Essentials: How Smells Influence Our Hormones, Health & Behavior | Dr. Noam Sobel

Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science based tools for mental health, physical health, and performance. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. And now for my discussion with Doctor. Noam Sobel. Doctor. Sobel, Noam, Thank you. I must say I am extremely excited for this conversation. I've been a huge fan of your work. And today I'd love for you to share with us all about the amazing landscape of chemo sensation, particular olfaction or sense of smell, and some related perceptual abilities or subconscious abilities, including pheromones, etcetera. To get everybody on the same page, I'd like to just start off by asking, what are the major components of our ability to smell? Obviously, where I like to think it involves the nose at some level. It does. If you could just give us the top contour, or even deep contour, if you like, of the parts list and the various roles they play. Primary olfaction is referred to as orthonasal olfaction, that is through our nose, we sniff, and sniffing is a big thing. Well, I have a sense we might talk about that a lot today in all sorts of contexts. So we sniff in through our nose, and to answer your general question of the organization of the system, so airborne molecules travel up our nose a distance in the human of about six or seven centimeters to about here, where they interact with... I will use the word sheet of receptors, but sheet is a bit misleading here. It's not a sheet, it's very convoluted. We have about 7,000,000 such receptors lining a structure known as the olfactory epithelium. This is the sensory surface of the olfactory system, the olfactory epithelium. Again, probably about six or 7,000,000 receptors in the human. In the human, probably of about three fifty different kinds. So that's amazing. That means a meaningful percentage of your genome is devoted just to this, just to the kinds of olfactory receptor subtypes you have in your nose. So odorants interact with these receptors here in our epithelium, where they undergo what is referred to as transduction, that is the odorants are dock at a receptor and turn into a neural signal. And this neural signal, in fact, action potentials, not gradient potentials of any kind, propagates via the olfactory nerve through the thinnest part of our skull, which is perforated. It has a lot of holes. The nerve goes through those holes and synapses at the first target in the brain, which is the olfactory bulb. The pattern of that synapsing follows what's referred to as the most extreme case of convergence in the mammalian nervous system. More specifically, what happens is that all the receptors of one subtype converge to one location in the bulb. And this location is referred to as a glomerulus or an enplural glomeruli. And that may …