# What is a brain?

An episode of [Science for Kids / Science's Not Boring: The Kids Science Podcast](https://invisiblenetwork.ai/podcast/1896928296), 6 Oct 2026, 11 min.

Audio: https://www.buzzsprout.com/2624612/episodes/19879854-what-is-a-brain.mp3

Have you ever wondered what is going on inside your head? Imagine a massive, buzzing city with over a hundred trillion roads, where cars zip by at 268 miles per hour! That is exactly what your amazing brain is like! It is packed with 86 billion tiny cells called neurons that pass messages to each other at lightning speed. Join Mira and Finn as they uncover the incredible secrets of how our minds are wired! You will learn all about the tiny immune cells called microglia that act like little gardeners in your head, snipping away unused pathways so your brain can think super fast. But what happens when those gardeners work a little differently? Discover why absolutely no two brains are alike! We explore how autistic, dyslexic, and ADHD brains are wired with unique connections that give people incredible strengths—like superpower hyperfocus, rapid problem-solving, and spotting brilliant details everyone else misses. Find out why a world full of differently wired brains is exactly what humans need to invent, explore, and do amazing things!

## Transcript

[0:00] SPEAKER_00: Welcome to Sciences Not Boring by Kidopoly.com.
[0:04] SPEAKER_00: I'm Mira.
[0:05] SPEAKER_00: And I'm Finn.
[0:06] SPEAKER_00: We have a very special hello today to Elliot, who asked us about autism and why some brains are wired differently.
[0:13] SPEAKER_00: This one is for you, Elliot, and a big hello to your brother Ellis too.
[0:17] SPEAKER_01: Yeah, great pick, Elliot! If you haven't already, tap follow wherever you're listening so you never miss an episode.
[0:25] SPEAKER_00: Okay Finn, imagine a massive city at night.
[0:29] SPEAKER_00: Now, imagine if that city had a hundred trillion roads crisscrossing everywhere, and cars zipped down them at almost 270 miles per hour.
[0:40] SPEAKER_00: Whoa, what city is that?
[0:42] SPEAKER_00: Is it New York?
[0:44] SPEAKER_00: Tokyo?
[0:45] SPEAKER_00: It's not a city at all.
[0:47] SPEAKER_00: It's actually inside your head.
[0:50] SPEAKER_00: Your brain is packed with about 86 billion tiny cells called neurons.
[0:56] SPEAKER_00: 86 billion?
[0:58] SPEAKER_00: Yep, and they pass messages to each other across up to 1,000 trillion connections.
[1:05] SPEAKER_00: Today we're talking about how these connections are built and why some brains, like autistic, dyslexic, and ADHD brains, are wired entirely differently.
[1:16] SPEAKER_01: Wait, how do 86 billion cells even fit inside our heads?
[1:20] SPEAKER_01: Are they microscopic?
[1:22] SPEAKER_00: They are incredibly tiny, but these neurons have long branch-like arms that reach out to talk to other neurons.
[1:30] SPEAKER_00: The tiny gap between them, where the message jumps across, is called a synapse.
[1:35] SPEAKER_01: So a thought or a feeling is just a message jumping across a synapse?
[1:40] SPEAKER_00: Exactly! And it happens incredibly fast.
[1:43] SPEAKER_00: Nerve signals can travel up to 268 miles per hour.
[1:48] SPEAKER_00: That's faster than a Formula One race car.
[1:51] SPEAKER_01: But how do we even know all this?
[1:53] SPEAKER_01: Have scientists actually seen these billions of connections?
[1:56] SPEAKER_00: They are mapping them right now.
[1:58] SPEAKER_00: There is a massive global effort called the Human Connectome Project.
[2:03] SPEAKER_00: Scientists use gigantic MRI machines, these humongous magnetic tubes, to scan brains and draw a high-resolution map of all those pathways.
[2:14] SPEAKER_00: Like drawing a treasure map of the brain.
[2:16] SPEAKER_00: Exactly.
[2:18] SPEAKER_00: And what the Human Connectome Project has shown is that there is no single blueprint that every brain is supposed to match.
[2:26] SPEAKER_00: Every single brain is unique, wiring and rewiring itself as you grow.
[2:31] SPEAKER_01: So how does the brain actually build those roads in the first place?
[2:35] SPEAKER_01: Do we just grow more and more as we get older?
[2:38] SPEAKER_00: Actually, it's the opposite.
[2:40] SPEAKER_00: When you are a baby, your brain builds way too many roads.
[2:44] SPEAKER_00: By the time you're a toddler, you have double the number of synapses that an adult has.
[2:49] SPEAKER_01: Wait, double the connections?
[2:51] SPEAKER_01: Our heads are going to run out of room.
[2:55] SPEAKER_00: Don't worry.
[2:56] SPEAKER_00: As you grow, your brain goes through a process called synaptic pruning.
[3:00] SPEAKER_00: It's like having a crew of tiny gardeners in your brain that snip away the roads you don't use.
[3:06] SPEAKER_00: So the pathways you do use get super fast and strong.
[3:10] SPEAKER_01: Tiny gardeners?
[3:12] SPEAKER_01: What are the gardeners?
[3:13] SPEAKER_01: Do they have little shears?
[3:15] SPEAKER_00: They are special brain cells called microglia.
[3:18] SPEAKER_00: They literally roam around your brain checking connections.
[3:22] SPEAKER_00: If a pathway isn't being used, they trim it away.
[3:25] SPEAKER_01: That is so cool.
[3:27] SPEAKER_01: But what if the gardeners work differently in some people?
[3:31] SPEAKER_00: That's exactly where brain wiring gets really interesting.
[3:35] SPEAKER_00: Scientists have discovered that for autistic kids, like our friend Elliot, those microglia gardeners are a bit less aggressive.
[3:43] SPEAKER_01: Wait, so an autistic brain has extra roads left open?
[3:47] SPEAKER_00: Yes! Research from scientists at Columbia University showed that older teenagers with autism had way more synapses than teenagers without autism.
[3:57] SPEAKER_00: The pruning process works completely differently, leaving a denser network of connections.
[4:03] SPEAKER_01: Whoa! So what happens when you have all those extra connections running at full speed?
[4:08] SPEAKER_00: It means the volume knob on incoming signals is turned right up.
[4:13] SPEAKER_00: It's never an illness or a mistake.
[4:15] SPEAKER_00: It's just a different wiring pattern.
[4:18] SPEAKER_00: If you are autistic, your brain is taking in so much more information all at once.
[4:23] SPEAKER_00: Does that make things louder or brighter?
[4:26] SPEAKER_00: It can, because those extra roads are passing signals at full speed.
[4:31] SPEAKER_00: A scratchy label on a shirt or a super noisy room with lots of overlapping voices can feel genuinely painful.
[4:39] SPEAKER_00: Your brain is trying to process everything all at once without a filter.
[4:44] SPEAKER_01: Oh, I get it.
[4:46] SPEAKER_01: So if the volume is stuck on high, that's why needing a quiet break makes total sense.
[4:51] SPEAKER_00: Exactly.
[4:52] SPEAKER_00: And sometimes moving your body in a certain way, or repeating a movement called stimming, helps your brain regulate all those full-volume signals and feel calm.
[5:03] SPEAKER_01: But what about the strengths?
[5:04] SPEAKER_01: Does having a dense network of extra roads give you any special abilities?
[5:09] SPEAKER_00: Oh, absolutely.
[5:10] SPEAKER_00: Because the local connections are so strong, an autistic brain might spot the tiniest detail that everyone else just walked past.
[5:19] SPEAKER_00: Or they might experience hyper-focus.
[5:22] SPEAKER_00: Hyper focus?
[5:23] SPEAKER_00: What's that?
[5:24] SPEAKER_00: It's like having a superpower flashlight.
[5:27] SPEAKER_00: Instead of a dim glow lighting up a whole room, all your brain's energy goes into one brilliant beam.
[5:34] SPEAKER_00: A brain wired to go deep can learn literally everything there is to know about trains or outer space or engineering.
[5:42] SPEAKER_01: That sounds awesome.
[5:44] SPEAKER_01: What about other differently wired brains, like ADHD?
[5:48] SPEAKER_00: With ADHD brains, scientists think their pruning timeline might just be a bit delayed, and their brains are always looking for extra stimulation.
[5:58] SPEAKER_00: That means they can be incredibly creative and solve problems super fast because their brains jump between ideas like lightning.
[6:06] SPEAKER_00: And dyslexia.
[6:07] SPEAKER_00: I know some kids at school who are dyslexic.
[6:10] SPEAKER_00: Dyslexic brains are wired to use completely different pathways for reading.
[6:15] SPEAKER_00: They might have a harder time decoding letters, but they are often brilliant at seeing the big picture or building 3D models in their minds.
[6:23] SPEAKER_01: So it's like everyone has different ways of thinking, with different strengths, and things that are hard for them.
[6:29] SPEAKER_00: Exactly.
[6:30] SPEAKER_00: A differently wired brain isn't a problem to be fixed or cured.
[6:35] SPEAKER_00: It's just a different way of experiencing the world.
[6:38] SPEAKER_00: And honestly, we need all of them.
[6:41] SPEAKER_01: Wait, why does the world need all these different brains?
[6:45] SPEAKER_00: Because if every brain was wired exactly the same, we'd all be stuck on the exact same problems.
[6:52] SPEAKER_00: Having a world full of differently wired brains, autistic, dyslexic, ADHD, and everything else, is exactly what has helped humans invent, explore, and figure things out.
[7:05] SPEAKER_01: So we need the big picture thinkers and the super deep detail thinkers to work together.
[7:11] SPEAKER_00: You got it! Alright, are you ready for some mind-blowing facts about the brain?
[7:16] SPEAKER_00: Hit me.
[7:18] SPEAKER_00: Fact number one.
[7:19] SPEAKER_00: Those tiny gardener cells we talked about, the microglia, they are actually part of your immune system.
[7:26] SPEAKER_00: They are immune cells that moonlight as brain sculptors.
[7:30] SPEAKER_01: Immune cells doing gardening?
[7:32] SPEAKER_01: That is wild!
[7:35] SPEAKER_00: Right?
[7:36] SPEAKER_00: Fact number two.
[7:37] SPEAKER_00: We mentioned nerve signals can travel up to 268 miles per hour.
[7:43] SPEAKER_00: That means the signal travels over 120 metres every single second.
[7:50] SPEAKER_01: So if I touch a hot pan, the signal reaches my brain before I can even blink.
[7:55] SPEAKER_00: Precisely! And fact number three, the human connectome project maps are so huge, they are measured in petabytes of data.
[8:04] SPEAKER_00: Just one petabyte is a million gigabytes.
[8:08] SPEAKER_00: It would take you over 13 years of non-stop watching to finish one petabyte of high definition video.
[8:16] SPEAKER_00: Alright Finn, time for the quiz.
[8:18] SPEAKER_00: Are you ready?
[8:20] SPEAKER_00: Okay, I'm ready.
[8:21] SPEAKER_00: Bring it on.
[8:23] SPEAKER_00: First question.
[8:24] SPEAKER_00: Roughly how many connections or synapses are there in the human brain?
[8:32] SPEAKER_00: Next one.
[8:34] SPEAKER_00: What is the top speed a nerve signal can travel in miles per hour?
[8:41] SPEAKER_00: Question three.
[8:43] SPEAKER_00: What is the process called where the brain trims away unused connections?
[8:50] SPEAKER_00: Here's number four.
[8:52] SPEAKER_00: What is the name of the special immune cells that act like tiny gardeners in the brain?
[9:01] SPEAKER_00: Last question.
[9:03] SPEAKER_00: What is the name of the giant science project trying to map all the brain's wiring?
[9:12] SPEAKER_00: Great job! Let's see how you did.
[9:15] SPEAKER_00: The first answer is there are up to 1,000 trillion connections.
[9:20] SPEAKER_00: For question two, nerve signals can travel up to 268 miles per hour.
[9:27] SPEAKER_00: Number three, the answer is synaptic pruning.
[9:31] SPEAKER_00: Question 4.
[9:33] SPEAKER_00: Those tiny gardeners are called microglia.
[9:36] SPEAKER_00: And the final answer is the Human Connectome Project.
[9:40] SPEAKER_01: You know, learning how brains are wired makes me want to be a better friend.
[9:45] SPEAKER_01: If someone needs a quiet space, it's just because their brain's volume is turned up.
[9:50] SPEAKER_00: That is the perfect way to look at it, Finn.
[9:53] SPEAKER_00: Understanding the science helps us understand each other so much better.
[9:58] SPEAKER_01: Hey, if you love learning about the brain's tiny gardeners, please leave us a five-star review.
[10:04] SPEAKER_00: Yes, just scroll down and tap the stars.
[10:07] SPEAKER_00: And make sure you tap follow on this show and check out our sister shows too.
[10:12] SPEAKER_00: History and philosophy is not boring, and maths is not boring.
[10:16] SPEAKER_00: Go give those a listen and a follow as well.
[10:18] SPEAKER_01: And if you want to shout out on the show or just want to say hi, email us at hello at kidopoly.com.
[10:26] SPEAKER_00: Thanks for exploring the brain with us.
[10:28] SPEAKER_00: See you next time on Science is Not Boring.
[10:31] SPEAKER_00: Bye, everyone.

Shows are listed from Apple Podcasts' charts and directory, and Podcast Index where it is used. Every show and episode belongs to its publisher and plays from the publisher's own feed; this site hosts none of them.