How Your Brain Builds Reality From Electrical Signals

A railroad blast in 1848 drove an iron rod through Phineas Gage’s brain and somehow didn’t end his life, but it did reshape who he seemed to be. That story pulls me straight into one of the strangest questions in neuroscience: if a small change in brain tissue can change personality, where does the “self” actually live? 

I take you from early misconceptions that placed thought in the heart to the evidence Hippocrates and Galen built from head injuries, then into the microscopic breakthrough of neurons and synapses. We talk about how electrical signals and chemical messengers create a living network with billions of cells, and why that network behaves less like a neat filing cabinet and more like a busy city or an orchestra. Along the way, I connect the science to everyday experiences, including blind spots you never notice, the cocktail party effect that filters noise, and the way your brain predicts what happens next. 

From there we dig into neuroplasticity and Donald Hebb’s “neurons that fire together wire together,” exploring how practice, attention, and repeated habits physically rewire the brain. We also confront the unsettling side of brain science: memory is not a perfect recording, recall is reconstruction, and researchers still can’t find a single command center where “you” sit. If you love psychology, consciousness, perception, and practical brain science, this rabbit hole is for you. 

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Phineas Gage And The Self

SPEAKER_00 0:00

In 1848, a railroad worker in Vermont was doing what he'd done a thousand times before. His name was Phineas Gage. His job was to pack explosive powder deep into solid rock using a long iron tamping rod. It was dangerous work, but he was good at it. But then in a single instant, everything went wrong. The powder exploded before it was supposed to, and the iron rod, which was over three feet long and weighed more than thirteen pounds, shot straight up like a spear. It entered beneath his left cheek, passed behind his eye, traveled through the front of his brain, and landed more than eighty feet away. By every measure that should have been the end of his story, but it wasn't. Phineas Gage stood up, spoke to the people around him, he even climbed into the wagon that carried him to the doctor. He survived. Yet, over the weeks that followed, the people who knew him began saying something a little unsettling. He still looked like Phineas Gage, he still remembered his friends, he could still walk and talk, but somehow he wasn't the same person. And that raises a question that's kind of haunted doctors and scientists ever since. If changing one small part of the brain can change who someone is, then where exactly does you live?

Why Ordinary Things Hide Secrets

SPEAKER_00 1:23

I'm Andrew Perry, and this is ADHD in the theory of all the things. Let's follow the rabbit bubble. Every episode we take something ordinary, something you've probably seen or used, maybe experienced a thousand times, and we ask a simple question. Why? Because once you start pulling on that thread, you discover that nothing is ever as simple as it seems. You'll meet the curious people who refuse to stop asking questions, uncover the history hidden in plain sight, and explore the science that quietly shapes our everyday lives. So grab a notebook if you're the note-taking type, or just bring your curiosity, because today we're following another rabbit hole.

The Brain As World Builder

SPEAKER_00 2:54

You could hold one in your hands. It's pretty soft, almost the consistency of firm tofu, gray with hints of pink, covered in folds that really kind of look random. If somebody had never seen a brain before, they probably wouldn't guess that they were looking at the most complicated object we have ever discovered. It doesn't glow, it doesn't hum or make any noise, it doesn't look powerful, and yet everything you've ever experienced has passed through it. The first face you've ever recognized, the first time you rode a bicycle, or the smell of fresh cut grass. Even the lyrics to that one song you didn't even realize you still remembered, your brain was there for all of it. The strange part is that your brain isn't just remembering the world, it's building the world that you experience. Right now, light is pouring into your eyes. Sound waves are bouncing into your ears, pressure receptors are firing in your fingertips, and temperature sensors are just reporting the room whether it feels warm or cool. None of those things are sights, sounds, or feelings. They're just electrical signals. Tiny pulses racing through billions of cells. And somehow your brain takes all of those signals and assembles them into a single experience that feels effortless. You don't notice the construction, you just experience the finished product. That's what makes the brain so difficult to understand. It doesn't just help you think about the world, it's the reason you're able to experience a world at all. But for most of our history, people had no idea that was even true. In fact, for a thousand years, I mean, they were looking in the wrong place entirely.

When The Heart Was The Mind

SPEAKER_00 5:12

Now, if you lived in ancient Egypt and asked where your thoughts come from, you probably wouldn't have pointed to your head. You would have pointed here. Well, you can't see, but to your heart. You would have pointed to your heart. To the Egyptians, the heart was the center of intelligence, memories, emotions, and even well, your soul. So when somebody died, embalmers would preserve the heart inside the body. The brain was literally removed through your nose with a bunch of funky-looking hooked tools and discarded just it was thrown off to the side. The brain didn't matter. After all, you can feel your heart race when you're scared. You can feel it pound when you're excited. You can uh I mean, well, you can't feel your brain doing anything at all. Around 400 BC, a Greek physician named Hippocrates began questioning that belief. He noticed something that others had overlooked. People who suffered injuries to the head often lost the ability to speak, move, or remember. A wound to the heart didn't erase someone's personality. A wound to the brain would. Hippocrates proposed something a little radical for his time. He believed that the brain was where we think and where we feel and where we understand the world. For him, it was an extraordinary insight. For everyone else, they thought he was an idiot. But it wasn't enough to settle the argument. Like centuries later, another physician entered the story and he kind of his name was Galen. Working in the Roman Empire during the second century, Galen treated wounded gladiators. Day after day, he saw injuries that most people never survived. Like Hippocrates, he noticed that the damage to different parts of the brain caused different problems. Like some guys couldn't speak ever again after a fight. Others couldn't move. Some lost their senses entirely. The evidence kept pointing in the same direction. The brain wasn't just another organ. It seemed to be running everything. And even then, nobody knew how. There were no there wasn't any microscopes back then. You couldn't do a CT or any kind of MRI, nothing. There was nothing for you to see, nothing for you to do. You couldn't even do any EEG. There was no electricity, there was nothing. So all you could do was just observe. And that's what they did. They would carefully observe and then they would ask another question. Now the one they've settled on is how could something so ordinary just control everything that makes us us? I mean, if you looked at it with the microscopes of the day that they had, I mean, technically, yeah, that is what it seemed to be. There were no obvious wires, there was no moving parts, you know, tiny, like tiny little machines. There was nothing. I mean, you even your bones have hinges. Like there's it's just an impossibly complicated gray pink ball.

Neurons Synapses And Endless Traffic

SPEAKER_00 8:55

So in the late 1800s, a Spanish scientist named Santiago Ramon Cayal sat down at his microscope hour after hour, day after day. He studied slices of brain tissue that were stained with a new technique they developed. It was developed by an Italian physician named Golghi. And he believed that the brain was just one continuous network. Now, Cayol saw something a little different. He noticed that the cells weren't actually connected, they were super super close to each other, like incredibly close. But there were tiny gaps that separated them. It was a revolutionary idea. Like the brain wasn't a giant web, it was made of billions and billions of individual cells. Today we call them neurons. And every thought you've ever had has depended on them talking to one another. A single neuron is not an impressive thing. On its own, it's just one tiny living cell. But your brain contains roughly 86 billion of them. Each one reaches out like branches of a tree. They form thousands of connections with their neighbors. Although the connections number in the hundreds of trillions, it's it's less like a computer than it sounds, but it's more like the busiest city anybody could imagine. Except every road is carrying messages and every interstate is making decisions. But the traffic never stops. Not when you're awake, not when you're asleep, not even when you're listening to me talk right now. Tiny electrical impulses race down neurons, triggering chemical messengers to just jump across the microscopic gaps to meet one another. The gaps are called synapses. Now the process repeats millions and millions of times every single second of your life. And somehow, out of that ridiculously endless conversation between synapses and neurons, you just get a memory. You pull a memory out of thin air. The memory of your first bike ride, the smell of rain on hot pavement, your favorite meal, or this moment right here. The more scientists uncovered about the brain, the stronger their argument was for it just being the most insane thing we've ever heard of. Because they realized your brain wasn't just being there to interpret the things you would experience. It wasn't there to just help you experience reality. In many ways, it was creating the entire reality that you were experiencing in the first place.

Blind Spots And The Cocktail Party

SPEAKER_00 12:11

Now, if I asked you whether you trust your own senses, I'm I imagine most of us would say yes. After all, they're our window to the world. You see what's in front of you, you hear what's around you, you feel what's in your hands. I mean, it's simple enough, right? Except that's not actually what's happening. Take your vision, for example. Right now, each one of your eyes has a blind spot. There is there's a place in your eyes, in each one where your optic nerve leaves the eye. There's no light detecting cells there at all. Like none. There's no cells at all. Which means there's a small hole in every single thing that you're looking at. You've never noticed it. And it's not because it's not there, but it's because your brain is filling in the missing information. It makes its best guess. And it's so good at it that you experience a complete picture. Your eyes your brain is just making up that spot. So you I mean, can you trust it? Your eyes also send your brain an upside-down image of the world, as we've talked about in the photography episode. Somewhere between your retina and your conscious experience, your brain transforms the signals brought in, like the rays of light and the colors into the world that you recognize without you ever even knowing that it's happening. I mean, you know it's happening now, but you don't you're not consciously aware of it happening. And then there's sound. Walk into a crowded restaurant. At first it feels it's overwhelming. Like there's dishes, there's music, there's a baby crying somewhere every time. But within a minute or two, your brain starts making choices. It pushes most of the noise into the background so you can focus on the person sitting across from you. Now the scientists call this the cocktail party effect. It's one reason that you can suddenly hear your own name spoken from across the across the room, from the other side of the room, even when you aren't paying attention. Have you ever had that? Where you swore, you swore someone just said your name, but you're on the other side of the room. Your brain was listening the entire time. It just decided what deserved your attention. The same thing happens with touch and smell and taste, even with time itself. Your brain isn't recording the world like a video camera. I mean, a lot of people think that. You just walk around and you're just constantly storing memories and it's like you're recording with a camera. It's it's taking incomplete information and then comparing it with everything that you've learned. And it's predicting what should happen next. It's constructing the experience that you call reality. And that sounds almost unbelievable, but it explains something that we've all experienced. Listen to this. Have you ever just swore that you saw something out of the corner of your eye and then you realized it was just a shadow? Or have you reached for one more step on a staircase that just wasn't there? Like you just you go to that last step and it's not there. You've either double-stepped or you fell down. Because your brain it wasn't broken, it wasn't messed up in that moment. It was making its best prediction based on a pattern. You've been going upstairs over and over and over and over again, and your brain just automatically assumes that's the new standard. That's what's gonna happen. Usually, you know you're at the end of the staircase, you can consciously think about getting off that step, but your brain is ready to keep going. Most of the time, your brain is ridiculously accurate. Sometimes. Sometimes it's just a little too confident, though.

Neuroplasticity And Habit Wiring

SPEAKER_00 16:26

For a long time, scientists did believe that your brain came with a deadline. Like the thinking went it was it went more along the lines of as a child, your brain grows. And then as an adult, it's done. And from that point on, you just lose brain cells a little bit at a time until you grow old. I mean, it sounds reasonable, it kind of was also wrong. In 1949, a Canadian psychologist named Donald Hebb threw up an idea that seemed a little bit too simple. So he suggested that when two neurons are active at the same time, the connection between them grows stronger. So his famous phrase became neurons that fire together wire together. At first, it was just a theory. Now, over the decades that followed that, scientists gathered more and more evidence that Hebb was kind of onto something. Your brain is not a finished machine, it's a living one. Every time you practice a skill, when you learn a new route home, or you pick a new musical instrument, or even when you hear someone's name enough times to finally remember it, your brain is changing itself. Not metaphorically either, like physically changing itself. Your connections get stronger, and some of them, some of the other ones get weaker. New pathways are forming, old ones are fading. You know, scientists they call this neuroplasticity. And it is probably one of the coolest abilities the brain has. Like it is the coolest thing your brain does. Think about uh riding a bicycle. So the first time, everything feels awkward, like you're kind of wobbly and you're thinking consciously about the handlebars and you're holding them, you're thinking about your balance and the pedals, where you're looking. It feels impossible. Like if it you if they're doing so many things at one time. But then after repetitive bike rides, over and over again of the struggle and the balance and all of that, something changes. One connection at a time, you were building a network so efficient that you don't you don't have to think about riding a bike anymore. You just ride it. The same thing happens when you learn to type, or drive a car, or tie your shoes, read, speak a language. Uh like or I mean if you re okay, so if you want to recognize the name of someone you love, or the face of someone you love, your brain is constantly rewiring itself to become a little better at what you ask it to do most often. So I mean, that also means the habits we repeat aren't just what we do, they're the things that we're teaching our brain to become. Like that realization, I mean, if you think about it and you go a little bit deeper into that, what you surround yourself with, I've told my friends and the people that I know for years. What you surround yourself with is what you become. You surround yourself and you put yourself in these situations and you expose yourself to bigger and better things, smarter things, stronger things, that's how you grow. Like you can't, if you're around okay, so take a friendship, for example. If you're friends with someone who's essentially going nowhere in life, say you know they're a bad person and they just you don't know why you're friends with them, but you just are because you just feel bad about it. But they're a bad person. They they don't have any goals, they're not gonna go anywhere in life, they're not gonna be anything. There is a likelihood based on science that your brain is going to start to develop those same tendencies. You'll tend to be lazy, you'll tend to be whatever you're around. You've heard the phrase you are what you eat. Well, I mean that's that's pretty accurate. Even over the last however long we've been talking, your brain has changed. Just a little bit. But it it changed just from listening to this. Just because you were curious enough to keep listening.

Strange Brain Facts And Memory Limits

SPEAKER_00 21:24

Uh, you because when I'm looking at this stuff and I'm going through and I'm trying to find things, there's always a few things that I can come across that just either I enjoyed reading or I thought were funny. I mean, but when you're talking about the brain and you're actually looking for research on the brain, it's really hard to decide what counts as normal and what counts as weird. Because almost every single thing that the brain does is unbelievable. Like your brain. So take this for instance your brain makes up about 2% of your body weight.

unknown 21:59

2%.

SPEAKER_00 22:01

But it uses over 20% of the oxygen and the energy of your entire body. Like you're in out of all the energy your body consumes, all of the oxygen your whole body consumes, the brain gets twenty percent. That that one thing in the top of your head gets twenty percent of all of the energy that your body consumes. It's one of the hungriest organs that you have. Nuts. I mean, it's more than your stomach. So okay, here's another one. So the brain can't feel pain. It has no pain receptors at all. None. So that's why, like during certain brain surgeries, the patient can actually be awake while the surgeon is poking around in there. Like he's stimulating different parts of the brain to make sure they're operating, you know, in the right place. They're trying to make sure that everything is doing what it's doing. So they have to have you awake to know if they've gone too far or if they're not far enough. You know what I mean? And then, okay, so now there's memory. And so one of the things that I read, I kind of talked about it a little bit earlier. Your like you might think that your brain stores memories like videos on a hard drive or on a computer. Well, it it doesn't. Every time you remember something, your brain is rebuilding the memory from just pieces that are scattered all over the place. So it puts your brain doesn't have a certain spot for a memory. Like there's a spot that controls memory, but the memories themselves just exist out in the brain somewhere. Pieces of them. Like I mean, every every memory that you have, every time you remember something, in a way, it's a new creation. Like you just made that up based off of tiny bits and pieces of what you remember. That's one reason. So that's one reason that eyewitness testimony, it's it's pretty unreliable. Like take uh take a room of 20 people and then show them one thing. You've seen this experiment a million times. Just think about it. You show a room full of 20 people one thing, you leave the room and you come back and you ask everyone to tell you what they saw, and there's a good chance that almost every single person is going to give you a slightly different version of what they saw. Now, it's not because they're lying. Like people usually aren't lying. It's their brains are just reconstructing the past as faithfully as it can. Now, your brain is incredibly fast. It can recognize a familiar face in just a fraction of a second. Way before you've even consciously thought about it. You're like, oh, oh, I know that person. Way before that, your brain has already realized they knew that person. And despite everything we've learned over the last few centuries, we're still discovering new things. Scientists are continuing to map the brains, the wiring, and just they are uncovering new cell types. And they're they just keep investigating how billions of neurons working together somehow give rise to consciousness itself. So, in other words, the most complicated object we've ever found is still full of mysteries, which feels kind of strangely appropriate because after all, the brain is using itself to solve the puzzle of itself.

No Command Center For You

SPEAKER_00 25:57

Now I'll tell you one thing that really bothered me a little bit with this. So we can explain neurons and we can explain the synapses. We can by this time we can watch electrical signals move through the brain. We can see and have all kinds of scans and MRIs and CTEs. But I mean, we well, we can even see parts like if you there are some that you can even see parts of the brain become active while somebody's talking or when they remember something or when they're having a dream. You can see which part of the brain is actively working. But none of that really answers the biggest question. Like, how does that all become you? But for centuries, scientists they search for a single place where the self might live, like a control room or command center, like some hidden corner where your personality or your memories and fears and all that stuff, where your sense of humor, where they all come together, like they merge to make this one thing. And they've never found one. Instead, they found something a little bit more fascinating, I guess. There's not one place that's you. The version of you that is listening to this right now exists because billions of neurons are constantly exchanging information. So your ability to recognize your best friend's face, it's not in one tiny spot. I mean, your favorite song's not in the tiny spot, your favorite memory. Like if you okay, so your first day of school, it's not just in one spot of your brain. Like we talked about a while ago when I was telling you about memory, the sound of your mother's voice, they're all spread across a ridiculously complex network that's always changing. It's always adapting, it's always rewriting itself. And maybe that's why the brain, like, why injuries can be weird. Like damage to one area might make somebody unable to recognize faces. Like you can have all of your memory intact, but you won't be able to recognize a face. Look at Brad Pitt. He has face blindness. Who knew? Another like another injury might you might erase the ability to speak, but but it won't inf it won't affect your intelligence at all. Like you could be the smartest person on the planet and not even able like you can't speak. The brain isn't organized the way that we would organize like a filing cabinet. It's more like an orchestra. There's no single instrument performing the entire symphony, but they all play together. And then just the show goes on. I mean, the brain isn't just an organ that lets us experience life. As I said, like in many ways, it's the reason we experience anything at all. Like every color you've ever seen, every laugh you've ever shared with anybody, every question you've ever asked, ever, every rabbit hole you've ever followed. They all began inside the little three-pound universe that you carry around on your shoulders since I mean the day you were born. And somehow it's curious enough to spend a lifetime trying to understand itself. Like the brain, like we said in the last uh last few minutes, you're your brain is the only thing that is trying to literally study itself and understand itself.

The Brain You Will Never See

SPEAKER_00 29:45

So when I first started researching the brain, and I thought this episode was going to be about neurons or electricity, and I mean it is, but I kept coming back to something a little simpler. Like we talked about it a few times. It's it's a central concept here. For your entire life, you've experienced the world through an organ you'll never actually see. Like ever. I mean, you'll see someone else's, but you'll never see yours unless you're one of those patients where the surgeon operates on your brain. And even then, I don't think they let you see. My wife wanted to see her C-section while she was having it. The doctors thought we were weird. No, we just work in the medical field, so that's kind of it's a thing. But no, they wouldn't let her see it. I mean, I guess the reasoning is there, like you don't know what you're gonna actually think whenever you see the inside of your guts and find out what's all going on in there and you see it pulled out of your body. But still, you like you'll never it's hard to explain. You'll see your own eyes in a mirror and you'll hear your own voice in a recording, and like you'll recognize your hands in a picture, and you can look at them, like you get it. But the one thing that makes all of that possible will never be seen. Ever. And it works every second of every day. It doesn't, it doesn't ask for attention. I mean, it just keeps going. It learns, it adapts, it rewrites itself. It it stores every single moment of your life, the one that makes it yours. And somehow, out of billions of tiny little tiny little conversations that are happening between the neurons in your brain, creates a whole person with dreams and fears, favorite songs, people they love, and questions. I mean, curiosity is a thing. That's the reason we're here. That might be the most incredible part of all. Your brain isn't just the most complex thing we've ever discovered, it is the only known object in the universe that is trying to understand itself.

Why Memories Survive Change

SPEAKER_00 31:55

Now, while I was researching this episode, the obvious, obvious question popped up. If your brain is constantly changing, why don't all of your memories disappear with it? Like, how can the smell of fresh cut grass instantly make you just flash back to your childhood? Like, why does one old picture unlock an entire afternoon that you hadn't thought about in years? And why do some moments stay with us forever while others just disappear before the day's even over? They're gone. That's the rabbit hole I think we're gonna follow next. We're gonna go with the story of memory. I'm sure it's gonna overlap with this one a little bit, but we're gonna dig a little bit deeper into memory itself, like the study of memory, how it operates, and the way that all of that kind of comes together. Because remembering might be even stranger than thinking. As we talked about, a lot of your memories that you think are real are pretty made up. But thank you for joining me for another rabbit hole.

Review Share And Stay Curious

SPEAKER_00 33:04

If you enjoyed today's episode, I'd love it if you guys would leave a review and share it with somebody who loves asking why. It really helps more curious people find this podcast. We've been doing pretty well, and I really thank you guys for listening. Uh, until next time, keep asking questions, stay curious, and remember, nothing is ordinary once you know the story behind it. Don't be afraid to fumble the rabbit hole.