNIFICANCE:Areolar secretions from lactating women are especially salient to human newborns. Volatile compounds carried in these substrates are thus in a position to play a key role in establishing behavioral and physiological processes pertaining to milk transfer and production, and, hence, to survival and to the early engagement of attachment and bonding

Dysfunction of the Mesolimbic Circuit to Food Odors in Women With Anorexia and Bulimia Nervosa: A fMRI Study

Brain reward dysfunction in eating disorders has been widely reported. However, whether the neural correlates of hedonic and motivational experiences related to food cues are differentially affected in anorexia nervosa of restrictive type (ANr), bulimia nervosa (BN), and healthy control (HC) participants remains unknown. Here, 39 women (14 ANr, 13 BN, and 12 HC) underwent fMRI while smelling food or non-food odors in hunger and satiety states during liking and wanting tasks. ANr and BN patients reported less desire to eat odor-cued food and odor-cued high energy-density food (EDF), respectively. ANr patients exhibited lower ventral tegmental area (VTA) activation than BN patients to food odors when rating their desire to eat, suggesting altered incentive salience attribution to food odors. Compared with HC participants, BN patients exhibited decreased activation of the caudate nucleus to food odors in the hunger state during the wanting task. Both patient groups also showed reduced activation of the anterior ventral pallidum and insula in response to high EDF odors in the hunger state during the wanting task. These findings indicate that brain activation within the food reward-regulating circuit differentiates the three groups. ANr patients further exhibited lower activation of the precuneus than other participants, suggesting a possible role of body image distortion in ANr. Our study highlights that food odors are relevant sensory probes to gain better insight into the dysfunction of the mesolimbic and striatal circuitry involved in food reward processing in patients with EDs

Positive relationship between odor identification and affective responses of negatively valenced odors

Hedonic ratings of odors and olfactory preferences are influenced by a number of modulating factors, such as prior experience and knowledge about an odor's identity. The present study addresses the relationship between knowledge about an odor's identity due to prior experience, assessed by means of a test of cued odor identification, and odor pleasantness ratings in children who exhibit ongoing olfactory learning. Ninetyone children aged 8-11 years rated the pleasantness of odors in the Sniffin' Sticks test and, subsequently, took the odor identification test. A positive association between odor identification and pleasantness was found for two unpleasant food odors (garlic and fish): higher pleasantness ratings were exhibited by those participants who correctly identified these odors compared to those who failed to correctly identify them. However, we did not find a similar effect for any of the more pleasant odors. The results of this study suggest that pleasantness ratings of some odors may be modulated by the knowledge of their identity due to prior experience and that this relationship might be more evident in unpleasant odors

L’animal : un objet d’étude

Homo animal est : l’être humain appartient lui-même au règne animal, mais il est le seul à projeter sur les autres membres de ce vaste ensemble un regard analytique. Prendre l’animal comme objet d’étude, c’est le propre de l’homme. « Chez absolument tous il y a quelque chose de naturel, c’est-à-dire de beau » : Aristote, s’apprêtant à détailler les Parties des animaux, prévient son lecteur que les animaux les plus répugnants méritent eux aussi l’attention du scientifique, car ils témoignent des règles auxquelles se conforme la nature, que le philosophe a à cœur de percer. Cette longue tradition d’étude du monde animal, renouvelée aujourd’hui par les découvertes sur le génome, a pris de multiples formes au travers des âges ; mais elle a toujours suscité d’amples questionnements, non seulement sur la nature des animaux eux-mêmes, mais aussi, plus largement, sur leur place dans le monde et, en retour, sur celle de l’homme lui-même. Le Congrès national des sociétés historiques et scientifiques rassemble chaque année universitaires, membres de sociétés savantes et jeunes chercheurs. Ce recueil est issu de travaux présentés lors du 141e Congrès sur le thème « L’animal et l’homme »

Olfaction, réactivité hédonique et expressivité faciale chez l'enfant

This paper briefly surveys the research on the origin and development of human olfactory preferences, and shows the interest to analyse the structure of facial responses to odours in order to clarify the role of ontogenetic and environmental factors in emotio- nal expressiveness. The review of the studies did not allow : (i) to draw reliable conclusions about neonatal predispositions to discriminate the hedonic component of odours ; (ii) to strengthen the view of a strong developmental discontinuity of hedonic responsiveness to odours around 5 years, particularly for unpleasant-to-adults odorants. The potential role of experiential factors in the acquisition of preferences is suggested, at least for some odours, because of correlations between age, odours familiarity and hedonic responsiveness. Research on facial responses to odours suggest that morphological and temporal structure of facial movements is flexible and able to reorganize when display rules operate reflecting children's attempts to manage their facial expression.Cet article présente brièvement les travaux sur l'origine et le développement des préférences olfactives. Il montre de plus l'intérêt d'analyser la structure des réponses faciales aux odeurs afin de préciser le rôle de facteurs ontogéné tiques et environnementaux dans la régulation des expressions émotionnelles. L'examen critique des travaux ne permet pas : (i) de se prononcer sur la présence d'une prédisposition précoce du nouveau-né à discriminer la valeur hédonique des odeurs; (ii) de confirmer l'hypothèse d'une discontinuité de la réactivité hédonique aux odeurs de 3-5 ans à 6-15 ans, plus particulièrement pour des odorants désagréables pour des adultes. Les corrélations observées entre l'âge de l'enfant, la familiarité de l'odeur et la réactivité hédonique suggèrent, au moins pour certaines odeurs, le rôle de l'expérience dans l'acquisition de préférences olfactives. L'analyse de travaux sur la nature des réponses faciales aux odeurs suggère que la structure morphologique et temporelle des mouvements faciaux est flexible et probablement régulée par des règles d'émission, lesquelles prescrivent les modalités particulières de contrôle des expressions faciales adoptées par les enfants en fonction du contexte social.Soussignan Robert. Olfaction, réactivité hédonique et expressivité faciale chez l'enfant. In: Enfance, n°1, 1997. pp. 65-83

Modifications épigénétiques et effets protecteurs de l’environnement socio-affectif de l’enfant : une revue

Correspondance : [email protected] audienceOver the past decade, a growing number of works in psychology and neuroscience have documented the potential involvement of epigenetic mechanisms (e.g., DNA methylation) to account for the effects of early life stress and adversity on the development of psychopathological or psychiatric disorders. More recently, the protective or beneficial effects of some factors in the child's social and affective environment, via changes in epigenetic marks (e.g., epigenetic reversibility), have been explored. We briefly review a number of these works that suggest (i) possible associations between variations in the quality of social environment dimensions/characteristics and changes in DNA methylation, and (ii) the moderating effects of therapies/ behavioral interventions on epigenetic changes and the development of psychopathological disorders. Finally, some limitations of these works are also briefly discussed as well as expected directions for future research.Au cours de cette dernière décennie, de nombreux travaux de recherche en psychologie et en neurosciences sont venus étayer l’hypothèse de l’implication potentielle de mécanismes épigénétiques (e.g., méthylation de l’ADN) pour rendre compte des effets des expériences de stress et d’adversité précoces sur le développement de troubles psychopathologiques ou psychiatriques. Plus récemment, les effets protecteurs ou bénéfiques de facteurs de l’environnement social et affectif de l’enfant, via des modifications de marques épigénétiques (e.g, réversibilité épigénétique), ont été explorés. Nous passons brièvement en revue quelques-uns de ces travaux qui suggèrent (i) des associations possibles entre des variations de la qualité de dimensions/caractéristiques de l’environnement affectif et social et des modifications de la méthylation de l’ADN, ainsi que (ii) des effets modérateurs de thérapies/d’interventions comportementales sur les modifications épigénétiques et le développement de troubles psychopathologiques. Enfin, serons discutés aussi brièvement quelques limites de ces travaux et des directions de recherches futures souhaitables

Approche ethologique des processus d'adaptation d'enfants de l'ecole maternelle a l'ecole elementaire

SIGLECNRS T 58397 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc