Skip to playerSkip to main contentSkip to footer
MediaEntertainment
  • 6/7/2025

Category

📺
TV
Transcript
00:00Waking up in the morning. Making your morning coffee. Recognizing friendly faces. Eating,
00:15sleeping, breathing, loving. It's easy to forget that we owe all of this to one thing. Who you
00:25are depends entirely on what's happening in your brain and we tend to think of
00:29ourselves as well there's me and I've got my personality and my sense of humor
00:32whatever and then there's my brain which is this biological organ but but in
00:36fact these are inseparable. Responsible for everything we'll ever think, know or
00:44experience our brains are completely shut off from the world we rely on them to
00:51navigate. Locked in the silence and darkness of our skulls all our brain
00:58ever experiences of the outside world arrives in the form of electrochemical
01:04signals rocketing along neurons at up to 268 miles per hour. Somehow the brain is
01:12really good at extracting patterns and assigning meaning to these patterns of
01:17activity and from that you get your entire subjective world. All the colors and
01:23the sounds and everything that's going on around you it's actually happening in
01:28darkness in there. So how does it happen? How are firestorms of electrochemical
01:35signals responsible for everything any human has ever felt, ever thought, or ever done?
01:43The journey begins with gathering data from the outside world. Fundamentally the
02:01brain is a general purpose computing device and whatever information you feed it
02:06it'll figure out the best that it can do with it. There are lots of ways to get input
02:12into the system each animal detects its own little version of what's going on. We
02:19have a word for this in science we call this the umwelt which is the German word
02:23for the surrounding world. Different animals sense different parts of their
02:29environment. We happen to have eyes and ears and nose and fingertips and so on but
02:33other animals have completely different machinery. If you're an echolocating bat you
02:38fly around in the dark and you chirp and you get back these air compression waves and
02:42that's how you can construct a three-dimensional model of the world. If
02:46you're the star-nosed mole you've got 22 appendages and you you feel with these
02:51fingers in the dark through these tunnels and that's how you can tell the
02:54three-dimensional structure of these tunnels. For each sensory organ the
03:01mechanisms are similar. Take the human eye. Light bounces off an object and hits your
03:08retina where there are two types of photoreceptor cells called rods and
03:13cones. These cells translate light into the electrochemical signals that travel to
03:20your brain along the optic nerve. Tiny hairs in your inner ear do the same for
03:27sound waves before sending them along your auditory nerves. It's up to our brains to
03:34give these cascades of signals meaning. Our brains piece together all of this
03:40information to help us navigate the world. But the human brain is not a simple
03:46computer and every brain is different. Sometimes we get dramatically different
03:53results. The way that you see reality and that I see reality might be very
03:58different. And you know when we talk about do we see red the same way probably not.
04:03Nature provides many clues that our brains may not be perceiving the full scope of
04:09reality. Dogs, cats and other animals have poor color vision compared to us
04:15humans. To them our lush world appears mostly in shades of gray with some blue and
04:22yellow mixed in. More extreme clues about the natural limits of our perception can
04:29be seen in creatures like mantis shrimp whose eyes can detect ultraviolet light.
04:35The interesting part is that presumably every animal imagines that the umwelt is the
04:41entire world out there. Just like we do with our vision and our hearing and so on we
04:44think oh I'm seeing reality but in fact we're only seeing a small slice of it. The
04:49amount of light that we see that we call visible light is actually less than a ten
04:54trillionth of the light spectrum. All the other stuff like gamma rays and x-rays and
05:00cosmic rays and cell phone conversations all that stuff is passing right through your
05:03body because you don't have specialized receptors to pick up on that. But could
05:11our brains process more types of information if only we gave it the tools? While
05:17we're pretty attached to our familiar senses like touch and taste our brains
05:21aren't nearly as picky. From the brain's point of view all it knows is it's getting
05:27these spikes of information. It sounds strange but if you think about the way a
05:32blind person passes a finger over Braille it's just these little bumps and they
05:37can come to cry or laugh at the story that they're reading it's the same thing
05:41you're essentially just feeling these this information on your skin and that gets to
05:45your brain. Neuroscientists like David Eagleman are using the brain's natural
05:51flexibility called plasticity to adapt our old senses in new ways to expand our
05:58brain's access to the world and our skin is a promising new frontier. Your skin is
06:05this incredible organ it's the largest organ of your body it covers your body but in
06:12modern life we cover it up and we don't really use it for much of anything. In my
06:17lab we've built this vest and it's covered with vibratory motors. It's just like the
06:21the buzzing motor in your cell phone except there are 32 of them. We can
06:25translate any kind of data stream into patterns of vibration all over your torso.
06:31Okay let's try four new words. One of our first subjects was a gentleman named Jonathan who was
06:45profoundly deaf and at the age of 37 he'd never heard anything in his life so there
06:50was a part of his you know possible experiential world that was just missing for him.
06:55Work. Work. Work. Play. So we put the vest on him he was he was our first subject and we
07:05trained him for a couple hours a day for four days and by the fifth day he was able
07:10to get words. Sleep. Work. We would say a word and he would feel the pattern on the vest and he would write on the board
07:24what word he thought we said. The pattern is too fast you've got 32 motors and and it's on a 16 millisecond time frame so you can't possibly get it consciously but his brain was unlocking those patterns.
07:39Work. This is called sensory substitution and hearing and seeing impaired humans have been inventing new forms of it for thousands of years.
07:50But with these new technologies the goal is not only to make sensory substitution a faster more unconscious ability but to access a broader slice of reality.
08:03For example we're expanding the sense of smell by having a molecular detector that picks up on sense and you feel that so you can tell sort of what a drug dog could feel with its long snout and its specialized sense reception.
08:17You can expand your sense by just turning that into information you have on your skin.
08:22There's really no limit on the horizon as far as how much we could expand our umwelt.
08:28Whether that's stock market data or twitter or weather data or prosthetics or smell data or whatever it is the opportunity is now open for us to feed in new senses and have a bigger and bigger understanding of the reality around us.
08:42There probably will be some limit the brain readjust its real estate depending on what's coming in but we're not up against that limit yet we could probably have several more senses and the brain would be able to understand that just fine.
08:57But even just with our old fashioned senses a lot of work goes into the relatively stable sense of reality that our brains create for us.
09:10It's hard to appreciate just how much our brains do for us because we're not even aware that most of it's happening.
09:17As it turns out that's intentional.
09:20We wouldn't be able to function if we had to have access to what's going on in the unconscious brain and that's because we are these enormous creatures made of trillions and trillions of cells and somehow this little three pound organ has to control this whole thing that's happening.
09:37Most of what we do is unconscious. Everything from lifting a cup of water to your mouth to recognizing a friend's face to falling in love to driving a car.
09:48All these things are underpinned by lightning storms of brain activity but you don't have any awareness to this or any access to this instead it just seems natural to you.
09:57Something like vision takes up about a third of the human brain but it just feels natural you open your eyes and there's the visual world.
10:04When you think about the unconscious brain you think about heartbeat and digestion and breathing and so on but it's all this other stuff too.
10:16Keeping all of the trains on track requires some masterful orchestration by our brains.
10:22Just to ensure we experience time and space as solid stable and reliable our brains actually have to create a series of illusions.
10:32What we think is that we move through the world and you see something and you immediately perceive it but in fact your brain has to gather that information and put it together and the weird part is that your different senses have different timelines for how quickly they process things.
10:48So for example vision is slower than hearing which is why you use a gun at the Olympics to start the sprinters.
10:57If I touch your face that gets registered by your brain almost immediately but if I touch your toe it takes a long time for that signal to climb all the way up your spinal cord and get to your brain.
11:06Some hundreds of milliseconds slower and yet if I touch your toe and your nose simultaneously you'll think that those are simultaneous.
11:15The brain waits for all the sensory information to come in stitches it all together and then you have this feeling that the moment now just occurred.
11:24By the time you feel that it's already happened a long time ago.
11:28We might not notice our brain shaping our perception of time on a daily basis but under extraordinary circumstances it becomes more obvious.
11:39That's what happens when time seems to slow down or even stand still.
11:46What happens is when you're in a very scary situation you've got these parts of your brain that come online that are emergency centers for when everything is hitting the fan.
11:56And you write down memory with these systems essentially on a secondary memory track.
12:02Much denser you retain everything that's going on.
12:05Your brain's only interpretation of that is oh it must have lasted longer.
12:10Because I remember the hood crumpling and the rear view mirror falling off and the look on the other guy's face.
12:15So you think wow that must have taken a really long time but it's only in retrospect that you think that.
12:22It's a trick of memory. Under normal circumstances your memory is like a sieve.
12:26You're not remembering most everything that's happening and so you've got this way of judging how much time passed.
12:32On a longer time scale this translates to what kind of new memories you're writing down.
12:39So what happens to all of us as we get older is we get into routines and when you're in routine your brain's not really writing down any memory.
12:46So you get to the end of a summer as an adult and you think back about your work and you think I don't even have that much footage to draw from.
12:53I guess nothing really happened. It seems like that whole summer disappeared quickly.
12:57In contrast when you're a child everything is new it's all novelty and so when you look back on a summer's worth of memories you have so much memory.
13:06And so it seems like it lasted longer.
13:08That tells us we need to always be seeking novelty because that's the thing that expands our lives.
13:13I can't tell you how to actually live longer but I can tell you how to make it seem as though you've lived longer.
13:18Which is by finding new things that actually write down memory.
13:23These tricks of memory aren't the only way our brains determine our reality.
13:29In fact our brain's subjective understanding of the world isn't just limited to how we experience certain events.
13:37It's hardwired into our biology itself.
13:41The fact is your brain is changing all the time depending on your levels of testosterone and your stress at this moment and what's going on and what time you woke up and so on.
13:50Your brain is changing all the time.
13:52On a long time scale we have this illusion of continuity like I'm the same person I was a year ago and ten years ago and so on.
13:58But none of that is true and in fact you're changing quite a bit through time.
14:02We can see this most clearly when our skull, the quiet calcium shell that protects our brain, is shattered.
14:11Humans can transplant organs and engineer artificial limbs without fundamentally changing who we are.
14:19But our brains are different.
14:22The brain is one thing if you damage even a little bit of it you're completely changed.
14:26The way we know that is because of all the examples of damage we see to the brain.
14:31Even if you damage your brain just a little bit that changes who you are entirely.
14:37Just as an example, Phineas Gage was a young railroad worker and there was an explosion that caused an iron rod to pass through his head.
14:45And his personality changed entirely after that happened.
14:48It became a famous medical case because he didn't die.
14:50But he became a very different person and I think that was one of the first examples in the medical literature that told us,
14:58Wow, what's happening with your biology matters about how you behave.
15:05Because of this deep connection between our brains and who we are, a better understanding of our brains won't only advance medical science.
15:16It could help us build a more sophisticated society.
15:20Brains all develop in very different ways depending on genetics and all of life experience, brains go off on very different trajectories.
15:30In reality, no two bodies are identical.
15:33And no two lives are identical.
15:35So no two brains are identical.
15:38Even given the same exact information, no two brains will process it the same exact way.
15:47This is what we value about computers is it keeps data exactly the right way.
15:52But brains are sloppier and stranger than that.
15:54They manipulate data in ways and try out new versions.
15:57And that is the basis of the whole creativity of our species.
16:03But this engine of creativity also makes it more difficult for humans to genuinely empathize with one another.
16:10It's very hard actually to put yourself in someone else's shoes.
16:14Yeah, we all try to do that all the time, but we stink at it.
16:17When we step in someone else's shoes, we're essentially taking all of our life experience and stepping there and saying,
16:22Well, I wouldn't have done that or whatever.
16:24These stubborn assumptions don't only have consequences for our personal relationships.
16:29They also lie at the heart of the United States' troubled, one-size-fits-all criminal justice system.
16:37America has the number one incarceration rate in the whole world.
16:41We put a higher percentage of our population behind bars than any other country in the world.
16:46It's very expensive and it has very low utility.
16:49What if we could use neuroscience to design a more effective, more humane system?
16:56I'll tell you where this is already taking place.
17:00When counties run out of money when they want to build another prison and they can't afford it,
17:05they start doing things that are a little bit smarter.
17:07They have a specialized drug court where the judges and juries have expertise in drug rehabilitation.
17:13And you send people down that route and you can get something done there.
17:16Specialized mental health court.
17:18So you send somebody there, judges and juries have expertise in what mental illness is and what are the rehabilitative strategies.
17:26There are different ways to route people through the system depending on what's going on with their individual brain.
17:32As our understanding of our brains and their plasticity evolves, the possibilities reach far beyond our justice system.
17:42From education, to healthcare, to technology, how well we understand our brain's world could revolutionize our ability to shape our collective outer world.
17:56The general story with the brain is it's very hard to look at it because it's locked in this bony vault that mother nature provided to protect it.
18:03And so what we have are techniques to peer inside the brain non-invasively in a living brain.
18:10But these techniques aren't that great.
18:12We're kind of missing the sweet spot.
18:15We can look at millions of neurons at once or using an electrode we can measure just a few neurons.
18:22But what we really need is to be able to measure what's happening with tens of thousands of individual neurons at once.
18:28And when we can get down to that kind of scale, then we can really make progress on understanding what are the computations that the brain is doing.
18:36It is a really exciting time in neuroscience, but I think the best is yet to come.