Essentials: How Your Brain Works & Changes

**Andrew Huberman** (0:00)
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. For today's podcast, we're going to talk about the parts list of the nervous system. Now, that might sound boring, but these are the bits and pieces that together make up everything about your experience of life, from what you think about to what you feel, what you imagine and what you accomplish from the day you're born until the day you die. By the end of this podcast, I promise you're going to understand a lot more about how you work and how to apply that knowledge. So let's talk about the nervous system. The reason I say your nervous system and not your brain is because your brain is actually just one piece of this larger, more important thing, frankly, that we call the nervous system. The nervous system includes your brain and your spinal cord, but also all the connections between your brain and your spinal cord and the organs of your body. It also includes, very importantly, all the connections between your organs back to your spinal cord and brain. So the way to think about how you function at every level, from the moment you're born until the day you die, everything you think and remember and feel and imagine is that your nervous system is this continuous loop of communication between the brain, spinal cord and body and body, spinal cord and brain. In fact, we really can't even separate them. It's one continuous loop. The way to think about how the nervous system works is that our experiences, our memories, everything is sort of like the keys on a piano being played in a particular order, right? If I play the keys on a piano in a particular order and with a particular intensity, that's a given song. We could make that analogous to a given experience. Our brain is really a map of our experience. We come into the world and our brain has a kind of bias towards learning particular kinds of things. It's ready to receive information and learn that information, but the brain is really a map of experience. So let's talk about what experience really is. What does it mean for your brain to work? Well, I think it's fair to say that the nervous system really does five things, maybe six. The first one is sensation. Sensation is a non-negotiable element of your nervous system. You have neurons in your eye that perceive certain colors of light and certain directions of movement. You have neurons in your skin that perceive particular kinds of touch, like light touch or firm touch or painful touch. You have neurons in your ears that perceive certain sounds. Your entire experience of life is filtered by these, what we call sensory receptors, if you want to know what the name is. Perception is our ability to take what we're sensing and focus on it and make sense of it, to explore it, to remember it. So really perceptions are just whichever sensations we happen to be paying attention to at any moment. Perception is under the control of your attention. And the way to think about attention is it's like a spotlight, except it's not one spotlight. You actually have two attentional spotlights.
Anyone that tells you you can't multitask, tell them they're wrong. And if they disagree with you, tell them to contact me. Because in old world primates of which humans are, we are able to do what's called covert attention. We can place a spotlight of attention on something, for instance, something we're reading or looking at, or someone that we're listening to. And we can place a second spotlight of attention on something we're eating and how it tastes, or our child running around in the room, or my dog. You can split your attention into two locations, but of course you can also bring your attention, that is your perception to one particular location. You can dilate your attention, kind of like making a spotlight more diffuse, or you can make it more concentrated. This is very important to understand if you're going to think about tools to improve your nervous system. Attention is something that is absolutely under your control. The nervous system can be reflexive in its action, or it can be deliberate. Deliberate thoughts are top down. They require some effort and some focus, but that's the point. You can decide to focus your behavior in any way you want, but it will always feel like it requires some effort and some strain. Whereas when you're in reflexive mode, just walking and talking and eating and doing your thing, it's going to feel very easy. And that's because your nervous system basically wired up to be able to do most things easily without much metabolic demand, without consuming much energy. But the moment you try and do something very specific, you're going to feel a sort of mental friction. It's going to be challenging. So we've got sensations, perceptions, and then we've got things that we call feelings slash emotions. And these get a little complicated because almost all of us, I would hope all of us, are familiar with things like happiness and sadness or boredom or frustration. Certainly, emotions and feelings are the product of the nervous system. They involve the activity of neurons. But as I mentioned earlier, neurons are electrically active, but they also release chemicals. And there's a certain category of chemicals that has a very profound influence on our emotional states. They're called neuromodulators. And those neuromodulators have names that probably you've heard of before, things like dopamine and serotonin and acetylcholine, epinephrine. Neuromodulators are really interesting because they bias which neurons are likely to be active and which ones are likely to be inactive. A simple way to think about neuromodulators is they are sort of like playlists that you would have on any kind of device where you're going to play particular categories of music. So for instance, dopamine, which is often discussed as the molecule of reward or joy, is involved in reward and it does tend to create a sort of upbeat mood in when released in appropriate amounts in the brain. But the reason it does that is because it makes certain neurons and neural circuits, as we call them, more active and others less active. Okay, so serotonin, for instance, is a molecule that when released tends to make us feel really good with what we have, our sort of internal landscape and the resources that we have. Whereas dopamine, more than being a molecule of reward, is really more a molecule of motivation toward things that are outside us and that we want to pursue. And we can look at healthy conditions or situations like being in pursuit of a goal, where every time we accomplish something in route to that goal, a little bit of dopamine is released and we feel more motivation, that happens. We can also look at the extreme example of something like mania, where somebody is so relentlessly in pursuit of external things like money and relationships, that they're sort of in this delusional state of thinking that they have the resources that they need in order to pursue all these things when in fact they don't. I want to emphasize also that emotions are something that we generally feel are not under our control. We feel like they kind of geyser up within us and they just kind of happen to us. And that's because they are somewhat reflexive. We don't really set out with a deliberate thought to be happy or deliberate thought to be sad. We tend to experience them in kind of a passive reflexive way. And that brings us to the next thing, which are thoughts. Thoughts are really interesting because in many ways they're like perceptions, except that they draw on not just what's happening in the present, but also things we remember from the past and things that we anticipate about the future. The other thing about thoughts that's really interesting is that thoughts can be both reflexive, they can just be occurring all the time, sort of like pop-up windows on a poorly filtered web browser, or they can be deliberate. We can decide to have a thought. And a lot of people don't understand or at least appreciate that the thought patterns and the neural circuits that underlie thoughts can actually be controlled in this deliberate way. I'd like to take a quick break and thank our sponsor AG1. AG1 is an all-in-one vitamin mineral probiotic drink with adaptogens. I've been taking AG1 daily since 2012, so I'm delighted that they're sponsoring this podcast. 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For this month only, November 2024, AG1 is giving away one free month supply of omega-3 fatty acids from fish oil, in addition to the usual welcome kit of five free travel packs and a year supply of vitamin D3K2 with your order. Omega-3 fatty acids are critical for brain health, mood, cognition and much more. Again, go to drinkag1.com/huberman to claim this special offer. And then finally, there are actions. Actions or behaviors are perhaps the most important aspect to our nervous system. Because first of all, our behaviors are actually the only thing that are going to create any fossil record of our existence. After we die, the nervous system deteriorates, our skeleton will remain.