[Music] um thank you so much lisa for that fascinating talk and the visuals were amazing um we will move on to the audience q a section now um and we have quite a few coming in so um i think we'll start with tina she asks as the triune brain is history how do you see the role of the amygdala um the fight flight and freeze are these a myth too well the amygdala is not a myth you you every everyone who has a neurotypical brain we all have amygdalas um but what's really interesting about the amygdala you know the mental is kind of like the rock star you know of the brains like the one that all the journalists like to write about and you know that we all know the name of and stuff the amygdala though is um its job is not emotion or fear it's not fear it's not fight or flight it's not even you know having anything to do with feeling um if i took your brain and i stuck it into a i stuck you into a brain scanning machine and i showed you images that you've never seen before just scenes of things that you've never seen before people that you've never seen before your amygdala would uh increase in activity quite a bit and that's because really your amygdala is what its job is really is to signal uh the rest of the brain that there's something either uncertain or novel or important to survival that you need to know more about and therefore you must learn so really your middle is there really to signal the rest of the brain to learn something new to improve your ability to predict later and that often involves not just you know changing the chemical concentrations in your brain but also getting your body ready to do something but so really you can think about your your amygdala as kind of like the sentinel that tells the rest of the brain hey we have to learn something new here um so that we can predict better in the future for you know fight and flight and these kinds of you know these are actions that um are highly contextual so the things that we think of as reflexes are actually really contextually executed even for example like in a two-hour old zebrafish larval zebrafish that's been alive in only a couple of hours what that animal does yeah you know when there's a looming darkness over it depends on a bunch of contextual factors like where is it how far is it um what you know so no animal really only has like one fight or one flight kind of hardwired reflex we actually have more like a menu of actions that we can take and these are the actions that your brain prepares automatically with prediction sometimes these sometimes others but it's a very automatic kind of thing when your brain is predicting which is doing all the time even your ability to understand the words that i that are coming out of my mouth is prediction and um they're they're basically what your brain is doing is it's preparing your actions uh uh without your awareness um and usually what your brain is doing is checking those those plans those predictions against the state of your body in the world sometimes though when your life is really on the line your brain's not going to wait it's just going to execute the action and that's what we call fight or flight reflexes thank you um from daniella our brains may anticipate water coming into the blood leaving us feeling less thirsty when we drink but this doesn't seem to happen with food the advice when trying to lose weight is to wait 20 minutes before having a second helping because it takes our bodies that long to register it why is it different to thirst what a great question so in a sense um i mean in one sense part of the machinery is the same right because it takes 20 minutes for the um the cells in your gut to send signals up to the brain to say that there is enough glucose here and you can stop eating the problem is that all been exposed for many many many years so let me back up and just say one thing normally if you eat a carbohydrate or protein or fat everything's going to be at one point you know translated into glucose so let's just talk about carbohydrates even though proteins turn out to be the thing that's actually more important to regulate your brain is really concerned with well your brain's concerned with all of them but protein turns out to be super important but let's just talk about carbohydrates um normally when you eat something sweet it it there's a certain amount of energy in it right calories that you take in and you um your brain will signal i mean your gut will signal to your brain but all of us since birth have been exposed in the western world to sweeteners that are artificial sweet doesn't always indicate glucose does it sometimes it doesn't and your brain has learned that over time so for some people their eating is actually much more tied to um they do stop in advance because they're not exposed to sweeteners or other artificial substances but most of our food that we eat is actually pseudo food and meaning that it's been um it's been sort of designed in a sense to trick us into keeping to keep eating um so i have to tell you i'm not i don't i don't work for a food company no one in my family does when i first when you know i first had my daughter 22 years ago and people told me that goldfish were like really bad for her and she should only be eating you know whole foods i was like no forget like what is this this is like you know what propaganda is this but it's one of these times where the data are just so crystal clear on this that i'm absolutely convinced that um this is right we don't understand everything about eating and how you know the relationship between the gut and the brain and how hunger and glucose signaling works but we understand enough to know that there is not a single artificial sweetener that will ever pass the threshold of my house because it interferes with your your brain's ability to predict on the basis of taste and vision what and smell what the calories what the glucose is that you can get out of that food and that's why you keep eating so if you eat more slowly and you allow yourself your you allow that 20 minutes to happen you're gonna have a your brain will have better control over your eating um than it would otherwise thank you um from sophie is there a difference between the impact of positive and negative emotions on our brain well sophie emotions don't impact your brain they are constructed by your brain so um sometimes people like to say it's a very popular thing to believe that emotions are in your body like your body keeps score of negative things that's actually not true emotions are in your brain your brain keeps score your body is the score card the answer to your question is yes there is a difference but some negative emotions well all emotions when your brain constructs them are um usually involve you preparing to do something or learn something so they're likely to be more moments that are of more expense than say sitting quietly and thinking although if you're sitting quietly and thinking and you're learning and you're you know having to um take in a lot of information and process it that you hadn't anticipated or that is novel that can also be very expensive too um but what i would say is more that the real problem is not really negative versus positive emotion the real issue is are you when you make you know when your brain is making withdrawals are you making deposits do you get enough sleep do you eat well are you eating pseudo food or are you actually eating healthful food are you getting enough exercise do you have enough social contact with other people which actually allows your body budget to work more efficiently assuming that you have good relationships with them these are the things that are really important and you know stress for example all stress is is your brain preparing for a big metabolic outlay that's it um glucose is i mean i should say a cortisol is not a stress hormone it's a hormone that gets glucose into your bloodstream really fast so right before you get out of bed in the morning you have a cortisol surge because you're about to spend to get out of bed right before you exercise you have a cortisol surge so the issue is are you replenishing what you spend if you don't then you're driving your body budget into a deficit state and that is unhealthy and the other thing i will add is that you know western culture to some extent you know cultivates bankrupt body budgets in people um that there's more to say about that than i have time for but if you just think about it you know nobody sleeps enough people on exercise enough we're very sedentary a lot of us are looking at screens which contain uh wavelengths of light that trick our brains into thinking into like confusing day and night and which causes circadian rhythm disorders which are actually really bad for your metabolism each of these things um you know social media the kind of casual brutality that people have created and the way that they speak to each other um none of these things is like a deal breaker but each one adds a little metabolic tax and it adds up over time like slowly slowly slowly over time you know it's kind of like water dripping on a metal pipe it's not gonna it's not gonna hurt the pipe the first time the tenth time or even the thousandth time but eventually that water is gonna bore a hole through that steel pipe and the same thing is true for these little metabolic taxes they add up over time so the issue isn't positive versus negative emotion the issue is not whether something feels good or feels bad the issue is whether or not you're making investments in your body budget that you're you're making deposits after you spend and that you're not your brain isn't in a situation where it's it's preparing preparing preparing to deal with stress um uh in a chronic way the next question comes from alexis has your research on the body balancing budget and interceptive network influence your perspective on the conscious and subconscious mind well alexis yes it has um like i studiously avoided um consciousness the discussion of consciousness in seven and a half lessons because my goal was really to write a small book of essays for people who don't usually read neuroscience or even science right i wanted a book that um would be quick to read and fun and you know give people some tidbits of neuroscience they could like entertain their friends with at a party because you know when i was writing the book we still all went to parties um my husband calls it the first neuroscience beach read um but the idea was that you know that the topics would linger with you as you went through your day and maybe would leave you thinking about things about human nature so but consciousness is a tricky one it's really hard to write about in this way um but what i will say is that yes um i absolutely it has absolutely changed particularly actually understanding brain evolution um to the extent that i understand it has really quite substantially changed my views on the neural basis of consciousness and if you're looking for a good book on that topic i would really recommend um the um book by uh the philosopher peter godfrey smith called metazoa it he you know or or any of his scientific papers or i guess philosophical papers um i don't agree with everything in that book but i think it's a really nice treatment of um brain and evolution and or nervous system evolution and consciousness i think it's i think it's really uh i think it's really well done and my views to some extent build off some of the um insights that he describes in that book of course i read the papers but you know but the book i think is also really nice summary for people um the next question comes from an anonymous attendee how would you explain conditions like tinnitus what is the brain hearing and is it real that's a great question my my husband actually suffers from tinnitus so he um was a heavy metal drummer um in the day and he wore earplugs but they weren't sufficient um and now he's almost deaf actually without hearing aids and it's very tragic in some ways for him um because he has very loud tinnitus but tinnitus is like um phantom limb pain your brain has wired itself to your the map of your cochlea and i mean that's the you know the inner part of your ear with the little hair cells that allows you to hear allows you to translate vibrate it translates vibrations in the air into sounds well the sounds are in your brain but that that that information makes its way the vibrations make its way to your brain and that's translated into sounds and when that in from when the input goes missing the brain can simulate it meaning when when your brain i use the word prediction a prediction is is a concrete thing when your brain is changing the firing of its own neurons in advance of sensory input tinnitus is caused people scientists now think tinnitus is caused by the brain changing the firing of its own neurons when there is no sensory input so your brain is replacing the the sense data that would come from the world um and as a consequence you um you know are continually hearing a sound um where there's no um you know sense data coming in to cancel it there's no sense data coming in to correct the brain and say hey there really there really is nothing going on in the world there so you can stop that firing of those neurons because they're not that's not really representing what's happening in the world this doesn't mean that it's all in your head well i mean it is all in your head but it doesn't mean that it's imaginary you're really hearing the sounds because everything you hear everything you see everything you feel is in your head it's in your brain your brain sees your eyes don't see your brain sees your your ears don't hear your brain hears your brain is changing the firing of its own neurons and then it waits for sense data from the world or from the body to either confirm those predictions or change them or modify them so with tinnitus it's lost the brain has lost some of its constraining information and so the activation continues unconstrained and your hearing continues it's just like hearing a song in your head that you can't get out of your head what people call ear worms but you're continuing to hear it because there's nothing from the world that will cancel it out um well thank you so much lisa i think that's all the time we have for this evening um i just want to thank you so much for such an interesting talk and um taking the time to answer all the questions from the audience um for everyone joining us from home thank you for joining us um and you can always check out more of our upcoming events at howtoacademy.com um or join our subscription service how to plus to come to all of our live talks and get our entire video archived as well um lisa thank you so much my pleasure thanks so much you