The mysterious origins of gut feelings | Emeran Mayer | TEDxUCLA

hello anybody who has watched Magnus Walker's got feelings realizes that this is a hard act to follow however I do want to start with my presentation with a personal story that illustrates the power of God feelings that all of you probably have experienced yourself up to the age of 17 I worked in my parent's confectionary store and that's that business had been in the family for six generations I made pastries and cakes for all joys all kinds of joyous occasions but I particularly enjoyed making fancy chocolates or voltage shapes and forms I started to associate the sweet aromas of chocolate and vanilla and and other ingredients with the seasons and with major holidays without realizing without conscious awareness that I was laying the blueprints for my future career studying the complex interactions between food the mind and the gut I'm sure that most of you have made many gut based decisions in your own lives and that you've used the expression gut feelings casually in many social conversations and you're not alone world leaders military commanders rock stars Magnus Walker and millions of other ordinary people have used the same mechanism to make fundamental decisions about their life when it was time to make a decision about college I agonized over this over the decision to become the seventh generation leading the family business or embark on a career in science or medicine after spending months of creating long plus-minus lists and listening to friends and family members I finally started listening to my gut feelings and to the great disappointment of my father decided against the family tradition several years later after finishing medical school I made another gut fundamental gut based decision which may be abandoned a secured faculty position at a Munich University Hospital for a open-ended future as a scientist as a junior scientist in a famous research center at UCLA that at the time was a magnet attracting research from all around the world studying emerging science of signalling molecules from the GI tract during the first few days when I arrived at my new job I realized this was light-years away the activities I was doing isolating purifying and testing molecules from vast amounts of pig intestine that we had to collect in the slaughterhouse in the morning it was light-years away from the charm of working in a chocolate business back home however after a few months I did realize that this was actually a very fascinating topic because at the same time reports appeared in the literature that the identical molecules that we isolated from the gut were also found in the brain as well as in many animals and plants and yes they were also used by microbes to communicate with each other at the time we didn't really pay much attention to this last example it was considered to be an oddity I wouldn't have him actually imagine in my wildest dreams that I would stand up here 35 years later and talk to you about this revolutionary concept that the microbes now got using the gut brain communication system is able to influence your emotions influence our gut feelings and may play a significant role even in your brain health a few years ago up till a few years ago if you had asked any scientist what he would he or she would consider the most sophisticated example of how a microbe can influence mammalian behavior they probably used the example of Toxoplasma gondii a parasite that like most parasites require two hosts for successful reproduction the the cat and the mouse the cat's intestine being essential because it's the only place for this organism can reproduce now here comes the remarkable intelligence the reason I bring up this example the remarkable intelligence of this organism in order to optimize the chances for the Toxoplasma cysts getting to the cat's intestine for reproduction the organism is able to get into the brain of the mouse and change the inborn fear of cats into a fatal sexual attraction towards the cat so even the mere smell of cat urine will attract the cat greatly enhancing the chances that it ends up ultimately in the GI tract of the cat now when NPR picks up a topic and ERUs it on the Morning Edition you know it's got to be something of significant importance and interest to a large public this happened about two years ago when a story aired about the when the first story aired on on NPR about the wondrous interactions between the gut microbes our normal gut microbes not the parasites that can influence our behavior and our emotions 24 hours a day from the day we were born to the time that we died most of these experiments unfortunately we're only performed in in rats and mice so at that time there was really no evidence that this would have a counterpart and in humans this is particularly remarkable because we have a hundred trillion of these microorganisms in our GI tract ten times more than human cells in the entire body and a hundred times more than brain cells we have in our brain so one of the questions that comes up immediately I mean how did these microbes living in the gut in this vast universe internal universe how did they communicate with with the brain now let me give you a couple of examples how we think that this may be working and then get into the details of the mechanisms so some of these experiments that were reported several years ago people would have considered the imaginations of a mad scientist so they may get to the first example so when stool samples were taken from a genetically timid introvert Mouse and translated into the colon of an outgoing extrovert Mouse train these mice became just as timid as the ones that were the stool sample came from obviously the stool sample contains the gut microbes so a second example equally remarkable and pretty close to home is that a genetically altered mouse strain that is obese because it's over consuming food when it was transplanted into lean mice without any of their own bacteria so-called germ-free mice these mice also started to gain weight all of a sudden and the majority that weight gain was due to the voracious appetite suggesting that something that microbes somehow the microphones were able to get into the mouse appetite centered on the hypothalamus messed it up and shut off the control mechanisms that normally stop the food intake so coming back to the question how can these microbes that live in the gut this sort of ugly environment how would they get to the super clean to a clean supercomputer the brain and make these phenomenal changes so you probably probably think about the gastrointestinal tract this is old-fashioned factory if a model from the early Industrial Age they would process mainly processed food and is and being concerned about calories and nutrients getting into your system you probably have not heard about the change in the conceptualization that we have of the GI tract is probably the most sophisticated information gathering organ paling really the NSA that collects information at the gut level and sends it to the brain 24 hours a day every millisecond even when you sleep now that just let me explain to you a few examples that illustrates how the system does that so our gut has its own nervous system the second brain 15 million neurons the same size if you put them all together as your spinal cord 20 different type of sensory cells and hundreds of receptors that are specific for specific kinds of molecules that either come from the microbes or from food components the gut also has the largest component of your entire immune system and it's basically acting they're very closely adjacent to the lumen of the gut and influencing your entire immune response and finally there is about 20 specific cells containing hormones different kind of hormones or chemical messengers that they play a role in a wide range of functions from appetite control to craving and and as well see some other their intriguing functions as well so all these cells in a gut what they have in common is they are connected to the brain they are signaling to the brain all the time this vast amount of information is processed by the brain and influences many of our baseline functions as background emotions and how we feel in the morning when we wake up now here comes the interesting part of it the most interesting part so just a very thin layer less than an entire cell and sometimes that layer is even permeable if you have a leaky gut so most of you have heard about this and the alarms go up this tiny layer separates these trillions of bacteria humming around inside of you and interacting with via these various sensory mechanisms with these cells that I just mentioned you so it seems so one of the questions is why do we have this complicated communication systems in the gartner brain so one plausible explanation is it's there primarily for the reason to transmit this phenomenal wisdom it's contained in our trillions of microbes back to the brain and as as we know the brain is not just sitting there but the brain sends signals back to the gut level as well which I'll show you in just a minute now let me highlight this these communication channels in one example serotonin probably most of you have heard about serotonin because it's the target of antidepressant drugs serotonin reuptake inhibitors that most psychiatry is still today believe act primarily on the brain however in reality only 5% of the total body serotonin is actually at the brain level 95 percent is stored in these endocrine cells within you got separate less than a millimeter from trillions of bacteria and food components that can influence both the production but also the signaling of these molecules to the to the brain it's interesting that serotonin is not just contained in our body but it's one of those Universal messenger molecules it is in dark chocolate it's contained in the peels of banana and very high concentration and also the microbes have the ability to produce their own serotonin precursors they can be taken up by these cells so mentioned a second ago that the brain just doesn't sit there receiving this terabyte amount of information every millisecond it can also respond and influence these cells releasing serotonin or other stress mediators such as norepinephrine into the gut lumen in response to stimulus to a stressor to an emotional state now why would it these serotonin or the northen Efrain do inside the gut well it interacts with receptors that these microbes have very similar to our own receptors and essentially the brain can stress out you got bacteria it's also been speculated that an alteration in the serotonin system could lead to an negative influence and the emotions based on unhappy microbes that stimulate an abnormal amount of this messenger so one of the questions I mean how did the microbes figure out how to communicate with us this is an interest interesting question is it that we that that the microbes learned these neurotransmitters from us the design or did we pick up this information from the microbes if you look at evolution microbes have inherited it have inhabited plant earth for close to four billion years that this was a lot of time to learn to communicate with with each other it's primarily it was a time for communication and the the optimization of communication between multicellular organisms only 500 million years ago one of these guys started came up with the idea it might actually be beneficial to live inside the GI tract of one of the most primitive marine mammals the Hydra this turned out to be so successful this symbiotic relationship because the microbes in the gut got free rent got free transport through the vastness of the ocean and the host got substances that by itself could not would not produce it was so successful it was adopted over the next several hundred million years by all the animals species in in the world about a million years ago we as humans took on this communication system and the bacteria and if you look around from bees to ants to cockroaches and any other animal has the same system so this is something universal not really unique to us humans so until recently and I mentioned this in the beginning the only data that we had on this brain I mean gut microbiome brain communication was really based on the respect tacular animal experiments and it was remarkable another single study had dealt with the with with the question is their human counterpart to this communication so we decided to do a study a very simple experiment where we took where we fit young healthy women a probiotic cocktail containing yogurt for four weeks and we looked at their brain responses to emotional stimuli and to our amazement the study showed that there was actually a decreased responsiveness to these stimuli in these healthy women now before you throw away your valium or stop your early morning meditation you have to realize these were completely healthy individuals and we did not see any effect on their emotional makeup just the response at the brain level was decreased in a follow-up study we we asked another intriguing question possibly more interesting is there a correlation between the organizational like the signatures of these microbes in your gut and the architecture of your brains of the brain structure and again we found that there was a correlation of the white matter tracts that connect different parts of your brain with the pattern that these individuals had in their gut microbial composition so one plausible explanation could be that this is actually something that formed early on in life because we have our microbes from the from the day we were born and possibly even before that in in in our intestines and there's a few unique things about the early life phase we get these microbes when we pass when an infant passes through the vaginal canal during the vaginal delivery the first inoculation but then there's also later influences of early life in terms of diet and expand hygiene that would that would influence the composition the position is unstable in the first three years of life so anything that happens there is a fundamental effect on the later lifelong trajectory of this of this programming the same thing is true about the brain the brain is actually 15 years of development so both are work in progress during the first during the first 3 years now I had a unique opportunity to look at an aspect of this early life programming that only became relevant to the microbiome much later and actually just a couple of years ago when a paper appeared that native Native Americans living in the jungle of the Orinoco the headwaters of the Orinoco had a very unique composition of the microbes the infant's so even before dietary differences between North America infants in North America and infants living in the jungle so all were nurtured by their by by only breast milk so one unique thing about this one for the most remarkable experiments for me during that time was one night I left this village from the hammock that we were staying in and when Dodman in the in the jungle it was a moonlit night quiet and I saw this woman squatting over a banana leaf and delivered her baby onto this banana leaf only surrounded by these invisible billions of microorganisms that inhabit this natural environment this is only a speculation but I think we can assume that many of the programming many of the trajectories that our mic our microbiome takes and the influence it has on the brain so it's very early and it's illustrated by these by these natives living a hunter-gatherer prehistoric lifestyle have very different micro biomes even later in life that something may be going on here so let me just close with with 1/x with one practical implication of this so there have been a dramatic increase in diseases such as autism multiple sclerosis and Parkinson's disease in last 50 years at the same time we have noticed a dramatic change in in our diet particularly in the way food is produced and processed and in the use of antibiotics is it possible that these influences by influencing the gut microbiome and all of these disorders have been identified recently to have a component of altered gut microbiota and also bring out interactions is it possible that these changes in our diet have actually led to this this dramatic increase in in these diseases in addition to many others like obesity and so let me close with the with the thought a better understanding this is obviously all has vast implications the better understanding of the complex interactions and these Universal dis Universal connectedness of our gut microbiome with the world around us with the food we eat the way we were born the way our food is processed once you understand the science and the connectedness of this I would predict it has major implications of how we see ourselves the world around us and how we see our health in what we have to do to men off to my Zarya health thank you very much you

Channel: TEDx Talks

Views: 45,464

Keywords: TEDxTalks, English, United States, Science (hard), Bacteria, Biology, Depression, Health, Medicine, Research

Id: nkmE31QUU4o

Length: 21min 19sec (1279 seconds)

Published: Tue Jul 07 2015