ECRO – Virtual Online Meeting 17th – 18th September 2020
The European Chemoreception Research Organization (ECRO) meeting, organized by Thomas Hummel, was originally scheduled to take place in Dresden, Germany. Due to the corona outbreak, the original meeting could not take place but thankfully we were able to continue the meeting in a virtual format. NOSE members Ilja Croijmans and Laura Speed were virtually on the ground, and share some of their highlights of the latest research in Chemosensory Science.
The first keynote of the conference was given by Ilona Kadow who presented her research on the role of dopaminergic neurons in drosophila smell and taste. In drosophila olfaction, olfactory information is first processed by antennae and then directed to two regions of the brain: the mushroom body and the lateral horn. Kadow conducted a range of experiments testing the responses of dopaminergic neurons in the mushroom body to different odors and states of the drosophila. The dopaminergic population was found to code for odor and taste valence, hunger level, reproductive state, and whether the fly was walking or resting. Overall, the dopaminergic system reflects both innate and state conditions.
Asifa Majid, co-founder of NOSE, proposed the hypothesis that olfaction and language are symmetrically connected. For example, when English speakers are presented with an odor, they struggle to correctly name it, demonstrating a weak link from odor to language. On the other hand, evidence suggests that language does not affect odor perception directly, but instead affects judgements about odor. Therefore, the connection from language to olfaction is weak too. However, Majid emphasized the value in considering non-western languages and cultures where multiple odor lexicons have been described. Finally, initial evidence from experimental work teaching participants new odor words suggests that one of the causes of poor odor language could be insufficient input in terms of odor-related talk. Majid stressed the role of learning and early childhood experiences that shape our thinking about smells. For example, many parents discourage their children when they notice and start talking about smells in their environment (‘Yuck, that’s bad!’), whereas they tend to promote and encourage children to talk about what they see and hear (‘Look, a big bird of prey! Can you hear it shriek?’).
Symposia day one
After the keynotes, the audience virtually divided into smaller symposium rooms. One of the symposia was on chemosensory communication between people, organized by Ilona Croy. Laura Schäfer presented work on how smell is involved in mother-child bonding. When mothers recognize their babies by their smell, this is related to more secure attachment in the mother-child bond. She further investigated what function baby smell might have. Many people would acknowledge that baby smell is the best smell in the world. Schäfer proposed that this almost universal pleasant smell might have a kind of ‘olfactory cuteness’ function: if babies, helpless as they are, are perceived as cute, this can ignite caretaker feelings in people that smell (or see, for that matter) them, improving the baby’s survival chance.
Next, Lucie Kuncová presented the results of a study she conducted with Jan Havlicek: they found that the body odor of one’s partner has a strong resemblance with the body odor of the other sex parent. In lay-men’s terms: someone’s boyfriend’s body odor strikingly resembles their father’s body odor, and someone’s girlfriend’s body odor resembles their mother’s body odor, although less so than for men’s body odors. Next was Enzo Pasquale Scilingo who presented the plans for project POTION, a Horizon 2020 ERC project that sets out to investigate the chemosignalling of emotions between people. Mem Mahmut then presented findings that suggested single men smell differently than men in a relationship. The underlying mechanism Mahmut proposed lies in the testosterone system: body odors are more intense in men with higher levels of testosterone, and single men tend to have higher levels of testosterone. The session was closed by Agnieska Sorokovska, who presented findings on sensory compensation, where one sense takes over when another sense fails. She presented results that suggested no evidence for a better (i.e., more sensitive) sense of smell in people who are blind or visually impaired. This contrasts with a commonly-held belief that people who lose their sense of vision develop their other senses. An alternative explanation for this false idea is that greater attention to smell in people who are unable to see may be perceived as better perception.
On the second day of the conference, Noam Sobel presented the latest finding from his group’s member Eva Mishor. Their work shows that hexadecanal can act as an aggression pheromone. The findings suggest that this depends on the gender of the person who smells this molecule: in men who smell this molecule that resembles the smell of cardboard, it decreases aggression, whereas in women, it seems to increase aggression. The conflicting pattern of results in men and women might be explained by evolutionary pressures for mothers to protect their children from the aggression of their fathers, as was suggested by Mishor and Sobel.
Symposia day two
One recurrent theme at ECRO 2020 was an issue pheromone researcher Tristram Wyatt raised earlier this year, that chemosensory research needs to address reproducibility problems in research. Not only should research conducted on human chemosignalling (i.e., communication between people via smells and tastes) be replicated in different labs and stand the test of time, findings from the lab should also hold up in the noisier contexts of the real world. Open science, which includes making data, methods and results accessible, offers one part of the solution to these issues. Conducting the research in larger groups of people that better represent general populations, in ecologically valid (‘real world’) contexts, provides another part of the solution. Jonas Olofsson and Tristram Wyatt organized a symposium on how we can improve the reproducibility of chemosensory science. This symposium had a strong methodological character: First, Anna Dreber presented the link between pre-registration and the predictive value of studies. Pre-registration involves explicitly stating your methods and analysis steps in advance before the data is collected. Afterwards, when analyzing the data, these steps should be followed. This prevents the researcher from making decisions during the analysis that would give a better outcome, but would not match the original hypotheses. By pre-registering studies, the link between the a-priori hypotheses and how the data is analysed, and thus the answer to those hypotheses, is fixed. This way, there is less room for data and analyses manipulations. Next, Wyatt describe how we can use pre-registration when designing studies. Pre-registration is not yet commonplace in chemosensory science, but should be, according to Wyatt. Marco Tullio Luiza next underscored the need for validated instruments – and presented how we might test and substantiate the validity of our experiments. Finally, Valentina Parma talked about how she improved the reproducibility of her studies, and how this might be applied to other chemosensory studies.
NOSE members Monique Smeets and Ilja Croijmans organized a symposium to address the question of how to take human chemosensory science out of the lab. NOSE member Laura Speed presented work on crossmodal associations with odor. By conducting experiments in a museum, Speed was able to collect data from a diverse sample of participants, and show that certain crossmodal associations observed in the lab can generalize to more real-world contexts. In a separate study, a large online screening test discovered a small group of participant with a rare form of synaesthesia: odor-color synaesthesia. Speed’s research showed that individuals with odor-color synaesthesia are better at naming odors and better at discriminating odors than control participants are. This suggests odor-color associations support odor language and perception.
In the next talk, Jasper de Groot presented how virtual reality (VR) might be used to provide real-world context to smells that are presented in the lab, to make the experiments more ecologically valid, and outcomes more generalizable in the real world. In this experiment, they show that a cleaning context (i.e., washing laundry), presented with the smell of laundry detergent, causes more cleaning behavior in participants. But without the VR context, participants showed most cleaning behavior in the clean air condition.
The next speaker, Mirjam van den Brink, highlighted the importance of adapting the methods used in experiments to a specific population, in her case children with cancer. Cancer, and chemotherapy, has profound effects on how children perceive tastes and smells, which in turn affects what they eat. Good nutrition is important, especially for these patients, as it improves their chances of a good outcome of the disease, and improves their overall quality of life. This underscores that understanding the effects cancer and chemotherapy has on smell and taste is incredibly important.
The last talk of this session was presented by Jonathan Williams, who presented his work on the air composition in cinemas and football stadiums. By analyzing air composition, Williams and colleagues were able to accurately predict when football players scored a goal, or predict what kind of scene was played during the movie. By looking at the air composition between different movies, they were further able to predict what age classification a movie had.
The session was a diverse set of talks, and together with the session by Olofsson and Wyatt, provided many inspiring examples of how we can make chemosensory science even better!