Chapter 1 – The Science of Smells
Humans have a sense of smell, or olfaction, which is located in the olfactory epithelium in the nose.
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The olfactory epithelium contains about 350 different types of odorants.
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Odorants interact with these receptors and are transduced a neural signal that travels via the olfactory nerve to the olfactory bulb in the brain.
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Humans can also smell through their mouth, a process called retronasal olfaction, which is important for the perception of food and taste.
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Chemoreception, or the ability to respond to chemicals in the environment, is not limited to olfaction and includes other senses like taste and touch.
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Humans are incredibly good at sensing the chemical world around them, and every time they meet someone, they are taking in chemicals from that person and process information about them subconsciously.
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Tears of others impact hormone levels in powerful ways, and there is an alternation of ease through which humans can breathe through one nostril or the other, reflecting an underlying dynamic of the nervous system.
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The olfactory system is sensitive to trauma, and a common cause of losing one’s sense of smell is a contra coup injury to the back of the head, which severs the olfactory nerve.
Chapter 2: The Olfactory System and Memory
The olfactory system is unique in that it has the ability to regenerate neurons in the adult mammalian brain, unlike other systems.
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The olfactory system follows a pattern of convergence, where all receptors of a given subtype converge to one location in the bulb, called a glomerulus.
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The first exposure to a smell generates a particularly robust representation in the brain, which is why olfactory memories are formed more easily and maintained longer than other types of memories.
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Olfactory training can help maintain and recover olfactory function by neurons electrically active and maintaining their connections.
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Humans have a remarkable sense of smell is added to cooking gas, are an example an additive that is used to give gas a smell so that we can detect it
Chapter 3: The Incredible Sense of Smell
Humans have an amazing sense of smell, with a detection threshold of 0.2 parts per billion.
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This is demonstrated by an odorant called estro tetraenol, which can be detected at 10 to the negative 12 molars in the liquid phase.
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Humans can track odor like a dog, as demonstrated by an experiment where a chocolate bar was in the grass and a blindfolded participant successfully tracked the scent.
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The experiment was where participants were deprived of sensory input and asked to track a consistent odor path in the grass.
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The study found that people could track the scent right off the bat, and with training, the rate-limiting factor became the speed at which they could crawl.
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The study also found that people performed better with two nostrils and one centralized nostril, as they could take advantage of the information that comes from separate nostrils.
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The nasal cycle, where the high-flow nostril is low a half hours on average, is linked to the in the out system.
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A wearable device called the nasal halter has been developed to measure nasal airflow and is being used as a disease marker, with the ability to differentiate between ADHD and non-ADHD adults and those on Ritalin.
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The direction of causality between the unilateral smelling through one nostril and the shift in the autonomic nervous system is currently being studied.
Chapter 4: The Importance of Nasal Inhalation in Cognitive Processing
Nasal inhalation plays a role in cognitive processing and neural activity.
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The brain processes information on inhalation, which is why nasal inhalation is crucial for cognitive function.
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Studies have that people perform better on visual-spatial tasks during nasal inhale breathing.
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Nasal breathing is also beneficial for overall health, including dental and reducing the risk of infections.
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Olfaction is closely linked to brain function, and loss of the sense of smell is an early sign of neurodegenerative such as Alzheimer’s and Parkinson’s’.
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However, olfaction has not been effectively digitized, which is why olfactory tests are not as convenient as visual or auditory tests.
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Congenital anosmia, the lack of a sense of smell from birth, is associated with social and health issues and is often diagnosed late.
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Common syndrome, a condition associated with hypogonadal development in men,- O all mammals, including humans.
Chapter 5: Lab Me & Olfaction
Blood work is important it allows you to monitor markers such as hormone markers, lipids, and metabolic factors that impact your immediate and long-term health.
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Lab Me has a personalized dashboard that can help you address nutrition-based, behavior-based, and supplement-based approaches to move those values to optimal ranges for you.
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Lab Me was the first and still is the only company in the world that offers at-home diagnostic level CBC blood testing.
Lab Me also offers a neurotransmitter profile test that can help spot deficiencies present in your brain chemistry.
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Olfactory behavior is the subconscious and conscious coding of identification of people based on the or other aspects of their chemistry.
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Handshaking is an odd behavior that is understood, but research has shown that people tend to touch their noses more frequently after a.
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A study on click friendships found that people who click with each other tend to have more similar body odor than random pairs, this similarity can predict friendship and other positive.
Chapter 6: Bruce Effect and Human Olfaction
The Bruce Effect is a phenomenon in which a pregnant mouse exposed to the odor of a non-stud male will miscarry the pregnancy.
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This effect is mediated by the vomeronasal organ, a structure in the nose that is part of the accessory olfactory system.
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Humans are thought to lack a functional vomeronasal organ, but the evidence for this is not conclusive.
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Humans may still experience pheromonal effects, including those related to reproductive behavior.
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A study of couples experiencing unexplained repeated pregnancy loss that women who experienced this had a greater ability to identify their spouse’s odor than control women.
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These women also showed a greater brain response to stranger body odor in fMRI scans.
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This suggests that there may be some pheromonal effects in humans related to reproductive behavior, although more research is needed to confirm this.: The Influence of Chemo Signals on Human Behavior
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The term pheromone is a problematic term and is mostly used to describe behavior.
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Humans emit chemo signals from their that influence other humans’ behavior and physiology.
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The smell of fear is a widely studied chemo signal that influences other humans’ autonomic and romantic partners to leave articles of clothing with each other scent to bring about positive is a chemo signal that promotes social buffering and is highly conserved throughout mammalian evolution.
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The Tyler Aggression ParadigmAP) is a standard paradigm used to study human aggression, where participants play a game against a computer algorithm that is programmed to be a jerk.
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In the experiment, participants can blast the other participant with a loud noise, and the noise level can vary from low to very high.
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Eva Mishore, a graduate, used hexadecane in the TAP experiment and found that participants who were exposed to hexadecane were less aggressive than those who were not hexad signal which promotes social buffering and reduces aggression.
Chapter 7: The Effects of Hexadanal on Aggression
Hexadecanal men and increase aggression in women.
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The molecule was tested on participants playing a video game, and the results showed a significant decrease in aggression in men and an increase in aggression in women.
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The molecule was found to increase activity in the left angular gyrus, an area of the brain involved in social appraisal.
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The default brain reaction is aggression, and hexadecanal increases the control that the left angular gyrus has over aggression in men, while it lets it roam free in women.
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The molecule is the most abundant semi-volatile in baby head odor, which suggests that it may play a role in maternaliveness and offspring survival.
Chapter 8: The Power of Tears
Tears are a bodily liquid that we emit in emotional situations where nonverbal have puzzled scientists for a long time, and even Charles Darwin wrote an entire chapter on tears in his book The Showing of the Emotions in Men and Animals without a functional antecedent.
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Tears may function as a chemical signal and emotional tears can be harvested and studied in the lab.
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Emotional tears are completely odorless, but when sniffed, they can cause a pronounced reduction in testosterone within about 20 minutes to half-hour in men.
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Tears also have a dampening effect on brain activity under an arousing state, lowering activity in the hypothalamus and the fusiform gyrus.
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Sning tears may lower aggression in men, as tears contain a pheromone that lowers aggression in rodents.
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Tears are not uniquely human, as identical effects have been discovered in rodents and dogs emit emotional tears when they reunite with their owners.
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The tear study faced criticism from a lab in Holland that had built a career on the notion that emotional tears are human.
Chapter 9: The Influence of Dogs on Oxytocin
Oxytocin is a hormone that is influenced by the presence of dogs and their tears in humans.
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The speaker shares a personal story about his attachment to his dog and how it made him he could keep producing tears.
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Dogs may hijack the circuitry intended for child rearing, which could explain why people are so attached to their dogs.
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Dogs shed emotional tears and are uniquely human A study attempted to replicate the effect of tears on arousal in women but failed to do.
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The speaker offered to fund a graduate student to replicate the study with him, but the party refused.
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Replication is key in science, but it is rarely a pure replication.
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The out subconscious signals are divorced from the smell we perceive, such as the nutrient content of food.
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There may be potential olfactory perceptual similarity in metabolic products, which play into the coding of olfactory space.
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The sense of smell is not as subjective as people think, and humans are incredibly similar in their olfactory perception.
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People are biased by outliers, which may explain why there is a misconception that olfactory perception is highly subjective.
Chapter 10: The Science of Smell and Digitizing Smell
The population has different preferences for smells, with some loving cilantro and guava while others hate it, but there are about a thousand odorants in the lab that can be tested.
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Out of a hundred odorants, be in total disagreement, but these outliers do not change the fact that we are more similar than we think.
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The poor application of language to olfaction is one reason why we perceive smells differently, as we do not have the same anchors as we do in other sensory systems.
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The most important term in measuring sensory systems is similarity and it can be used to quantify how similar individuals perceive smells to be.
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The rules linking odor structure to perception have only recently been developed, and our lab has had a mini breakthrough in predicting the perceptual similarity of any two molecular mixtures with high accuracy.
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The next step is to find a set of components called outer primaries that can be used to mix any that can be perceived, and a proof of concept test has been done with four different odorants, with violets being the first odor ever transmitted over IP.
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While Google has already published two papers on digitizing smell, the best and most creative outgun large groups, and the race is on to solve the problem of digitizing smell.
Chapter 11: Potential olfaction Digitization
Olfactionization has the potential to revolutionize medical diagnostics by detecting specific metabolic processes and smells with diseases.
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Once olfaction digitization reaches the equivalent of 4K vision audition, it will be possible to have an electronic nose in the bathroom that can perform diagnostics all the time.
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However, this technology is not close to being developed yet and will likely take many years to achieve.
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The potential applications of olfaction digitization extend beyond medical diagnostics and could include dating apps and transmitting smells through technology.
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The speaker emphasizes the importance of the spirit of science and the drive to work without external validation but also acknowledges the immense gratitude and appreciation for those who care about their work.
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podcast host expresses his admiration for the speaker’s work and the impact it has had on the scientific community and the world at large.