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  • - The final guest video in this run is from Alie and Micah,

  • a neuroscientist and a clinical therapist who run Neuro Transmissions.

  • Their video has giant magnets, 3D printing, and a Star Wars action figure.

  • Alie, Micah, it's all yours.

  • - We're here at the Keck Center at UC San Diego.

  • And this is a functional magnetic resonance imager, or an fMRI.

  • - Well, functional, but not functioning.

  • This is actually a dummy scanner

  • that's used for educational and training purposes.

  • An actual fMRI machine houses a 3-Tesla magnet

  • that's more than 60,000 times more powerful than the Earth's magnetic field.

  • And over 3,000 times more powerful than your average fridge magnet.

  • If we were anywhere near the real deal,

  • well, we would put our camera and our equipment at serious risk.

  • - But why on earth would anyone possibly need a magnet so powerful?

  • Well, some of the researchers here

  • at UCSD are using fMRI to study the human brain

  • in ways that 30 years ago just weren't even possible.

  • - I'm Maggie, I'm a fourth-year graduate student at UC San Diego.

  • - My name is Stephanie Nelli,

  • I'm a sixth-year PhD student in John Serences' lab.

  • - We study mostly selective attention and expectation and other cognitive factors

  • and how they influence visual processing in humans.

  • - My research is about really basic visual perception.

  • How do we make sense of the world around us?

  • How do we choose, out of the plethora of things

  • that are constantly accosting our visual system,

  • how does your brain make sense of the massive amount of information

  • constantly bombarding it?

  • fMRI itself was developed not very long ago,

  • it's a very new technique, as far as human research goes.

  • And it was developed in the '90s, I believe, actually in Bell Labs.

  • - fMRI is a particular specialty of MRI called functional MRI,

  • so what that does is basically, instead of measuring the difference

  • between particular tissues, you're actually optimising

  • to detect the difference between oxygenated vs. deoxygenated blood

  • in a person's brain.

  • - For a long time, it was impossible to look at the brain up close

  • without cracking open someone's skull.

  • [Micah laughs]

  • And even if you got a brain from someone who's passed on, that's not all that useful

  • for understanding how it works.

  • When Leonardo Da Vinci dissected the human brain in the 16th century

  • it was with the intention of finding the seat of the human soul.

  • Spoiler alert, he didn't.

  • - Unsurprisingly, the functions

  • of different brain areas were essentially a mystery

  • well after the scientific revolution.

  • But fMRI changed all that by giving scientists

  • the ability to see the brain working in real time,

  • track activities in different brain regions,

  • and read your mind.

  • - No, unfortunately not for us scientists, an fMRI machine cannot read the mind.

  • It can tell you basically where blood is being transported to in the brain.

  • So which parts of the brain are active.

  • - An fMRI scan can tell you when someone is doing some cognitive task,

  • what kind of patterns of brain activity you see.

  • So which areas are active, what information are those areas representing.

  • For instance, if you have someone look at different images and you measure MRI

  • while they do that, then later if you have that same person come in and you say,

  • okay, think about something.

  • Now, based on that information, I can guess what you were thinking about.

  • - I could probably say you're looking to the left

  • by looking at your neural activity

  • or I could say you're looking at a horizontal line

  • by looking at your neural activity.

  • However, am I gonna be able to tell what you're daydreaming about

  • or who you're in love with or something like that?

  • No, I don't think think that's gonna happen in my lifetime but, you know,

  • I said it on camera so we'll be able to... [laughs].

  • - It might not quite make sense how a magnet does all of this,

  • so let's break down the process step by step.

  • Let's say that Rey here has been having

  • some neurologically linked problems and a doctor refers her for an fMRI.

  • All of her Force powers are messing with her head.

  • "Oh no, Kylo Ren keeps appearing in my mind!

  • "I can't stop thinking about his hot torso.

  • "Ohhh!"

  • - The technicians place her on the table,

  • give her some earplugs and stabilise her head

  • so she can't move it at all.

  • If the head moves during the scan, the images will come out fuzzy.

  • Next, the table slides into this large, doughnut-shaped

  • section which houses the ultra-powerful magnet.

  • The strong magnetic field of this magnet

  • then actually turns the hydrogen atoms in our blood.

  • - Wait, what?

  • - Yeah, the human body has a lot of hydrogen atoms because well,

  • we're mostly made up of H₂O, that's water.

  • The magnetic field from the fMRI interacts with the protons in the hydrogen atoms

  • and makes those protons essentially point in the same direction.

  • That's right, your molecules are magnetic.

  • Hence, the magnetic resonance part

  • of magnetic resonance imaging.

  • - Once Rey's in position, she'll hear a series

  • of very loud clangs and beeps.

  • [MRI machine beeps repeatedly]

  • But these sounds aren't just the hottest new beat,

  • they actually serve a purpose.

  • Every clang you hear is a radio wave pulse being fired off.

  • This radio wave disrupts the uniform direction of the protons and pushes them

  • in slightly different directions.

  • Here's the cool part.

  • As the protons move back into realignment,

  • they release their very own small radio signal

  • and those signals are then detected

  • by the fMRI machine's radio receiver,

  • which starts taking snapshots of cross-sections of your brain,

  • which you hear as the beeping sound.

  • After some complicated computation, what shows up on the computer screen

  • is a series of images that show both

  • the anatomy of your brain and highlighted areas

  • where there's more blood flow.

  • Pretty cool, right?

  • - Yeah, so fMRI doesn't actually measure your brain activity.

  • It can't detect your individual neurons firing,

  • as cool as that would be.

  • fMRI machines actually detect what's called the BOLD signal.

  • - So the BOLD signal stands for blood-oxygen-level dependent signal

  • and it's basically an index of how much oxygenated haemoglobin

  • is in a person's blood at a particular point in their brain.

  • - Neurons themselves don't keep a high store of glucose hanging around

  • so that they can do their job and so the blood vessels,

  • through these things called astrocytes, actually,

  • help supply neurons with the glucose

  • and oxygen that they need to do their signalling.

  • - When you have neural activity that happens in your brain,

  • a bunch of blood will rush to that area

  • and it turns out that oxygenated and deoxygenated haemoglobin in your blood

  • have different magnetic properties. So deoxygenated haemoglobin

  • will disrupt the magnetic field more than oxygenated haemoglobin will

  • and it'll actually cause a decrease in the signal.

  • So when you look at an fMRI image, the higher the signal you have,

  • the more oxygen is in your blood at that point.

  • And so you actually can measure

  • with the BOLD signal after these neural events occur.

  • That basically tells you how much energy was consumed at that location.

  • - Now, it's not perfect.

  • It can't detect changes instantaneously

  • or tell you exactly what kinds of signals are being sent.

  • - But even with its limitations,

  • it lets us better understand which brain regions do what.

  • Using fMRI, scientists have been able to identify 180 distinct brain regions.

  • Better understanding the roles of different brain regions means

  • that doctors can use that information to help treat and support patients

  • with neurological disorders or brain injuries.

  • fMRI technology is cool, but both of us wanted more.

  • We wanted to get into the machine and see what our own brains looked like.

  • Maggie and Steph asked me to participate in a pilot research study looking

  • at how humans distinguish between faces and I jumped at the chance to help out.

  • - I didn't participate in the study but I was able to get a structural scan.

  • It doesn't measure blood flow

  • but it does give you a high resolution image of your brain's anatomy.

  • It was a strange experience, being inside.

  • It felt like being in a plastic coffin.

  • I can see why some people get claustrophobic.

  • - And participating in the study was harder than I expected.

  • While the task I was doing was easy,

  • it was hard to stay focused on doing

  • the same thing over and over for almost two hours.

  • But it was also really cool to see the results.

  • - And yet, we could not pass up on the opportunity of a lifetime.

  • - I mean, sure it's cool to see your brain on a screen

  • but imagine holding it in your hands.

  • What does my own unique brain really look like?

  • Well, as it turns out, we're able to find out.

  • - Thanks to modern software, we're able to take the 2D slices of our brains

  • and compose them into a 3D render

  • and print them out.

  • Cue the time lapse.

  • - Well, look at that beautiful brain.

  • - I really liked how the rainbow filament turned out on this.

  • - Yeah, it's so pretty. - This turned out really cool.

  • - I know, and I really like my glow-in-the-dark print.

  • It's super bright.

  • - The grooves are much wider in yours, and not quite as tightly packed,

  • whereas mine is super tightly folded.

  • - It's cool that you can see the inside too,

  • the hippocampus and all these different brain regions.

  • - Obviously I knew that my brain wasn't perfectly symmetrical, no one's brain is,

  • but you can really see very obvious differences.

  • It's really interesting to see, like, oh, that's my brain's shape.

  • - Right, I didn't really think about that before.

  • - Every time someone comes over to our house

  • I'll be like, did you see my brain?

  • - Lemme show you my brain. - Lemme show you my brain!

  • - It's incredible that we have the technology to track the activity

  • of a live human brain.

  • fMRI has pushed neuroscience to new heights

  • and has given us a glimpse into the seat of human consciousness.

  • And only somewhat less incredible

  • is the fact that we can use those same images

  • to build 3D models so we can create a life-size version

  • of our own brains.

  • How funny that just a chunk of squishy cells this big

  • can come up with such incredible tools

  • to help us better understand our minds and ourselves.

  • - Huge thanks to Maggie and Steph from the Serences lab for their expertise

  • and to UCSD for giving us access to their scanner.

  • And thanks to Tom for giving nerds like us the chance to share our brainy love.

  • Maybe we'll see you later?

  • - Maybe?

  • - Until next time, we're Neuro Transmissions,

  • over and out.

  • - Thank you folks, go subscribe to Neuro Transmissions.

  • I would recommend starting with Micah's video

  • on training a cat to high five

  • or Alie's video on how marijuana affects your brain.

  • And that's it! I'm back next week

  • and I will see you then.

- The final guest video in this run is from Alie and Micah,

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I Got To See And Hold My Brain (I Got To See And Hold My Brain)

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    林宜悉 に公開 2021 年 01 月 14 日
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