Auswirkungen von Androstadienon auf das menschliche Verhalten

Androstadienon (AND) ist ein Chemosignal, das z.B. im menschlichen Körperschweiß vorkommt. Im Rahmen dieser Arbeit soll systematisch gesammelt werden, ob in der Literatur konsistente Einflüsse von AND auf bestimmte Verhaltensreaktionen bei Menschen aufgezeigt wurden bzw. ob und wie AND unter besonderen Voraussetzungen wirkt. Dies wurde mittels systematischem Review erzielt. Mittels PRISMA Leitlinie wurde die Literatur strukturiert und analysiert. Die Ergebnisse von 24 Originalstudien, welche Verhaltensdaten unter Einfluss von AND veröffentlicht hatten, wurden in vier verschiedenen Kategorien miteinander verglichen: Auswirkungen auf das soziale Verhalten, auf die emotionale Reizverarbeitung bzw. Emotionsbewertung, auf die Attraktivitätsbewertung und Partnerwahl sowie Wachsamkeit und Gedächtnisleistung. Aufgrund unterschiedlicher Studiendesigns, unterschiedlicher Stichproben, Studienaufgaben, Konzentrationen und Präsentationen von AND sowie Inhomogenität der berichteten Ergebnisse konnte kein konsistenter Effekt von AND auf das Verhalten von Menschen aufgezeigt werden. Zum anderen wurde die Frage gestellt, ob AND unterschiedliche Einflüsse auf Menschen hat, welche den Geruch von AND als angenehm oder unangenehm empfinden – hierfür wurden die Teilnehmenden einer Verhaltensstudie anhand Mediansplits hinsichtlich der Bewertung, wie angenehm sie die AND-Lösung empfunden haben, in zwei Gruppen geteilt und Unterschiede in Bezug auf zwei Aufmerksamkeitsprozesse untersucht. Vergleichbar zum systematischen Review konnte auch in der Verhaltensstudie kein konsistenter Effekt der subjektiv wahrgenommenen Annehmlichkeit von AND auf unterschiedliche Aufmerksamkeitsprozesse festgestellt werden. Zusammenfassend zeigt sich eine Inkonsistenz der publizierten Auswirkung von AND im systematischen Review. In der eigenen Studie konnten wir keinen Effekt der Annehmlichkeit von AND auf Aufmerksamkeitseffekte zeigen. Es bleibt daher offen, welchen Effekt AND tatsächlich auf menschliches Verhalten ausübt und zukünftige Forschung wird zeigen, welchen (konsistenten) Einfluss Chemosignale auf die menschliche Kommunikation haben

Human Olfaction And Mate Choice

Prevalent beliefs in both scientific and popular culture are 1) humans have a poor sense of smell, and 2) smell plays a minimal role in social behavior. However, this consensus is shifting with researchers even suggesting olfaction influences mate choice. Still, studies of odor-based communication in humans remain inconclusive because of poorly designed experiments, scant replication studies, and publication bias. Thus, the goal of this dissertation was to return to first principles and build a solid foundation for the study of human olfaction and mate choice. Chapter 1 provides a rich overview of human olfaction and odor-based communication, revealing the poor methods used in studies of pheromones and body odor. Chapter 2 investigates the impact of a putative female pheromone, copulin, on men’s mating psychology, using rigorous methods (e.g., a placebo-controlled, odor-masking design) and a large sample (n = 243 men). The findings reveal that when the limitations of prior pheromone research are addressed, there is no evidence that copulin is a pheromone. Chapter 3 asks whether some individuals smell more or less attractive to the opposite sex. Studies of mate choice from an evolutionary perspective often begin by investigating whether individuals of one sex agree on the attractiveness level (e.g., facial attractiveness) of individuals of the opposite sex. For comparison, a uniform methodology was used to assess agreement in judgments of physical and vocal attractiveness, modalities in which evidence of shared preferences is generally accepted. No differences were discovered between modalities. Therefore, to the extent shared preferences exist for faces and voices, there is also evidence of shared preferences for body odors. Chapter 4 examines the relationships between independent multisensory judgments of attractiveness (i.e., face, voice, and body odor attractiveness). For men, modalities of attractiveness did not covary. However, in women results indicate weak covariances between all modalities. Moreover, a latent general attractiveness factor (i.e., common fitness correlate) modestly contributed to covariances between modality-specific attractiveness. Together, these findings suggest historical views of human olfaction as unimportant were misguided. In fact, the evidence demonstrates body odor plays a similarly important role to physical and vocal attraction in human mate choice

The human body odor compound androstadienone increases neural conflict coupled to higher behavioral costs during an emotional Stroop task

The androgen derivative androstadienone (AND) is a substance found in human sweat and thus may act as human chemosignal. With the current experiment, we aimed to explore in which way AND affects interference processing during an emotional Stroop task which used human faces as target and emotional words as distractor stimuli. This was complemented by functional magnetic resonance imaging (fMRI) to unravel the neural mechanism of AND-action. Based on previous accounts we expected AND to increase neural activation in areas commonly implicated in evaluation of emotional face processing and to change neural activation in brain regions linked to interference processing. For this aim, a total of 80 healthy individuals (oral contraceptive users, luteal women, men) were tested twice on two consecutive days with an emotional Stroop task using fMRI. Our results suggest that AND increases interference processing in brain areas that are heavily recruited during emotional conflict. At the same time, correlation analyses revealed that this neural interference processing was paralleled by higher behavioral costs (response times) with higher interference related activation under AND. Furthermore, AND elicited higher activation in regions implicated in emotional face processing including right fusiform gyrus, inferior frontal gyrus and dorsomedial cortex. In this connection, neural activation was not coupled to behavioral outcome. Furthermore, despite previous accounts of increased hypothalamic activation under AND, we were not able to replicate this finding and discuss possible reasons for this discrepancy. To conclude, AND increased interference processing in regions heavily recruited during emotional conflict which was coupled to higher costs in resolving emotional conflicts with stronger interference-related brain activation under AND. At the moment it remains unclear whether these effects are due to changes in conflict detection or resolution. However, evidence most consistently suggests that AND does not draw attention to the most potent socio-emotional information (human faces) but rather highlights representations of emotional words

The effects of lavandula angustifolia on animal and human laboratory models of anxiety

Lavender (Lavandula angustifolia) is a popular treatment for stress and mild anxiety. Currently, there are few reliable investigations of its efficacy because cognitive and associative effects of odours can confound pharmacological effects. Some of these problems can be overcome by testing the effects of odours in animals, and by using orally-administered lavender in sealed capsules in human participants. In addition, a criticism of current studies is that most employ short-term administration of lavender, even though humans most often use lavender over longer time-periods. There are two parts to this thesis. The first part addressed two questions; whether lavender odour exhibits anxiolytic effects in animal models of anxiety, and whether chronically administered lavender is more effective than acutely administered lavender. The second part addressed the question of whether, in a randomised double-blind placebo-controlled trial, orally-administered lavender exhibits anxiolytic effects in humans. This thesis makes three significant contributions: First, these studies provided a validation of the gerbil elevated plus-maze model of anxiety in both male and female gerbils, a model that has only previously been validated in female gerbils (Varty et al., 2002). Second, the studies on gerbils have shown that both lavender and rose essential oils have anxiolytic effects, which, rather than dissipating following acute odour administration (Cooke & Ernst, 2000), potentiate over time. Lavender’s effects were particularly apparent in female gerbils on measures related to risk-assessment, a behaviour that has been related to the human anxiety trait of worry (Blanchard, Blanchard, Griebel, & Nutt, 2008). Third, lavender had a clear dose response effect in reducing baseline anxiety in humans when tested acutely via oral administration, although there were no effects when more severe anxiety was induced. The route of administration and the fact that iv lavender had dose response effects indicate that lavender’s effects are not caused by psychological qualities of the odour, but are more likely to be due to direct pharmacological effects. Again, and comparable to results in gerbils, lavender’s anxiolytic effects in human females were more noticeable, particularly during the anxiety task and in the recovery phase of the study. In summary, prolonged exposure to lavender odour relieved anxiety in a validated animal model of anxiety, and orally-administered lavender alleviated mild anxiety in humans. In both cases, results were more prevalent in females