What are mini brains? – Madeline Lancaster

This pencil-eraser-sized mass of cells
is something called a brain organoid. It’s a collection of lab-grown neurons
and other brain tissue that scientists can use to
learn about full-grown human brains. And it can be grown from
a sample of your skin cells. Why would we need such a thing? Neuroscientists face a challenge: shielded by our thick skulls and
swaddled in layers of protective tissue, the human brain is
extremely difficult to observe in action. For centuries, scientists have tried to
understand them using autopsies, animal models, and, in recent years, imaging techniques. We’ve learned a lot through
all these methods, but they have limitations. Conditions like Alzheimer’s
and schizophrenia, and the effect on
the human brain of diseases like Zika, continue to hide beyond our view,
and our understanding. Enter brain organoids,
which function like human brains but aren’t part of an organism. Each one comes from
an undifferentiated stem cell, which is a cell that
can develop into any tissue in the body, from bone to brain. Scientists can make undifferentiated
stem cells from skin cells. That means they can take a skin sample
from a person with a particular condition and generate brain organoids
from that person. The hardest part of growing
a brain organoid, which stumped scientists for years, was finding the perfect combination of
sugars, proteins, vitamins, and minerals that would induce the stem cell
to develop a neural identity. That was only discovered recently,
in 2013. The rest of the process
is surprisingly easy. A neural stem cell essentially
grows itself, similar to how a seed grows into a plant, all it needs are the brain’s equivalents
of soil, water, and sunlight. A special gel to simulate
embryonic tissue, a warm incubator set at body temperature, and a bit of motion to mimic blood flow. The stem cell grows into
a very small version of an early-developing human brain, complete with neurons that can connect
to one another and make simplified neural networks. As mini brains grow, they follow
all the steps of fetal brain development. By observing this process,
we can learn how our neurons develop, as well as how we end up with
so many more of them in our cortex, the part responsible for higher cognition
like logic and reasoning, than other species. Being able to grow brains in the lab,
even tiny ones, raises ethical questions, like: Can they think for themselves,
or develop consciousness? And the answer is no, for several reasons. A brain organoid has the same tissue types
as a full-sized brain, but isn’t organized the same way. The organoid is similar to an airplane that’s been taken apart
and reassembled at random; you could still study the wings,
the engine, and other parts, but the plane could never fly. Similarly, a brain organoid allows us
to study different types of brain tissue, but can’t think. And even if mini brains were organized
like a real brain, they still wouldn’t be able
to reason or develop consciousness. A big part of what makes our brains so
smart is their size, and mini brains have only
about 100,000 neurons compared to the 86 billion
in a full-sized brain. Scientists aren’t likely to grow larger
brain organoids anytime soon. Without blood vessels to feed them, their size is limited
to one centimeter at most. Finally, mini brains aren’t able
to interact with the outside world. We learn by interacting
with our environments: receiving inputs through our eyes, ears, and other
sensory organs, and reacting in turn. The complex neural networks that underlie
conscious thoughts and actions develop from this feedback loop. Without it, the organoids
can never form a functional network. There’s nothing quite like
the actual human brain, but mini brains are an unprecedented tool for studying everything
from development to disease. With luck, these humble
organoids can help us discover what makes the human brain unique, and maybe bring us closer
to answering the age-old question: what makes us human?

100 thoughts on “What are mini brains? – Madeline Lancaster

  1. Thank you so much to everyone who is supporting our nonprofit mission on patreon.com/teded! Check it out, if you want to know more about how you can get involved!

  2. If this advances further, then we could technically grow our own robo-humans, and then maybe an actual human.
    Yes, the narrator said these brains don't have consciousness, but if I understood correctly, that's because we can't really make them any bigger or wire them correctly. If we made a suit capable of supplying everything a normal brain would need, then we could theoretically grow a mini brain into a normal size, although it still wouldn't be wired correctly.

    However, if we managed to link up sensors that feed the brain info like our own (sight, touch, etc.), and hooked them up to the correct parts, the brain may be able to learn and realize what's around it. If we found a way to make the brains learn enough to be able to discern different objects and other such things, we could give it a robotic body and see if it begins to learn how to move around.

    Even further in the future, if this succeeds, we could try to put the brain in organic body of artificially grown limbs (Which are already a science, although it's still evolving). If we manage to do this, even if it isn't that well done, it will spell out a future of artificially grown humans, and give us the possibility to make humans with bodies that excel in certain areas; for example, we could grow limbs that are stronger and more durable than your typical human's.

    Basically, we could soon begin to grow super humans and make them fight robots for us

  3. Remember this video, kids!

    You will have to explain to your grandchildren how the Flying Brains War started

  4. This is interesting but you spent an uncomfortable amount of time trying to justify and reassure how ethical this is, I'm now more worried than I was.

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  6. but if they can't act like actual human brains how can we accurately study the diseases on these 1cm mass of neural cells .. for eg if there is no interaction with the world due lack of connections with other sense organs how is it better than studying the actual organ ??

  7. The animations in this are absolutely brilliant! I couldn't focus on the explanation the first time I watched this video (the explanation is amazing btw). I muted the video on one of my viewings just to observe the plethora of amazing graphic design and kinetic motion techniques used in this video… I love this channel because of the beautiful animations and amazing explanations! Keep up the good work.

  8. To know the answer of the age-old question , scientists must study both brain and heart. Also the brain cells in the heart.

  9. This is an interesting new format… but I feel it's too confusing for a science talk. Would have worked for something abstract like humanities

  10. I read abt stem cells bank , even ova to keep in deep freeze for making organs n test tube babies / surrogation whatever . As women want to choose careers over family . Then suddenly that stopped . Now, this .
    I feel, all this is not natural . It will require lot of money . Artificially intelligent robots will look after , and all that .
    I don't know this subject . It may be for very rich ppl . And why do they agree , is a question mark .
    I hv less faith in scientific results which keep changing with time .
    This kind of information produces unnecessary fear . Hv u seen very old movie " dr. Zivago " or coma ? Recently , robot , Ra one ? Or ET ( n similar so many movies ) . ? Looks more like psucological games to control ppl .
    These comments are like layman' s comments . Can't say if mini brains are just small small ideas of ppl .

  11. I thought this video would be about controllers for specific body parts. I recall watching a ted talk on how a crab chews using less than 100 cells(Somewhere around 100)to control the jaws.

  12. So how do we know that this "mini-brain" is that much like a real one when we know so little about the real one?

  13. I'm researching a brain in real size inside my head for 23 years while they are still researching mini-brains? Pff

  14. What if you put a brain organoid (if that's the correct spelling) in an android and let the android interact with the things you give to it and let the brain process about it? Would that be possible? Please enlighten me, I'm kinda confused.

  15. WAIT does that mean neural stem cells have been successfully cloned from a person?? So the next question is how to successfully transplant patients with neurodegenerative diseases with their own NSC, right??

  16. I love the analogy – the way the brain organoid is likened to parts of the plane. Thank you, TED-Ed!

  17. For anyone interested in learning more check out our resources on neural organoids here:



    And for those with hPSC culture experience, dive right in with this complete kit to create cerebral organoids based on the Lancaster protocol.


  18. Is there a chance that neurons in the mini brains can replace damaged ones in our own brains? I know the mini brain has limited neurons but what if that limit is all we need?

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