Mini Episode: Neuroscience of Taste

[ Music ] >> We're Lane and Sheris, two certified clinicians who are obsessed with neuroscience and learning all the secrets behind the power of our brains. From alcoholic blackouts to phantom limbs, brain freezes, orgasms, and more, these bite-sized episodes cover all the human experiences that are fascinating to us. This is the Mini Brain Loan Podcast. >> Hey, Lane. So last month, we talked about the neuroscience of smell. >> Mm-hmm. >> Now, are we going to continue down this path for this episode? >> I think because there was some question as to what was going on with COVID and why people were losing their sense of taste and why things tasted on. We started with smell, right, because smell is where we first noticed it in some of the symptomology, but I think the other half of that is definitely taste. So I think we have to expand on it. >> Nice. >> And do the other side of that coin since the two are very interconnected. >> Yeah, no, that makes so much sense. And great call out, yes, to last month's knowing that we dove into neuroscience of smell one because it's really cool. >> Yeah. >> It turned out to be way more interesting than we expected. >> Right. >> But also-- >> And we do it terribly. >> Yeah, right. >> Yeah, oh my gosh, how much we suck at smelling that was so funny. But then also that tie into that there was an episode request that someone was specifically curious about why COVID took away these things. So when happens when you lose your sense of smell is what they're asking for. Yeah, totally. >> Absolutely. >> Then which is a common question with all of that, with all of what happened with COVID. >> Yeah, absolutely. >> Yeah, let's talk about guistation. I love how these simple things have such weird science words. >> Right. And both of them are a chemosensation because they're breaking down chemical responses. >> Love, love, it's like poetry. >> Right. So to talk about the neuroscience of taste, I think it's like anything else we've talked about like pain or smell. We have to talk about, or hearing, right. We have to talk about what happens to experience all this. So we'll do that same kind of direction. >> Love that. I actually love to that. It's not a visual because it's a podcast, but a sort of internal visual that I'm a doctor at. >> Yeah. >> So play something on your tongue. We should have grabbed snacks for this episode. And there will be receptor cells waiting. >> Okay. >> If you touch your tongue right now, you can sort of feel that there are, it's a texture to it. >> Yeah. >> Whether those bumps. >> Yeah. >> Exactly. >> Those bumps people think of are taste buds. They're actually not. They're called papilia. And your taste buds are actually on the walls around the papilia and inside the surrounding areas, surrounding those bumps. >> So they're almost like the crevices or like the cracks in crevices, like around or an inside. >> I sort of like the grout. >> Yeah. >> In your tile. >> Yeah. >> That's where your taste buds are. >> Oh, wild. >> So in your taste buds, each one has receptor cells and they have between like 50 and 150 receptor cells. >> In one taste buds. >> That's right. >> And they are really geared specifically towards two tastes. And that's sweet or bitter. >> Ooh. >> But we'll get more into all the specifics on that in just one second. So depending on the combination of the flavor of that chemical you're putting on your tongue, this starts a chain reaction. So when the thing you're tasting and its specific taste interacts with those receptor cells, it can then depolarize the cell. So in other words, it's actually changing the electrical charge of the cell. >> Wow. So it's just like doing, it's like, oh, this is different. We're going to do something different. >> Mm-hmm. >> Oh, wild. >> Yeah. >> So you taste something. So you taste something. It hits those receptor cells. That receptor cell potentially then depolarizes and sends a chain reaction up through your brain. Ooh. Okay. Interesting. So depolarization that change in electrical charge causes a neurotransmitter to be released. Or neurotransmitters, right? Our phone calls are taxed our DMs. >> Yes. >> And it can cause reactions on the cells in your intestines that can stimulate the production of insulin. >> Oh, okay. Okay. Wow. So taste is triggering insulin. >> Yes. >> And you actually taste something twice. >> You taste it twice. >> You do. So eating sugars or glucose will cause your body to produce way more insulin than if you inject it because you taste it first on your tongue and second inside your intestines. And that notification of sugar means more insulin will be reacted, which you don't get if you inject it. >> Wow. So you're literally getting double. >> Mm-hmm. >> Holy smokes. Is that the same? Now we're focusing, maybe it's just from this word spoke, focusing on sweet. Is that the same for bitter food? So bitter is an interesting reaction. A 2011 study showed that it increases your appetite in the first 30 minutes. But after 30 minutes, it will cause the reserves of this to like dwindle and prolongs the sense of fullness. So originally you want to eat more after 30 minutes. It's like, mm-hmm. No, just kidding. And it takes you longer to want more. >> Whoa. Okay. I don't want to interrupt the brain direction that we're heading. So remind me to jump back to this because that makes me feel like you could plan, I don't want to get into like dietary things, but you could plan the food that you eat throughout the day to stay better satiated. >> Potentially. >> Wild. Okay. Which explains why a lot of people ingest coffee early in the morning and then forget to eat breakfast. >> Yes, the bitterness. >> Mm-hmm. >> Wild. >> So the stimulation of specific neurons focuses on the sensations that travel on the cranial nerves to what's called your solitary track otherwise known as your NST, Nuculus of the solitary track, NST. That's according to the Institute of Health and States. It is a major sensory nucleus on the dorsal mandula that receives cardiovascular visceral, respiratory, gustatory, orotactical information. So heart information, blood information, organs, breath, taste, and touch. That's what your NST is doing. It's taking it, everything. >> Yeah. >> Well, except for smell. Well, great call out. Oh my gosh. >> Because smell is located so close to everything else. >> Yes. >> So this is located in our brain stem. So hand model of your brain, that's your wrist, right? Like palm wrist. That's where your NST is located. Information is then sent from your NST to your thalamus. So if we remember right hand model of the brain, that is your thumb. That is buried in the center of your fist to the hand model of your brain. And it's sent to the thalamus or limbic pathways to the gusseatory neocortex, which we have not talked about. >> Yep, that's new. >> Right? But we have talked a lot about what it's made out of, which is your anterior insula. >> We have talked about insula. Would you remind me again just out of curiosity? What other episodes we talked about in insula? We started talking about insula in season one episode two in empathy. >> An empathy? >> Yes. >> Because insula is activated when we feel a sense of disgust. >> Yes, that's right. >> So we've talked a lot about it because any time we have some of that adverse repulsed reaction, that's your insula. Well that's where your gusseatory neocortex is, which makes sense because to survive, we need to make sure that we weren't putting absolutely disgusting toxic things into our system. >> Yeah, that makes sense. >> So when you have a reaction to food that's negative, that's your insula, that's firing. >> Holy crap, does that mean your insula totally fires when you're younger? Maybe it's a developmental thing for bitter food? Because little kids, younger kids normally don't like bitter things. They don't like the taste of coffee. They don't like that sort of stuff. But as you get older. >> Yeah, that's a really curious piece that I wanted to know more when I was researching this is what causes us to change and move as somebody who used to have a major sweet tooth and now cannot eat anything sweet whatsoever, but loves coffee and dark chocolate. >> And like vinaigree stuff, what makes you like those specific things? >> Yeah. >> Yeah. >> Yes, I think that's some of the developmental wise, but what's interesting is in your tongue, though receptor for bitter and the receptors for sweet are on top of each other, like their besties. In the brain, there's tons of space. And there's a whole lot of space for neurons in between that. So especially as the brain is developing, there's so much changes. >> There's so much changes going there. >> Yeah, all those pathways. >> No, no, they're building. >> Right, which may be why our palate needs to develop and change. >> Wild. >> Oh my gosh. >> But especially for little ones, it makes sense, like do not put that in your mouth, it's disgusting. I mean, we still have that even without the insulin reaction, right? So it makes sense on an evolutionary standpoint to try to do a lot towards bitter. >> Yeah. >> Specifically, actually, with bitter is something we have more receptors of than I think almost anything else, probably because it's so focused on survival. >> How is bitter connected to survival? >> It's good to eat something and talk to someone. >> If you eat something that's going to make you sick, it's often better. >> These are the first foods. >> Things that aren't sweet are probably not great. >> Yeah. >> So evolutionary wise, we're really geared towards sweet or bitter because sweet is simple. It is definitely food, it's definitely calories and especially when we were running around in caves, you needed a high caloric diet to survive. Because again, humans weaker, slower, not as cool as most of the mammals for getting food, right? So we just had to grab whatever we had and because we decided to stand up right, our intestinal system changed so that we need to eat all the time and we can't find food as easily. So yeah, sweet, fatty foods were huge to us and needed all of those positive benefits. Whereas we needed the bitter receptors to be like, "Don't eat that, but it'll kill you." Gotcha. Gotcha. So that's where we have all these specific receptor cells geared towards. Cool. All of that is happening in the Gusseutory Neocortex, which is made up of your interior insula. Your insula is about being grossed out among other things and your upper column is involved in sort of what's happening to me and how do I make sense of it? Fair. Which tracks. Yeah. Because a lot of food is what's happening to me and do I want to continue doing this or is it sped, in, according to small, then he's in and green, studies suggest, "Flavor perception begins to emerge in the insula and it has a significant value as to how we code odors and taste." Specifically, citing, quote, "patients with insular lesions." So lesions on their insula were found to display both Gusseutory and Dolphactory Sensory deficits. Oh my gosh, not as good. Difficult with smelling, difficult with taste. Whoa. Wonder what's going on with COVID. Whoa. Hello. We've sped on the COVID research team. Right. Well, especially because we know from COVID, not only did people lose their sense of smell and/or their sense of taste, and sometimes for long periods of time, right? But also that things would change the way that they taste. Yeah. That seemed different. Yeah. That something you liked, all of a sudden tasted disgusting, that is shown we've got research that says when you damage that part of your insula, that will happen. Wow. This is so cool. This topic is making me think of so many different things, too. So let me know if this just needs to be another mini episode. What is, what do we think the effect is on the insula during pregnancy? Because that's where you'll get really wild taste like cravings of weird things, or like wanting to eat things that they used to absolutely hate, or something like that. I think we need a neuroscience of pregnancy. Okay. We'll see if there's room for this season. If not, we'll save it so stay tuned. More to come in season three. The insula has specific value in regards to how we code things. So we have some agreements on why we code. This is what we got into in the neuroscience of smell. Is smell and taste are going to be really fascinating because it's to look into the science of it teaches us how we actually code stuff, which is essentially keen to how we remember and how we sort of sort through data. Yeah. In regards to that, we know that there are some flavors we agree on that are definitely happening in a certain way and some that aren't. And there's more research that needs to happen because as we mentioned in smell, there's a whole lot we actually didn't study on this because we got really excited about sight and then forgot about things. So this is true for taste as well. So we have some agreements. Our agreements are sweet, bitter and umami for certain. Oh, okay. Sweet is a simple carbohydrate that binds to a receptor cell to send off a reaction. Better, as we mentioned, same receptor cell, that's happening the exact same way through coupled proteins. Both of them basically are exactly the same. Okay. It's just which receptor cell. So that coupled protein might attach to a certain receptor cell and then that's bitter or this coupled protein might attach to a receptor cell and then that's sweet. Sure. Absolutely. Umami as a G coupled receptors is also as discussed is not as restricted to this tongue, but also has receptors in your stomach intestines and your pancreas, which Biza Trivoli states quote, "Aid to the digestive process by influencing appetite and regulating insulin production. They have also been found in the airways where they have an impact on respiration and even in sperm where they affect maturation." Wow. So umami is great. Yeah. Love, love. And so other flavors are up for debate as they could be a mixture of this or a different perception. And we're still trying to figure out exactly what we're coding and why, but we know those three are for certain. Salty, we know doesn't have a salty receptor per se the same way that the other three do, but it enters through sodium channels and then basically follows a very similar pathway. So it doesn't need those receptors goes in a different way. Yeah. Sour operates very differently. According to Zucker, there's no specific place in your brain for sour, but Zucker argues this is probably because it's also painful. He states quote, "When you put a drop of acid on your finger, it burns. You aren't getting a sour element taste. So your brain has a conflict on this particular taste. There's the taste, but there's also a possible reaction for sensory that your brain needs to pay attention to. So it's essentially conflicted. I'm guessing spice also would have the exact same thing." Yeah. That makes sense. Because your brain is like food and out. Yeah. Absolutely. So it needs to sort of process it differently in a way that sweet does not have, right? You don't have out with sweet. Yeah. Wild. Also important to note is connected to a lot of what we talked about recently, which is pleasure. In the neuroscience of chemical dependency, we discussed that this will impact your ventral-tagmental area in your nucleus accumance, right? Those are big for all things good. Additionally, Tindall and All states a role of the ventral palladium neurons in coding hedonics. Hedonics is essentially a title we gave things to say this is discussing pleasant or unpleasant sensations. Okay. So hedonic is like a really like that I really don't like. It's sort of the pain pleasure that we talk about in terms of addiction, right? We go through withdrawal, that's pain. We go through pleasure when we get something. That's your hedonic shift. Gotcha. That makes sense. Yeah. The scale sort of amounts is. Ventral-pladium sits inside your basal ganglia. No big surprise. It's hanging out with motivation and rewards. Specifically encoding hedonics. Do we find it pleasurable or not pleasurable? Do I want to do this again? Do I not want to do this again? This is all connected to right. Our mini episode on motivation or chemical dependency. They're all going to come in together in this. Yes. This is an exciting area of research because we're really trying to further understand how this adonic shift can play into addiction when they impact your nucleus acumbents and your ventral-tagmental areas. Thus that cause for motivation that could be causing that rewiring. Wow. So we're doing a lot right now to figure out why the brain says yes I like it, give me more of it up into the point where I don't forget to eat, I forget to sleep, I forget to do the things I need to do. Right. Right. Well how does that impact my motivation and reward to do other things? Yeah. And food and taste is a part of that because we know that's something you can become addicted to. It's one of those things that can rewire your brain because a lot of pleasurable things can. Yes. So this is kind of bringing us to a wildest taste matter. So taste can curb or increase appetite, which could be helpful to know as you brought up for not wanting to get into people's dieting, but as an awareness of I'm eating something better, this means I may not have room for something later. Sure. Absolutely. Yeah. Kind of planning out maybe sweets shouldn't be at the end of a meal. Right. Maybe they should be. Or I mean if you're into dark chocolate, that should be at the end of your meal. That sounds great. Yeah. A great bitterness. Yes. Yes. So maybe starting your meal with dark chocolate and then 30 minutes into that meal, you'll be done and then you'll be full for longer. Great hypothesis. I'm loving this. So we have that benefit, right? Understanding how that insulin reaction, the more we can understand that, the better we can help out with those particular diseases, right? The more we know this is also connected to how we connect for pleasure, how we code for pleasure. Let's us know a lot more about the brain. We are in an area of research where we're really trying to figure out what makes food pleasurable or unpleasurable and knowing this could allow for more control over pleasure and not rewiring the brain in negative ways as we discuss in the neuroscience of addiction. So anytime we're discussing something pleasurable, taste is one of them. This gives us more insight to help us honestly reduce chemical dependency. Holy crap. Right? Because it's all about how do we code? And we need to code for taste. That's an easy one. Wow. Take away, study the simple things. Yeah. And learn the bigger things. It's one of the reasons why when this was suggested, I was like, that sounds actually really cool because we in this podcast, it wouldn't be bad for us to have some building blocks as to what we do without question and taste and smell or something we do without question. Yeah. And taste specifically like smell also tells us a lot more about memory. There are memory triggers. You remember the taste of something and maybe where it was that you ate it or something like that. We mentioned already how smell you can smell something immediately be transported back to a place or it would be reminded of a person who smelled that way or something like. Yes. Because smell is so connected. It's two jumps. It's two jumps between smell and memory, which in your brain is nothing. So that's huge, right? But it's also a very fascinating part is when we talk about memory as humans, we think, Oh, memory, that's just like a part of your brain or that's just we've got a grandma neuron that remembers grandma. None of it works that way. All essentially, all your brain is doing all the time is remembering and coding. Remembering coding and learning are main factors to your brain being successful, because that's literally how you're operating today. You're remembering how to speak, right? You remembered the words for the English language. - I remember having to put on pants this morning. - Yeah, you remembered, you remember pieces to literally function. This includes just smelling, eating. Those are based things that we have to do. - Yeah. - We have to remember, oh, that smells pleasant. I should go into that cave 'cause that's gonna have raspberries growing in it, and guys, where I don't go in case. (laughing) Or remembering those berries, they smell kind of weird. I shouldn't eat those, those are gonna kill me. Right? So all of that is connected to smell and taste, and our fundamental building blocks to helping us function, but are then built up to how we can remember great symphonies or information about neuroscience or a variety of things, right? So the more we can understand how the brain remembers things, the more we learn about what our brain is doing all of the time. In addition to understanding more as according to Duali, this could have major impacts on treating a lot of conditions all the way from diabetes to infertility. - How infertility? - 'Cause it affects sperm. - Oh, right, yeah, we mentioned that. - Yeah. - Whoa. - Right? - It really smokes. - All of this from taste. - Right? - It's just so cool. - So simple, does so much. - Yes. - So I also had to play on this episode in terms of what we can hypothesize as we discussed. We kinda have a good hypothesis. People who are studying COVID come at me. I would love to know if I'm wrong, sounds great. But I would hypothesize that COVID damages your insula, which is kind of fascinating to potentially know. We know it's causing some brain fog. If your insula is really close to your basal ganglia in regards to motivation, that tracks for brain fog. - Mm-hmm. - And if people are talking about COVID makes them taste weird for months, I would argue this is potentially a thing and how the code ink could have gotten scrambled. - Totally. - Which is really insightful and potentially helpful. - Yeah. It's also a great reminder too, that you don't taste in your tongue. - No. - You taste in your brain. - Yeah, and specifically determine if you like it or not. - Yes. - In your brain. Which then leads us to sort of an interesting takeaway, which we didn't do as much for smell. But I think we can do a little bit for taste, which is if you wanna like the taste of something, neuroplasticity. If you want to learn to like the taste of something, it is about essentially helping your brain code, right? Basal ganglia motivation, "Hey, I like this thing. Hey, this thing hasn't appealed to it, right?" And being able to be present with that. And we know that we can do that. Although we actually even talked about this in the neuroscience of racism, it is difficult to completely rewire for something we are adamantly against. If our insulifiers too hard, it's hard to get over that particular reaction. It's easier to go from like bad to neutral and neutral to good. So being aware of how big of a jump you're looking to make and how much time it may take to rewire your brain. - Yeah. - But yeah, be mindful with your food. Be present with the smell of it, with the taste of it, with the texture. Learn the piece of it that are appealing. And you'll help rewire your brain, not only to build on more of that thickening in your pre-frontal cortex, which then decreases anxiety, which makes you calmer. But maybe I'll learn to like the taste of dark chocolate. - Thanks for listening to the Brain Blown Podcast. This podcast is created and produced by Lane and Cheris with music by James Austin. To learn more about this episode, head over to brainblownpodcast.com for script notes, visuals, and any resources we mentioned. And hey, if you have any topics you're curious about, or wanna learn more on, we'd love to hear about it. Send us an email to [email protected] or reach out via social media to connect. (gentle music)