September 29, 2020 • 40 mins
What does our growing understanding of neuroplasticity reveal about our brains and the future of technology? In this episode of Stuff to Blow Your Mind, Robert chats with neuroscientist David Eagleman about his new book “Livewired: The Inside Story of the Ever-Changing Brain.”
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Speaker 1 (00:03):
Welcome to Scoot to Blow Your Mind production of My
Heart Radio. Hey, welcome to Stuff to Blow Your Mind.
My name is Robert Lamb. Joe is away from work.
He's realigning his gray matter at the moment, so it's
just me today, but I'll be joined by neuroscientist, author,
(00:24):
and science communicator David Eagelman about his new book Live Wired,
The Inside Story of the Ever Changing Brain. Now we've
mentioned David Eagelman on the show many times before. He's
an adjunct professor at Stanford University and his CEO of
Neo Sensory, a company that develops devices for sensory substitution.
You may also know him from his previous books about
(00:46):
the human brain, his TV series The Brain with David Eagleman,
and his role as a scientific advisor on HBO's Westworld,
and the t NT series Perception. I'm recording this on
a Monday, and I actually read Live Wired over the weekend.
It's a highly addictive read and one that I think
our listeners will will really enjoy. David does an amazing
job breaking down the inner workings of the brain via
(01:08):
relatable pop culture and historical metaphors. Everything from the Colonization
of the America's to Mr Potato Head and Ellen Ripley
from Aliens. It's published by Pantheon Books and you can
currently grab it as a hardcover, an e book, or
an audio book. And the fun thing is that that
David reads the audio book. It's always great when you
when you get that with an audio book. So, without
(01:31):
without any further ado, let's jump right in. David Eagleman,
thanks for joining me today. Great to be here, Robert.
First of all, I have I just have to say
that this book was such an engaging read. Actually read
it all over the weekend, and while I was familiar
with some of the findings and technologies discussed, there was
plenty I hadn't been exposed to yet, and it was
(01:51):
all delivered in such a fashion that it all ended
up feeling like, you know, it's kind of like a revelation. Um,
and I feel like that revelation is really well summarized
in the title of the book, live Wired. If you would,
could you summarize the basic difference between the idea of
the live wired understanding of our brain as opposed to
previous notions of how the brain worked. Yeah, I mean
(02:14):
the whole The whole thing is that when you first
pick up a neuroscience textbook as a young person, you
see a picture of the brain and it says this
parts or visions, parts are hearing, the parts are touch,
and so on. But in fact, UM, I guess what
I've spent the last twenty years, you know, in my
laboratory really understanding the lesson of is that the brain
is a is a dynamic system that's constantly moving around.
(02:37):
And so, for example, if you go blind, the part
that we would have called your visual system gets taken
over by hearing and touch. If you lose an arm,
the part of your body map that has an arm
gets taken over by neighboring areas, and so on. The
whole thing is this incredibly dynamic system. It's not like
anything that we know how to build. Um. You know,
here in Silicon Valley where I live, everything is about
(02:58):
hardware and software, and engineers are praised for building an
efficient system where you've got these two layers and that's it, um.
But what's happening in our skulls is an entirely different
kind of technology. And so I in the book, I
ended up coining a new term for this live Wired
or live where. And the idea with live where is
(03:20):
that every moment of your life, this is reconfiguring itself.
So you've got eighty six billion neurons, these are the
cell types in the brain. You've got about point two
quadrillion connections, and every moment in your life, these things
are changing their strength of connection. They're unplugging, they're replugging elsewhere,
they're seeking around. What you have are these dense jungles.
(03:46):
And you know, this level of complexity is something that
bankrupts our language. We don't have any way of talking
about point two quadrillion connections moving and changing. But everything
in your life, every experience that you have, UM changes
who you are. When you learn, for example, that my
name is David, there's a physical change in the structure
of your brain. And that's what it means for you
(04:07):
to then remember, you know, two months later, who's the
guy you had on your podcast David. You know, it's
like it's it's this constantly changing system and it's UM
unlike anything that we know how to build at the moment.
So UM you know, as you as you saw in
the book, I tell these different stories just by way
of introduction that are so fascinating, Like you can take
(04:30):
out half the brain in a child. For example, when
children have this really bad type of epilepsy, there's a
surgery that they go through. Half the brain is removed,
and they're just fine cognitively, they're totally fine because the
rest of their brain, the other half says, Okay, I'm
gonna rewire the functions that are that went missing from there.
Sometimes a child is born with only half a brain,
(04:52):
you know, and things just get get rewired so that
it all is there and we can't you know, you
can't do this with your cell phone or your computer.
You can't take out half the circuitry and expect it
to still function. But it works just fine, especially with
a young brain. Now, with all of this in mind,
into this live wired understanding of the brain in mind, um,
(05:14):
I thought we might back up to a very basic question. Uh.
Sometimes I guess we don't think about because we're I mean,
we were trapped in the brain. We can't see the
forest for the trees. But what what does the brain do?
So the brain is locked in silence and darkness inside
the vault of your skull, and all it's trying to
do is make a model of the world, as in,
(05:35):
I've got all this incoming data. And by the way,
the data that comes into the brain is just spikes,
just little electrical spikes, and these neurons. It doesn't know
that these spikes represent photons, and these spikes represent air
compression waves, and these spikes represent mixtures of molecules hitting
a membrane and so on. All it knows is I've
got data coming in as zeroes and ones and um
(05:58):
and it knows that it can can troll a body.
And so it's job is to figure out, all right,
how do I control the body? How does that change
the spikes coming in? And how do I make a
model of the world. And this is an extraordinary technology
that we have carrying around on our shoulders. Um, As
I said, we we don't know how to build technology
(06:19):
like this, and we're just scratching the surface of even
trying to figure this out. But that's what the brain
is doing, locked in its in its vault, is figuring out, Okay,
how do I understand the world. And and it's really
extraordinarily good at at extracting patterns and eventually making predictions
and um, yeah, that is that is the main job
that is trying to accomplish. Now, the big part of
(06:41):
the book deals with how our senses, uh you know,
speak to the brain and how the brain works around
limitations uh such as that are the ones you mentioned
with the half of the brain being missing at etcetera.
And also uh you know relating limbs uh and uh
and I love how use these various metaphors to explain
that to the reader. Would you mind explaining to our
(07:01):
listeners how our brains are, like Mr potato Head. Yeah,
So this is something that struck me many years ago
where I realized that, so we've got all these sensors
like our eyes and our ears and our nose and
our fingertips. All these things were used to and so
we just sort of think of these as fundamental. But
but when you look across the animal kingdom, what you
find are all these other weird kinds of sensors, things
(07:23):
that you could take in like snakes taken infrared information,
honey bees taken ultra violet. When you look at something
like the black Ghost knifefish, it has electro receptors where
it's pulling in information about perturbations and electrical fields. Um.
Lots of birds and cows and insects have magneto reception
(07:44):
where they are picking up on the magnetic field of
the planet and they're navigating that way and so on.
And what I realized is Mother Nature doesn't actually have
to recreate the brain every time she does this. Instead,
the principles of brain operation, she's figured that out at
the beginning in ing, and then she can just plug
in anything she wants in terms of what is the
(08:04):
information that would be useful to sense. And that's why
I suggested this potato head model of how to think
about this, which is to say, you just take any
sensors and you stick it in and it's good to go.
The brain figures out, Okay, I've got this kind of
spikes coming in um, and it seems to correlate with
this other sense, and it seems to allow me to
find food or avoid predators or whatever. And so it
(08:27):
just figures out what to do with that information. And
so this is a very new kind of way to
think about the brain. It's essentially understanding the brain as
a general purpose compute device. You feed in whatever kind
of data stream you want, and it's and it's good
to go. And this, you know, explains a lot of
what happens evolutionarily with genetics. It just what it allows
(08:47):
Mother Nature to do is just tweak around with the
genetics to make new kinds of sensors. But one of
the really amazing things you you discussed in this is
that is that you can plug an eye into an
ear hole or an ear into an eye hole on
the Mr Potato head of our of our brain, and
the brain will roll with the data that that's exactly right.
And so this is an area called sensory substitution, which
(09:11):
is to say, you can feed information into the brain
via an unusual channel. And so something I started in
my lab about ten years ago was seeing if we
could build sensory substitution for people who are deaf. So
what we do. We started by building this as a
vest with vibratory motors in it. So you've got a
whole bunch of little buzzers like the buzzer in your
(09:33):
cell phone, and um, it captures sound and turns out
into patterns of vibration on the torso. And it turns
out that that worked really well. We could get people
who are profoundly deaf to start understanding what is happening
in the auditory world just predicated on this spatio temporal
pattern of vibrations on their skin. And the reason it
(09:55):
worked is because it doesn't matter how the information gets
to the brain. As long as it gets there, the
rain will establish the correlations and figure out what to
do with it. So, as an example, if you see,
you know, the dog's mouth moving and you feel the
buzzing on your skin, you know, your brain puts that
together really easily. Or you know, you see somebody speaking,
or or we train people by showing a word and
you you know, you feel the world on the vest
(10:16):
and you start understanding what's going on. So what we
did then is we shrunk it down to the size
of a wrist band. And because you and I are
on video, Robert, you can see the wrist band that
I'm wearing right now. It's you know, it looks about
the size of a fitbit and it has very sophisticated
computation in here where it's capturing sound and turning that
into patterns vibration around the skin of the wrist. And um,
(10:40):
so what we've been doing is we uh this Actually
now I spun a company out of my lab called
neosensory and we have been on the market since March
and we're now on wrists all around the world. So
people who are deaf for have hearing loss of some
degree where this and they are picking up on the
auditory world through their skin. Now, the interesting part is
(11:03):
this is exactly what the inner ear is doing. Your
inner ear is just registering vibrations of your ear drum
and it breaks sound up into from high to low frequency,
and then it ships it off to the brain. And
all we're doing is transferring the inner ear to to
the wrist and it works. So that's the idea of
sensory substitution. Is your um just getting the information there
(11:26):
via a different route and the brain figures out what
to do with it. And if this weren't amazing enough,
there's this then this this other additional step, this idea
of of plugging all new things into it, like new
forms of sensory information, new even uh, you know, not
only limbs of replacement, but artificial additional limbs. Use the
(11:46):
example of doctor Octopus from the spider Man comics. Um,
can you tell us a little bit about how even
like this nineteen sixties sci fi concept is not that
far removed from our current understanding of the brain. Yeah,
so um, let me actually let me say two things. Actually,
one is what we can do, so let me just
(12:08):
separate out sensory information coming in and motor information going out.
So sensory information coming in. One of the things we're
doing with the with our wristband called buzz Um is
we can not only take in sound information for people
who are deaf, but we could actually expand the sensory
information that you would normally have. So for example, with
somebody who's not deaf, we feed in ultra violet or
(12:30):
infrared or or things like that, where we're expanding senses
that you already have. And then we're doing this other
thing called sensory addition, where we're feeding in brand new
senses that you've never had. So we can feed in
any day to stream with this, like stock market data
or Twitter data or factory information or anything at all.
Feeding this in and as long as your brain can
(12:51):
make correlations with what it's seeing or hearing around it,
then the brain can figure out how to utilize that information.
So we actually just finished a big developer contest where
people did all kinds of projects with you know um
monitoring air quality or monitoring you know, blood sugar and
your bloodstream or um. Um many many different kinds of
(13:13):
monitoring of feeling, electrical fields and so on. UM. So
all this, by the way, if if anybody is interested,
we have an open a p I and an s
d K four buzz. You can get this on neo
central dot com and pursue any kind of project you
want this way. So we've had hundreds of people just
making their own thing, which has been which has been
very cool. Now to switch to the second thing about
(13:34):
motor output. UM, Yeah, it turns out that your brain
UM is not pre programmed to drive your body, but
instead can figure out whatever the affordances are of whatever
is there. So just as an example, you know, one
of the things I tell the story about this dog
UM that was born without four limbs. It didn't have
(13:55):
his front legs, and so it just she walked bipetally.
She walks on her back legs like a human and
presumably any dog could do this, but they're not sufficiently motivated,
but so she just walks around her hind legs and UM.
What this illustrates is that dog brains are not pre
programmed to drive dog bodies, but instead they figure out, Okay,
here's what I can do. I need to get to
my food, to my water, to my mother whatever. This
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is how I do it. And so um. Also, I
you know, tell the story of the guy who's the
world's best archer. He has the world's record for best
archery shot, and he doesn't have arms, so he does
this with his legs. And it's just another illustration that
the brain figures out whatever body it's in says okay,
I figure how to drive this. Of course, we see
this when people, for example, get an amputation. Let's say
(14:38):
they lose an arm in a motorcycle, accent or something.
The map of their body in their brain readjusts to say, Okay,
I see I've got a body without an arm, so
I'm just gonna figure that out now. Okay. So, because
it is not pre programmed, it's extremely flexible. Um. I
(14:59):
think that we could actually build any kind of body
we want. So um, coming back to your question, I
you know mentioned about Doc Cock in the nineteen sixties,
which debuted in spider Man, the scientist who plugs in
four robotic arms so that he can actually do extra
things and poor beakers and so on, and he controls
(15:20):
us with his brain. But then there's an explosion his
lab and he turns evil and he scales buildings and
learns new forms of martial arts with with eight arms
and so on, and um, Dr Octavia starts to go
by Doc Dock. Anyway, UM, the exactly as you said,
This is not as far off and weird as we
used to think, because now what we're doing is with
for example, patients who are paralyzed. Um, you can put
(15:44):
electrodes into their motor cortex and they can learn to
drive a robotic arm even though they are paralyzed. They
drive the robotic arm with their thoughts, which sounds weird,
but that's of course, how you drive your fleshy arm.
You just you know, you think about it, you learned
the you learned what the put signals are that make
your arm respond. It's the same thing with the robotic arm,
and you can do that. And there have been experiments
(16:05):
with monkeys where they their bodies work fine, they're not paralyzed,
but they can drive a third arm with you know,
with their thoughts. So they're driving a robotic arm with
their thoughts. There was an experiment done where a monkey
um uses his motor cortex to make a robot walk.
But the interesting part was the robot happened to be
(16:25):
across the world. The monkey was in North Carolina and
the robot was in Japan, and the signals from the
monkey's brain were being sent over the internet. And you
can get the robot, you know, the monkey to control
the robot just with the spikes in its motor cortex.
And so, UM, I think it's going to be no
time at all before we really start controlling external devices
(16:48):
with our thoughts. And one of the things, one of
the frameworks that I build is this issue that what
we think of as the self, what you think of
as your body, just as a matter of control, what
can you control with your body? And I think this
is by the way, why we understand our reflections in
a mirror to be us. Because you move in it moves,
and so you're driving what you're seeing over there, so
(17:12):
you think, oh, yeah, that's me over there. Um. But
what this means is in you know, make up a
number thirty five years, when we are controlling a robot
with our thoughts, it is essentially an extension of our body.
What it means is that that will become us. It
will be a part of of your body. All right,
(17:33):
we're going to take a quick break, but I'll be
right back with David Eagleman. Thank alright, I'm back with
David Eagleman. In the book, you talk about the live
wired brain as as being a place of competition, um,
based on the input that's coming in. And I was
just really uh intrigued by this, this new theory of
(17:56):
dreaming that you discuss. Would you would you mind h
sharing that with our listeners. Yeah, um, yeah, this is
something very cool that's come out of our studies of plasticity,
and UM here it is. It's that when any part
of the brain goes unused, it gets taken over. And
so for example, if you go blind, your systems for
(18:18):
hearing and touch and all of that real estate will
take over the part of the brain that we used
to call the visual cortex. So the surprise in neuroscience
has been how rapidly this happens. Um. What group found
about thirteen years ago was that if you take sighted
people and you blindfold them tightly and you stick them
in a brain scanner, within about an hour you can
(18:40):
start seeing activity in the visual cortex just based on
um hearing or touch. If you touch them on the
hand or something, you start seeing activation in the visual cortex. Now,
it's not because the neurons have had a chance to
grow that fast from hearing and touch into the visual cortex. Instead,
there's all kinds of cross wiring the brain where those
(19:01):
systems are already reaching over into the visual cortex. It's
just that they're normally silenced and they're inhibited, so they
don't get to do anything. But that inhibition starts wearing
off very quickly. And so I was really shocked by
the speed at which hearing and touch could take over.
And so my student and I were talking about this
one day, and what we realized is there's a very
critical thing that happens because we live on a planet
(19:23):
that rotates into darkness for half the time. You know,
in the dark you can still hear and touch and
taste and smell and all that just fine, but you
can't see. And of course I'm talking about evolutionary time,
not recent electricity times. And so um, what this means
is that the visual cortex has always been in a
big disadvantage when the planet rotates into darkness. And so
(19:44):
what we realized is, Wow, if it doesn't want to
get taken over by the other senses, it has to
have some way of defending its territory. And what we
realized was that that's what dreams are. You have this
very specific circuitry that starts in the midbrain and goes
through a series of depths and just blasts activity into
the visual cortex every night about every ninety minutes, and
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and that's its only job. It's just blast activity in there.
It's very specialized circuitry. It's very specific of the type
of thing that to the ananimouss eye is not accidental.
And so and of course, because it's our visual cortex,
we you know, we see and we think, oh, I'm
having this full, rich visual experience. Um. And of course
(20:26):
dream content might have to do with you know, it
certainly has to do with what you've experienced during the
day in which synapses are still hot and so on.
But but the point is that it's just blasting activity
in there to defend the visual system against takeover. And
so we've now done big studies on this. For example,
where I'll just give you one thing that we just
published recently where we compared twenty five different species of
(20:49):
primates and we looked at how plastic they were, because
across even the primate kingdom, you have this um you know,
spectrum of how plastic you drop into the world and
then how much rems sleep they get in other words,
how much you know, rapid eye movement or or dream sleep,
because this is when dreams happen. And it turns out
that the more plastic you are as a species, the
(21:09):
more dream sleep you have because you need to defend
it more. As opposed to the other end of the spectrum.
And say, lemurs drop into the world and they're pretty
much fully baked um and they have very short you know,
adolescents time and walking time and weaning time and all
that stuff. Um, they don't have much dream sleep because
they don't need it because their brain is sort of
baked into place. And by the way, I'll just mention
(21:30):
one other thing because people sometimes ask about this, which
is um you know, they say, do blind people dream? Yes,
blind people have dreams where activity is getting shot into
their occipital lobe at the back of their head. But
because they are blind, they don't experience that is vision. Instead,
they experience. It is hearing and touch. So blind people's
dreams are all about you know, weird bizarre things just
(21:53):
like ours, but it's not involving vision. It's you know,
I'm I'm walking around the house and all my furniture
is rearranged and I'm feeling stuff, and then there's a
air and I'm feeling the bear and all that kind
of stuff. So um, but it's exactly the same circuitry
that they have, because this is a very fundamental circuitry
that has burned into the system. And it doesn't care
whether your eyes are working or not, because it's it's more,
(22:13):
it's deeper than that, and has working on this has
has changed the way you reflect on your own dreams
at all. You know, I've always actually felt that dreams
are not terribly meaningful like my own. You know, I
wake up. I've always described this as sort of sticking
your head in the night blender each night. I kind
of hate trede Um, But now I have a deeper
appreciation for why I'm going through that night blender because um,
(22:38):
if not, I would wake up in my visual system
would be really disadvantaged. It would be taken over in
large part by hearing it by touch. Especially in the
later portions of the book, you you get into two
memories and and even identity, and there's there's a lot
that really seems to resonate with the state of the
world right now. How do you feel this book speaks
to the reader? Yeah, I think there. I think there
(23:00):
are many ways. Um I'll mention too. One is actually,
let me start with this optimistic one, which is um
as lousy as has been for everybody. And you know,
this is a year where there's serious spikes for everybody
in stress, anxiety, depression. It's just there's all kinds of
bad stuff. But I will mention one tiny silver lining
(23:23):
of this is that, from the point of view of
brain plasticity, we've all been kicked off of our hamster
wheels and we're all being forced to rethink many things
that we never thought about before. So I mentioned before
that our brain is locked in silence and darkness, is
trying to make an internal model of the world out there,
and we all pretty much had that. We thought, Okay,
(23:45):
I get how the world works, I get how things operate,
how people respond, how to get toilet paper, how to
get food in my fridge, stuff like that, and all
of a sudden everything changed. And from the point of
view of brain plasticity, this is actually really useful. It
has forced a kind of creativity, an unwanted one for sure,
but it's forced kind of creativity where you're having to
(24:07):
rethink everything. We're having to understand many things in more
depth that we never thought twice about before. And um
it turns out when we look at things like you know, dementia,
what happens is people retire and they stop challenging themselves,
and their brains end up in a worse and worse state.
And the people who retire and end up fine and
(24:29):
much better off are those who keep challenging themselves with
novel things. And that includes even basic things like just
you know, making sure you're not just sitting around watching TV,
but instead, you know, taking on new sorts of challenges
and tasks and keeping an active social life and stuff
like that. So anyway, this is what's happening to all
of us. And I have a slight suspicion this will
be hard to prove, but just an intuition that we
(24:52):
may find a slight dip in dementia UM in in
the coming years. For people who have been you have
lived through this early twenties, um, simply because they've really
gotten a chance to build all kinds of new roadways
in their brain, whereas they might not have done that
as as adults. The second thing that I'll mention as
far as is one of the things that my lab
(25:14):
has been studying for a very long time is social neuroscience,
which is this issue of how there's a lot of
the brain circuitry that's devoted to other people. In other words,
you know, we normally look at the brain and we
think already there's hearing, these touchows, vision and so on,
But in fact, a lot of your circuitry has to
do with modeling other people. And you might know a
thousand people and you've actually got circuitry devoted to every
(25:36):
one of them, and circuitry devoted to okay, who knows
who and have they dated before and blah blah blah.
I mean, it's it's a very sophisicated social system that
we're carrying around. And so one of the things that
got me interested a long time ago, and we've published
and written on this for years, but suddenly it really
is important. Is this issue about in groups and out groups,
and it turns out that, um we here, I'll just
(25:57):
tell you really quickly about a study we did. We
take people into the brain scanner and we show them
six hands on a screen, and the computer goes around
and selects one of the hands at random, and then
you see that hand get stabbed with a syringe needle.
And what happens is you really cringe when you see that.
It's it's awful to see somebody's hand get stabblished with
(26:17):
a needle. And that activates this network in your brain
that summarized as the pain matrix, which is to say,
you're you're such a feeling the pain of that. Um
that is the neural basis of empathy. You care about
somebody else because you're immediately running a simulation of what
if that was my hand, even though it's not physically
your hand getting touched. But what we do then is
(26:39):
we put a one word label on each of these
hands Christian, Jewish, Muslim, Atheist, Hindu, scientologist, and then the
computer goes around and picks a hand and see the
hand gets stabbed. And the question is do you care?
Does your brain care as much if it's someone in
your out group versus a member of your in group,
And that's exactly what happens. If it's a member of
(27:00):
your in group, you have a much bigger response, and
if it's remember of your outgroup, your brain doesn't really
care that much. And it turns out that we do
all kinds of versions of this. Just as one example,
we then say, okay, the year is twenty five, and
these three religions have teamed up against these three religions,
and now your two allies you care slightly more than
(27:22):
you did a minute ago, just because you're told in
this one sense thing that that they're allied with you,
and the others are still clearly in your outgroups. So
your brain just doesn't care as much. And by the way,
just as a side note, atheists have exactly the same
thing about seeing atheist hands get stud So it's not
an indictment of religion. It's just an issue about in
groups and out groups who you feel like you know
what your labels are. UM. So we've done a lot
(27:45):
of work on that. If anyone's interested, I wrote in
uh an article in The Economist last year called does
your brain care about other people? It depends um, But
all of a sudden in. Unfortunately, all of this stuff
is more relevant because society is really finding ways to
divide themselves up with in groups and now groups. Um.
(28:06):
You know, some people blame social media. The fact is,
you know, I'm a real student of history, and the
fact is that we've had this kind of stuff happened
all the time, with the Chinese Cultural Revolution or the
Russian Revolution or you know, or what happened in Nazi
Germany or we we've we've seen this stuff lots of
times before the Internet. So it's not like the Internet.
Is this the single thing to blame here, This is
(28:27):
just human nature. Um. So anyway, this is what I
think is relevant to Alright, we're gonna take one more break,
but I'll be right back with David Eagleman. Thank alright,
I'm back with David Eagleman. So well, let's let's take
a brief journey into the future here again coming back
(28:47):
to the idea of neural technology in the future allowing
us to augment our senses our bodies. If you, let's
say you were to enter a state of suspended animation
and emerge a hundred years from now, how much of
the human sensory experience will have changed, and how different,
How difficult do you think it would be for a
twenty second century human to relate these senses to you? Yeah,
(29:12):
I think I think this is a key issue, which
is to say, we have certain what are called quality
of which is, you know, our internal experience of something
like vision and hearing and so on. And you know,
obviously the stuff is completely made up by our brains
in the sense that just as example, colors don't exist
in the world. All you have is different wavelength of
electromagnetic radiation. But your brain comes up with a way
(29:34):
of summarizing things quickly, so it can see the ripe
fruit against the green leaves. It says, okay, I'm gonna
call that red that green perfect um, even though that
doesn't exist. So we have this internal experience of the world.
And of course, you know, sound also doesn't exist as such,
You've just got air compression waves, but we turn it
into you know, beautiful voices in music and so on. Um. Okay,
(29:57):
But here's the thing. It's because your brain has lots
of experience with this that it eventually turns it into
this direct perceptual experience. And so the question is, now,
if you fed in a new kind of data stream
through the neo century buzz, for example, the wristband. If
you fed in a completely new kind of thing, would
you come to have a direct perceptual experience of it?
(30:20):
And our data right now suggests yes, that that you would.
And the thing that's so weird about this is there's
actually no way to describe it to somebody who has
not had that experience. So imagine that you had a
friend who is color blind and you tried to explain
orange to your friend. There's no way that she would understand.
She could eventually pretend and say, okay, Robert just quit
(30:42):
talking and I'm gonna pretend I understand, but she wouldn't
ever understand orange nous. Why because you have to experience
it to get it and so um. And you know,
if you have a blind friend, try to explain what
vision is your friends, I don't understand. You're you're trying
to You're you're capturing folte that you're capturing millions of
photons of second from across great distances, and there's just
(31:04):
no way that they can understand what that's like. And
so the same thing applies, I think for twenty second
century people who are getting direct data streams fed to
their brain of stock market or microwave data information or
um you know, gamma ray information or whatever the thing
is that they're feeding in. You're like the person who
(31:26):
doesn't understand what orange is or what vision is to them.
And they can try really hard to explain to you,
and you can even pretend at some point they understand,
but you you just won't. And UM, So I think
we're on the verge of a really interesting moment in
history where where we're gonna essentially start speciating, as in,
people are going to have such different experiences that they
(31:47):
won't be able to relate them to each other. Now,
let me just say there's a sense in which this
is no different from what we've always had in the
sense that you know, you grew up in your hometown
and had your experience. I grew up my hometown and
had my experiences. Then there's a sense in which brains
are very different anyway. Um, but this is just going
to be more of that where I'm you know, plugged
directly into Twitter, and you're plugged directly into infrared information
(32:09):
and we just can't quite get what the other person
is experiencing. So you worked as a science advisor on
HBO's Westworld. That's right, that's right, um. And you know,
one of the things that I've found in advising for
television in general is that there are all these topics
that I and my colleagues have debated for years, were
(32:30):
you know, for example, the question of could robot become
conscious and what would that mean? And would they have
free will? And so on? Um, and you know, we
write all these academic papers on it, but it's it's
such a cool opportunity to get these questions to, you know,
into the public square with fiction. And so something like
West World is tremendously successful into getting people to think
(32:52):
about these sorts of questions. And one of the things
that I did as scientific advisor was, UM, got our
vest or neosensory vest into the show. So you know,
it was I don't know if anybody out there I
saw this episode during season two, but um, these military
contractors drop into west World to take care of the hosts,
(33:13):
the bad robots, and they are feeling on their vest
their location of the robots. So there's location over there there. Sorry,
there's a there's robbot over there. There's one over there
and then they can shoot them accordingly. But we've actually
used exactly that. For people who are blind, we've used
the same idea, which is they're wearing the vest and
they're feeling where people are around them, and oh, there's
somebody coming up behind me, there's someone over here on
(33:33):
my left, and so on, and then we can add
navigation directions on top of that. Um you know, so
it buzzes okay, go four, oh go, the left now
goes straight and so on. Um. So yeah, that was
a very cool, very cool opportunity that we had to
get our technology into this futuristic show. I love that
sequence in the show because I felt like like a
lesser show would have just copied Aliens and just had
(33:55):
you know, blips on a map. Uh And but this
felt this this fell thoroughly science fictional in nature, you know.
I mean, but then a GO course is using actual
technology that we're developing today. Exactly right now. You mentioned
West World bringing scientific topics or just topics concerning things
like consciousness out into the public square. The first season
(34:16):
at least discussed Julian James b cameral mind hypothesis or
brought that up a little bit and I know you
wrote about this a little bit in Incognito, but what
are your general thoughts on this hypothesis. You know, what's
interesting is that no one actually knows if it's correct
or not correct. So what Julian James proposed is that
it may be that you essentially have two sides to
(34:39):
the brain, the left and the right side, literally the
two hemispheres, and that those used to be more separate
and um, so it was as though people were hearing
a voice from somebody else. And what he argues is
that if you look at ancient literature, like ancient Greek
literature and so on, there's always this thing about hearing
a voice from God and so on. Um. And the
argument is that very recently the left and right hemisphere
(35:02):
started connecting in a deeper way. Um, and so there
was this super highway of fibers that goes back and
forth between them. And so what we have now is
a unified consciousness instead of two separate voices going on
in our heads. As I said, nobody really knows that
this is right or not, because there's no simple way
to test this directly. What I argued an incognito, though,
(35:25):
is essentially a a distant cousin of that, which is
that What is absolutely clear is that we are not
a single thing. So we think of ourselves as individuals,
meaning not divisible into different parts. But but in fact
who you are is a collection of different neural networks
that all have different drives. And this is why we
can argue with ourselves and custed ourselves in contract with ourselves,
(35:48):
and canjole ourselves who's talking with whom? Here? It's all us,
but it's different parts of us. So this is why
if I take some warm chocolate chip cookies out of
the oven and put them in front of you, part
of your brain says, don't need your get fat, and
part of brain says that looks like a high energy sort.
You know, I totally want to eat those cookies. And
part of your brain says, okay, how about I eat
the cookies, but I'll go to the gym tonight or whatever.
(36:10):
Like everything that we do in our lives, we have
arguments with ourselves about okay, what should I do here?
Part of me want to eat, this part of me
doesn't want to, And so what's going on? There are
all the different voices, the different political parties of this
neural parliament that we have running under the hood. And
this is the framework that I built in an incognito,
is that we've got this parliament and the way you
(36:31):
go just depends on the majority vote in any given moment,
and so you're not one thing, You're a collection of voters.
All right. I have one one last question for you. Um,
if if you could go back in time and serve
as a science advisor on any past science fiction film,
what would it be. What would you most like to
go back and tweak or correct or make a little
(36:53):
more neuroscientifically interesting. Oh gosh, I have to think about
that off the top of my head. Um. Something like
the Matrix is terrific, because that's an example actually of
of a piece of fiction that got everybody talking about
this issue of how do you know? Like you know,
(37:14):
Descartes said, how would I know if I'm a brain
in a vat um and and I just think that
I'm feeling and hearing and seeing these different things, And
that that got upgraded that question by philosophers um at
different stages in history. But but essentially that's the question
is how do I how do I know? If there's
a bunch of scientists that are zapping my brain with
(37:34):
electrodes that are making me feel that I'm talking with
you on zoom, and the weather is nice outside and
so on. But then the matrix, I think, singlehandedly upgraded
that question too. How do I know if I'm in
the matrix if I am a simulation? And and as
things have gone on, especially in the last I don't
know ten years in Silicon Valley, it feels like people
talk about that question more and more seriously all the
(37:56):
time because you look at our computational capacity and you think, well,
it's it's really not that hard to make super sophisticated
VR in So what's this gonna look like in one twenty?
I mean, you could make something that is absolutely convincing.
I mean, forget it. You can do that. It's just
like a convincing So the question is, how would you
know if you exist in a simulation or not? And
(38:17):
what they cart concluded, by the way, is that there
is no way for him to know um, And this
is what led to his very famous declaration japon suit
I think therefore I am um, because what he meant
by that is, look, I don't know if I'm in
a simulation, but all I can tell you is that
(38:38):
there's somebody thinking about this question. So I exist, whoever, whoever,
whatever situation I'm actually and it doesn't matter. There's some
I that exists, and that was actually a quite important
move in philosophy. But the point is, we have absolutely
no way of knowing if we are in a simulation
or not. And uh, we don't even have any good
(38:58):
hypotheses about how we would be able to find that out.
And by the way, it might not matter. I mean,
you know, if I told you with certainty that we
are or are not, it would it might not change
anything about what you're doing. Um so, But so I
would love to have been involved in in that movie
and and add in just a few neuroscience e uh
twists and sentences and questions there. Awesome, David, thanks again
(39:22):
for chatting with me today. Great, Thank you, Robert. This
is blessed all right, So there you have it again.
The book is Live Wired, The Inside Story of the
Ever Changing Brain by David Eagleman. It's out now and
if you want to check out Neosensory, you can just
go to neo sensory dot com. If you'd like to
(39:42):
listen to other episodes of Stuff to Blow Your Mind.
You can find us wherever you get your podcast and
wherever that happens to be. We just asked that you rate,
review and subscribe. Thanks as always to Seth Nicholas Johnson
for his recording skills and editing skills and bringing all
this together especially short to turn around Today. And if
you would like to eat ellis about this interview, about
this episode, or about forthcoming episodes or past episodes, you
(40:05):
can do so at contact at Stuff to Blow your
Mind dot com. Stuff to Blow your Mind is production
of I Heart Radio. For more podcasts for my heart Radio,
visit the iHeart Radio app, Apple Podcasts, or wherever you
listening to your favorite shows
Welcome to Scoot to Blow Your Mind production of My
Heart Radio. Hey, welcome to Stuff to Blow Your Mind.
My name is Robert Lamb. Joe is away from work.
He's realigning his gray matter at the moment, so it's
just me today, but I'll be joined by neuroscientist, author,
(00:24):
and science communicator David Eagelman about his new book Live Wired,
The Inside Story of the Ever Changing Brain. Now we've
mentioned David Eagelman on the show many times before. He's
an adjunct professor at Stanford University and his CEO of
Neo Sensory, a company that develops devices for sensory substitution.
You may also know him from his previous books about
(00:46):
the human brain, his TV series The Brain with David Eagleman,
and his role as a scientific advisor on HBO's Westworld,
and the t NT series Perception. I'm recording this on
a Monday, and I actually read Live Wired over the weekend.
It's a highly addictive read and one that I think
our listeners will will really enjoy. David does an amazing
job breaking down the inner workings of the brain via
(01:08):
relatable pop culture and historical metaphors. Everything from the Colonization
of the America's to Mr Potato Head and Ellen Ripley
from Aliens. It's published by Pantheon Books and you can
currently grab it as a hardcover, an e book, or
an audio book. And the fun thing is that that
David reads the audio book. It's always great when you
when you get that with an audio book. So, without
(01:31):
without any further ado, let's jump right in. David Eagleman,
thanks for joining me today. Great to be here, Robert.
First of all, I have I just have to say
that this book was such an engaging read. Actually read
it all over the weekend, and while I was familiar
with some of the findings and technologies discussed, there was
plenty I hadn't been exposed to yet, and it was
(01:51):
all delivered in such a fashion that it all ended
up feeling like, you know, it's kind of like a revelation. Um,
and I feel like that revelation is really well summarized
in the title of the book, live Wired. If you would,
could you summarize the basic difference between the idea of
the live wired understanding of our brain as opposed to
previous notions of how the brain worked. Yeah, I mean
(02:14):
the whole The whole thing is that when you first
pick up a neuroscience textbook as a young person, you
see a picture of the brain and it says this
parts or visions, parts are hearing, the parts are touch,
and so on. But in fact, UM, I guess what
I've spent the last twenty years, you know, in my
laboratory really understanding the lesson of is that the brain
is a is a dynamic system that's constantly moving around.
(02:37):
And so, for example, if you go blind, the part
that we would have called your visual system gets taken
over by hearing and touch. If you lose an arm,
the part of your body map that has an arm
gets taken over by neighboring areas, and so on. The
whole thing is this incredibly dynamic system. It's not like
anything that we know how to build. Um. You know,
here in Silicon Valley where I live, everything is about
(02:58):
hardware and software, and engineers are praised for building an
efficient system where you've got these two layers and that's it, um.
But what's happening in our skulls is an entirely different
kind of technology. And so I in the book, I
ended up coining a new term for this live Wired
or live where. And the idea with live where is
(03:20):
that every moment of your life, this is reconfiguring itself.
So you've got eighty six billion neurons, these are the
cell types in the brain. You've got about point two
quadrillion connections, and every moment in your life, these things
are changing their strength of connection. They're unplugging, they're replugging elsewhere,
they're seeking around. What you have are these dense jungles.
(03:46):
And you know, this level of complexity is something that
bankrupts our language. We don't have any way of talking
about point two quadrillion connections moving and changing. But everything
in your life, every experience that you have, UM changes
who you are. When you learn, for example, that my
name is David, there's a physical change in the structure
of your brain. And that's what it means for you
(04:07):
to then remember, you know, two months later, who's the
guy you had on your podcast David. You know, it's
like it's it's this constantly changing system and it's UM
unlike anything that we know how to build at the moment.
So UM you know, as you as you saw in
the book, I tell these different stories just by way
of introduction that are so fascinating, Like you can take
(04:30):
out half the brain in a child. For example, when
children have this really bad type of epilepsy, there's a
surgery that they go through. Half the brain is removed,
and they're just fine cognitively, they're totally fine because the
rest of their brain, the other half says, Okay, I'm
gonna rewire the functions that are that went missing from there.
Sometimes a child is born with only half a brain,
(04:52):
you know, and things just get get rewired so that
it all is there and we can't you know, you
can't do this with your cell phone or your computer.
You can't take out half the circuitry and expect it
to still function. But it works just fine, especially with
a young brain. Now, with all of this in mind,
into this live wired understanding of the brain in mind, um,
(05:14):
I thought we might back up to a very basic question. Uh.
Sometimes I guess we don't think about because we're I mean,
we were trapped in the brain. We can't see the
forest for the trees. But what what does the brain do?
So the brain is locked in silence and darkness inside
the vault of your skull, and all it's trying to
do is make a model of the world, as in,
(05:35):
I've got all this incoming data. And by the way,
the data that comes into the brain is just spikes,
just little electrical spikes, and these neurons. It doesn't know
that these spikes represent photons, and these spikes represent air
compression waves, and these spikes represent mixtures of molecules hitting
a membrane and so on. All it knows is I've
got data coming in as zeroes and ones and um
(05:58):
and it knows that it can can troll a body.
And so it's job is to figure out, all right,
how do I control the body? How does that change
the spikes coming in? And how do I make a
model of the world. And this is an extraordinary technology
that we have carrying around on our shoulders. Um, As
I said, we we don't know how to build technology
(06:19):
like this, and we're just scratching the surface of even
trying to figure this out. But that's what the brain
is doing, locked in its in its vault, is figuring out, Okay,
how do I understand the world. And and it's really
extraordinarily good at at extracting patterns and eventually making predictions
and um, yeah, that is that is the main job
that is trying to accomplish. Now, the big part of
(06:41):
the book deals with how our senses, uh you know,
speak to the brain and how the brain works around
limitations uh such as that are the ones you mentioned
with the half of the brain being missing at etcetera.
And also uh you know relating limbs uh and uh
and I love how use these various metaphors to explain
that to the reader. Would you mind explaining to our
(07:01):
listeners how our brains are, like Mr potato Head. Yeah,
So this is something that struck me many years ago
where I realized that, so we've got all these sensors
like our eyes and our ears and our nose and
our fingertips. All these things were used to and so
we just sort of think of these as fundamental. But
but when you look across the animal kingdom, what you
find are all these other weird kinds of sensors, things
(07:23):
that you could take in like snakes taken infrared information,
honey bees taken ultra violet. When you look at something
like the black Ghost knifefish, it has electro receptors where
it's pulling in information about perturbations and electrical fields. Um.
Lots of birds and cows and insects have magneto reception
(07:44):
where they are picking up on the magnetic field of
the planet and they're navigating that way and so on.
And what I realized is Mother Nature doesn't actually have
to recreate the brain every time she does this. Instead,
the principles of brain operation, she's figured that out at
the beginning in ing, and then she can just plug
in anything she wants in terms of what is the
(08:04):
information that would be useful to sense. And that's why
I suggested this potato head model of how to think
about this, which is to say, you just take any
sensors and you stick it in and it's good to go.
The brain figures out, Okay, I've got this kind of
spikes coming in um, and it seems to correlate with
this other sense, and it seems to allow me to
find food or avoid predators or whatever. And so it
(08:27):
just figures out what to do with that information. And
so this is a very new kind of way to
think about the brain. It's essentially understanding the brain as
a general purpose compute device. You feed in whatever kind
of data stream you want, and it's and it's good
to go. And this, you know, explains a lot of
what happens evolutionarily with genetics. It just what it allows
(08:47):
Mother Nature to do is just tweak around with the
genetics to make new kinds of sensors. But one of
the really amazing things you you discussed in this is
that is that you can plug an eye into an
ear hole or an ear into an eye hole on
the Mr Potato head of our of our brain, and
the brain will roll with the data that that's exactly right.
And so this is an area called sensory substitution, which
(09:11):
is to say, you can feed information into the brain
via an unusual channel. And so something I started in
my lab about ten years ago was seeing if we
could build sensory substitution for people who are deaf. So
what we do. We started by building this as a
vest with vibratory motors in it. So you've got a
whole bunch of little buzzers like the buzzer in your
(09:33):
cell phone, and um, it captures sound and turns out
into patterns of vibration on the torso. And it turns
out that that worked really well. We could get people
who are profoundly deaf to start understanding what is happening
in the auditory world just predicated on this spatio temporal
pattern of vibrations on their skin. And the reason it
(09:55):
worked is because it doesn't matter how the information gets
to the brain. As long as it gets there, the
rain will establish the correlations and figure out what to
do with it. So, as an example, if you see,
you know, the dog's mouth moving and you feel the
buzzing on your skin, you know, your brain puts that
together really easily. Or you know, you see somebody speaking,
or or we train people by showing a word and
you you know, you feel the world on the vest
(10:16):
and you start understanding what's going on. So what we
did then is we shrunk it down to the size
of a wrist band. And because you and I are
on video, Robert, you can see the wrist band that
I'm wearing right now. It's you know, it looks about
the size of a fitbit and it has very sophisticated
computation in here where it's capturing sound and turning that
into patterns vibration around the skin of the wrist. And um,
(10:40):
so what we've been doing is we uh this Actually
now I spun a company out of my lab called
neosensory and we have been on the market since March
and we're now on wrists all around the world. So
people who are deaf for have hearing loss of some
degree where this and they are picking up on the
auditory world through their skin. Now, the interesting part is
(11:03):
this is exactly what the inner ear is doing. Your
inner ear is just registering vibrations of your ear drum
and it breaks sound up into from high to low frequency,
and then it ships it off to the brain. And
all we're doing is transferring the inner ear to to
the wrist and it works. So that's the idea of
sensory substitution. Is your um just getting the information there
(11:26):
via a different route and the brain figures out what
to do with it. And if this weren't amazing enough,
there's this then this this other additional step, this idea
of of plugging all new things into it, like new
forms of sensory information, new even uh, you know, not
only limbs of replacement, but artificial additional limbs. Use the
(11:46):
example of doctor Octopus from the spider Man comics. Um,
can you tell us a little bit about how even
like this nineteen sixties sci fi concept is not that
far removed from our current understanding of the brain. Yeah,
so um, let me actually let me say two things. Actually,
one is what we can do, so let me just
(12:08):
separate out sensory information coming in and motor information going out.
So sensory information coming in. One of the things we're
doing with the with our wristband called buzz Um is
we can not only take in sound information for people
who are deaf, but we could actually expand the sensory
information that you would normally have. So for example, with
somebody who's not deaf, we feed in ultra violet or
(12:30):
infrared or or things like that, where we're expanding senses
that you already have. And then we're doing this other
thing called sensory addition, where we're feeding in brand new
senses that you've never had. So we can feed in
any day to stream with this, like stock market data
or Twitter data or factory information or anything at all.
Feeding this in and as long as your brain can
(12:51):
make correlations with what it's seeing or hearing around it,
then the brain can figure out how to utilize that information.
So we actually just finished a big developer contest where
people did all kinds of projects with you know um
monitoring air quality or monitoring you know, blood sugar and
your bloodstream or um. Um many many different kinds of
(13:13):
monitoring of feeling, electrical fields and so on. UM. So
all this, by the way, if if anybody is interested,
we have an open a p I and an s
d K four buzz. You can get this on neo
central dot com and pursue any kind of project you
want this way. So we've had hundreds of people just
making their own thing, which has been which has been
very cool. Now to switch to the second thing about
(13:34):
motor output. UM, Yeah, it turns out that your brain
UM is not pre programmed to drive your body, but
instead can figure out whatever the affordances are of whatever
is there. So just as an example, you know, one
of the things I tell the story about this dog
UM that was born without four limbs. It didn't have
(13:55):
his front legs, and so it just she walked bipetally.
She walks on her back legs like a human and
presumably any dog could do this, but they're not sufficiently motivated,
but so she just walks around her hind legs and UM.
What this illustrates is that dog brains are not pre
programmed to drive dog bodies, but instead they figure out, Okay,
here's what I can do. I need to get to
my food, to my water, to my mother whatever. This
(14:16):
is how I do it. And so um. Also, I
you know, tell the story of the guy who's the
world's best archer. He has the world's record for best
archery shot, and he doesn't have arms, so he does
this with his legs. And it's just another illustration that
the brain figures out whatever body it's in says okay,
I figure how to drive this. Of course, we see
this when people, for example, get an amputation. Let's say
(14:38):
they lose an arm in a motorcycle, accent or something.
The map of their body in their brain readjusts to say, Okay,
I see I've got a body without an arm, so
I'm just gonna figure that out now. Okay. So, because
it is not pre programmed, it's extremely flexible. Um. I
(14:59):
think that we could actually build any kind of body
we want. So um, coming back to your question, I
you know mentioned about Doc Cock in the nineteen sixties,
which debuted in spider Man, the scientist who plugs in
four robotic arms so that he can actually do extra
things and poor beakers and so on, and he controls
(15:20):
us with his brain. But then there's an explosion his
lab and he turns evil and he scales buildings and
learns new forms of martial arts with with eight arms
and so on, and um, Dr Octavia starts to go
by Doc Dock. Anyway, UM, the exactly as you said,
This is not as far off and weird as we
used to think, because now what we're doing is with
for example, patients who are paralyzed. Um, you can put
(15:44):
electrodes into their motor cortex and they can learn to
drive a robotic arm even though they are paralyzed. They
drive the robotic arm with their thoughts, which sounds weird,
but that's of course, how you drive your fleshy arm.
You just you know, you think about it, you learned
the you learned what the put signals are that make
your arm respond. It's the same thing with the robotic arm,
and you can do that. And there have been experiments
(16:05):
with monkeys where they their bodies work fine, they're not paralyzed,
but they can drive a third arm with you know,
with their thoughts. So they're driving a robotic arm with
their thoughts. There was an experiment done where a monkey
um uses his motor cortex to make a robot walk.
But the interesting part was the robot happened to be
(16:25):
across the world. The monkey was in North Carolina and
the robot was in Japan, and the signals from the
monkey's brain were being sent over the internet. And you
can get the robot, you know, the monkey to control
the robot just with the spikes in its motor cortex.
And so, UM, I think it's going to be no
time at all before we really start controlling external devices
(16:48):
with our thoughts. And one of the things, one of
the frameworks that I build is this issue that what
we think of as the self, what you think of
as your body, just as a matter of control, what
can you control with your body? And I think this
is by the way, why we understand our reflections in
a mirror to be us. Because you move in it moves,
and so you're driving what you're seeing over there, so
(17:12):
you think, oh, yeah, that's me over there. Um. But
what this means is in you know, make up a
number thirty five years, when we are controlling a robot
with our thoughts, it is essentially an extension of our body.
What it means is that that will become us. It
will be a part of of your body. All right,
(17:33):
we're going to take a quick break, but I'll be
right back with David Eagleman. Thank alright, I'm back with
David Eagleman. In the book, you talk about the live
wired brain as as being a place of competition, um,
based on the input that's coming in. And I was
just really uh intrigued by this, this new theory of
(17:56):
dreaming that you discuss. Would you would you mind h
sharing that with our listeners. Yeah, um, yeah, this is
something very cool that's come out of our studies of plasticity,
and UM here it is. It's that when any part
of the brain goes unused, it gets taken over. And
so for example, if you go blind, your systems for
(18:18):
hearing and touch and all of that real estate will
take over the part of the brain that we used
to call the visual cortex. So the surprise in neuroscience
has been how rapidly this happens. Um. What group found
about thirteen years ago was that if you take sighted
people and you blindfold them tightly and you stick them
in a brain scanner, within about an hour you can
(18:40):
start seeing activity in the visual cortex just based on
um hearing or touch. If you touch them on the
hand or something, you start seeing activation in the visual cortex. Now,
it's not because the neurons have had a chance to
grow that fast from hearing and touch into the visual cortex. Instead,
there's all kinds of cross wiring the brain where those
(19:01):
systems are already reaching over into the visual cortex. It's
just that they're normally silenced and they're inhibited, so they
don't get to do anything. But that inhibition starts wearing
off very quickly. And so I was really shocked by
the speed at which hearing and touch could take over.
And so my student and I were talking about this
one day, and what we realized is there's a very
critical thing that happens because we live on a planet
(19:23):
that rotates into darkness for half the time. You know,
in the dark you can still hear and touch and
taste and smell and all that just fine, but you
can't see. And of course I'm talking about evolutionary time,
not recent electricity times. And so um, what this means
is that the visual cortex has always been in a
big disadvantage when the planet rotates into darkness. And so
(19:44):
what we realized is, Wow, if it doesn't want to
get taken over by the other senses, it has to
have some way of defending its territory. And what we
realized was that that's what dreams are. You have this
very specific circuitry that starts in the midbrain and goes
through a series of depths and just blasts activity into
the visual cortex every night about every ninety minutes, and
(20:06):
and that's its only job. It's just blast activity in there.
It's very specialized circuitry. It's very specific of the type
of thing that to the ananimouss eye is not accidental.
And so and of course, because it's our visual cortex,
we you know, we see and we think, oh, I'm
having this full, rich visual experience. Um. And of course
(20:26):
dream content might have to do with you know, it
certainly has to do with what you've experienced during the
day in which synapses are still hot and so on.
But but the point is that it's just blasting activity
in there to defend the visual system against takeover. And
so we've now done big studies on this. For example,
where I'll just give you one thing that we just
published recently where we compared twenty five different species of
(20:49):
primates and we looked at how plastic they were, because
across even the primate kingdom, you have this um you know,
spectrum of how plastic you drop into the world and
then how much rems sleep they get in other words,
how much you know, rapid eye movement or or dream sleep,
because this is when dreams happen. And it turns out
that the more plastic you are as a species, the
(21:09):
more dream sleep you have because you need to defend
it more. As opposed to the other end of the spectrum.
And say, lemurs drop into the world and they're pretty
much fully baked um and they have very short you know,
adolescents time and walking time and weaning time and all
that stuff. Um, they don't have much dream sleep because
they don't need it because their brain is sort of
baked into place. And by the way, I'll just mention
(21:30):
one other thing because people sometimes ask about this, which
is um you know, they say, do blind people dream? Yes,
blind people have dreams where activity is getting shot into
their occipital lobe at the back of their head. But
because they are blind, they don't experience that is vision. Instead,
they experience. It is hearing and touch. So blind people's
dreams are all about you know, weird bizarre things just
(21:53):
like ours, but it's not involving vision. It's you know,
I'm I'm walking around the house and all my furniture
is rearranged and I'm feeling stuff, and then there's a
air and I'm feeling the bear and all that kind
of stuff. So um, but it's exactly the same circuitry
that they have, because this is a very fundamental circuitry
that has burned into the system. And it doesn't care
whether your eyes are working or not, because it's it's more,
(22:13):
it's deeper than that, and has working on this has
has changed the way you reflect on your own dreams
at all. You know, I've always actually felt that dreams
are not terribly meaningful like my own. You know, I
wake up. I've always described this as sort of sticking
your head in the night blender each night. I kind
of hate trede Um, But now I have a deeper
appreciation for why I'm going through that night blender because um,
(22:38):
if not, I would wake up in my visual system
would be really disadvantaged. It would be taken over in
large part by hearing it by touch. Especially in the
later portions of the book, you you get into two
memories and and even identity, and there's there's a lot
that really seems to resonate with the state of the
world right now. How do you feel this book speaks
to the reader? Yeah, I think there. I think there
(23:00):
are many ways. Um I'll mention too. One is actually,
let me start with this optimistic one, which is um
as lousy as has been for everybody. And you know,
this is a year where there's serious spikes for everybody
in stress, anxiety, depression. It's just there's all kinds of
bad stuff. But I will mention one tiny silver lining
(23:23):
of this is that, from the point of view of
brain plasticity, we've all been kicked off of our hamster
wheels and we're all being forced to rethink many things
that we never thought about before. So I mentioned before
that our brain is locked in silence and darkness, is
trying to make an internal model of the world out there,
and we all pretty much had that. We thought, Okay,
(23:45):
I get how the world works, I get how things operate,
how people respond, how to get toilet paper, how to
get food in my fridge, stuff like that, and all
of a sudden everything changed. And from the point of
view of brain plasticity, this is actually really useful. It
has forced a kind of creativity, an unwanted one for sure,
but it's forced kind of creativity where you're having to
(24:07):
rethink everything. We're having to understand many things in more
depth that we never thought twice about before. And um
it turns out when we look at things like you know, dementia,
what happens is people retire and they stop challenging themselves,
and their brains end up in a worse and worse state.
And the people who retire and end up fine and
(24:29):
much better off are those who keep challenging themselves with
novel things. And that includes even basic things like just
you know, making sure you're not just sitting around watching TV,
but instead, you know, taking on new sorts of challenges
and tasks and keeping an active social life and stuff
like that. So anyway, this is what's happening to all
of us. And I have a slight suspicion this will
be hard to prove, but just an intuition that we
(24:52):
may find a slight dip in dementia UM in in
the coming years. For people who have been you have
lived through this early twenties, um, simply because they've really
gotten a chance to build all kinds of new roadways
in their brain, whereas they might not have done that
as as adults. The second thing that I'll mention as
far as is one of the things that my lab
(25:14):
has been studying for a very long time is social neuroscience,
which is this issue of how there's a lot of
the brain circuitry that's devoted to other people. In other words,
you know, we normally look at the brain and we
think already there's hearing, these touchows, vision and so on,
But in fact, a lot of your circuitry has to
do with modeling other people. And you might know a
thousand people and you've actually got circuitry devoted to every
(25:36):
one of them, and circuitry devoted to okay, who knows
who and have they dated before and blah blah blah.
I mean, it's it's a very sophisicated social system that
we're carrying around. And so one of the things that
got me interested a long time ago, and we've published
and written on this for years, but suddenly it really
is important. Is this issue about in groups and out groups,
and it turns out that, um we here, I'll just
(25:57):
tell you really quickly about a study we did. We
take people into the brain scanner and we show them
six hands on a screen, and the computer goes around
and selects one of the hands at random, and then
you see that hand get stabbed with a syringe needle.
And what happens is you really cringe when you see that.
It's it's awful to see somebody's hand get stabblished with
(26:17):
a needle. And that activates this network in your brain
that summarized as the pain matrix, which is to say,
you're you're such a feeling the pain of that. Um
that is the neural basis of empathy. You care about
somebody else because you're immediately running a simulation of what
if that was my hand, even though it's not physically
your hand getting touched. But what we do then is
(26:39):
we put a one word label on each of these
hands Christian, Jewish, Muslim, Atheist, Hindu, scientologist, and then the
computer goes around and picks a hand and see the
hand gets stabbed. And the question is do you care?
Does your brain care as much if it's someone in
your out group versus a member of your in group,
And that's exactly what happens. If it's a member of
(27:00):
your in group, you have a much bigger response, and
if it's remember of your outgroup, your brain doesn't really
care that much. And it turns out that we do
all kinds of versions of this. Just as one example,
we then say, okay, the year is twenty five, and
these three religions have teamed up against these three religions,
and now your two allies you care slightly more than
(27:22):
you did a minute ago, just because you're told in
this one sense thing that that they're allied with you,
and the others are still clearly in your outgroups. So
your brain just doesn't care as much. And by the way,
just as a side note, atheists have exactly the same
thing about seeing atheist hands get stud So it's not
an indictment of religion. It's just an issue about in
groups and out groups who you feel like you know
what your labels are. UM. So we've done a lot
(27:45):
of work on that. If anyone's interested, I wrote in
uh an article in The Economist last year called does
your brain care about other people? It depends um, But
all of a sudden in. Unfortunately, all of this stuff
is more relevant because society is really finding ways to
divide themselves up with in groups and now groups. Um.
(28:06):
You know, some people blame social media. The fact is,
you know, I'm a real student of history, and the
fact is that we've had this kind of stuff happened
all the time, with the Chinese Cultural Revolution or the
Russian Revolution or you know, or what happened in Nazi
Germany or we we've we've seen this stuff lots of
times before the Internet. So it's not like the Internet.
Is this the single thing to blame here, This is
(28:27):
just human nature. Um. So anyway, this is what I
think is relevant to Alright, we're gonna take one more break,
but I'll be right back with David Eagleman. Thank alright,
I'm back with David Eagleman. So well, let's let's take
a brief journey into the future here again coming back
(28:47):
to the idea of neural technology in the future allowing
us to augment our senses our bodies. If you, let's
say you were to enter a state of suspended animation
and emerge a hundred years from now, how much of
the human sensory experience will have changed, and how different,
How difficult do you think it would be for a
twenty second century human to relate these senses to you? Yeah,
(29:12):
I think I think this is a key issue, which
is to say, we have certain what are called quality
of which is, you know, our internal experience of something
like vision and hearing and so on. And you know,
obviously the stuff is completely made up by our brains
in the sense that just as example, colors don't exist
in the world. All you have is different wavelength of
electromagnetic radiation. But your brain comes up with a way
(29:34):
of summarizing things quickly, so it can see the ripe
fruit against the green leaves. It says, okay, I'm gonna
call that red that green perfect um, even though that
doesn't exist. So we have this internal experience of the world.
And of course, you know, sound also doesn't exist as such,
You've just got air compression waves, but we turn it
into you know, beautiful voices in music and so on. Um. Okay,
(29:57):
But here's the thing. It's because your brain has lots
of experience with this that it eventually turns it into
this direct perceptual experience. And so the question is, now,
if you fed in a new kind of data stream
through the neo century buzz, for example, the wristband. If
you fed in a completely new kind of thing, would
you come to have a direct perceptual experience of it?
(30:20):
And our data right now suggests yes, that that you would.
And the thing that's so weird about this is there's
actually no way to describe it to somebody who has
not had that experience. So imagine that you had a
friend who is color blind and you tried to explain
orange to your friend. There's no way that she would understand.
She could eventually pretend and say, okay, Robert just quit
(30:42):
talking and I'm gonna pretend I understand, but she wouldn't
ever understand orange nous. Why because you have to experience
it to get it and so um. And you know,
if you have a blind friend, try to explain what
vision is your friends, I don't understand. You're you're trying
to You're you're capturing folte that you're capturing millions of
photons of second from across great distances, and there's just
(31:04):
no way that they can understand what that's like. And
so the same thing applies, I think for twenty second
century people who are getting direct data streams fed to
their brain of stock market or microwave data information or
um you know, gamma ray information or whatever the thing
is that they're feeding in. You're like the person who
(31:26):
doesn't understand what orange is or what vision is to them.
And they can try really hard to explain to you,
and you can even pretend at some point they understand,
but you you just won't. And UM, So I think
we're on the verge of a really interesting moment in
history where where we're gonna essentially start speciating, as in,
people are going to have such different experiences that they
(31:47):
won't be able to relate them to each other. Now,
let me just say there's a sense in which this
is no different from what we've always had in the
sense that you know, you grew up in your hometown
and had your experience. I grew up my hometown and
had my experiences. Then there's a sense in which brains
are very different anyway. Um, but this is just going
to be more of that where I'm you know, plugged
directly into Twitter, and you're plugged directly into infrared information
(32:09):
and we just can't quite get what the other person
is experiencing. So you worked as a science advisor on
HBO's Westworld. That's right, that's right, um. And you know,
one of the things that I've found in advising for
television in general is that there are all these topics
that I and my colleagues have debated for years, were
(32:30):
you know, for example, the question of could robot become
conscious and what would that mean? And would they have
free will? And so on? Um, and you know, we
write all these academic papers on it, but it's it's
such a cool opportunity to get these questions to, you know,
into the public square with fiction. And so something like
West World is tremendously successful into getting people to think
(32:52):
about these sorts of questions. And one of the things
that I did as scientific advisor was, UM, got our
vest or neosensory vest into the show. So you know,
it was I don't know if anybody out there I
saw this episode during season two, but um, these military
contractors drop into west World to take care of the hosts,
(33:13):
the bad robots, and they are feeling on their vest
their location of the robots. So there's location over there there. Sorry,
there's a there's robbot over there. There's one over there
and then they can shoot them accordingly. But we've actually
used exactly that. For people who are blind, we've used
the same idea, which is they're wearing the vest and
they're feeling where people are around them, and oh, there's
somebody coming up behind me, there's someone over here on
(33:33):
my left, and so on, and then we can add
navigation directions on top of that. Um you know, so
it buzzes okay, go four, oh go, the left now
goes straight and so on. Um. So yeah, that was
a very cool, very cool opportunity that we had to
get our technology into this futuristic show. I love that
sequence in the show because I felt like like a
lesser show would have just copied Aliens and just had
(33:55):
you know, blips on a map. Uh And but this
felt this this fell thoroughly science fictional in nature, you know.
I mean, but then a GO course is using actual
technology that we're developing today. Exactly right now. You mentioned
West World bringing scientific topics or just topics concerning things
like consciousness out into the public square. The first season
(34:16):
at least discussed Julian James b cameral mind hypothesis or
brought that up a little bit and I know you
wrote about this a little bit in Incognito, but what
are your general thoughts on this hypothesis. You know, what's
interesting is that no one actually knows if it's correct
or not correct. So what Julian James proposed is that
it may be that you essentially have two sides to
(34:39):
the brain, the left and the right side, literally the
two hemispheres, and that those used to be more separate
and um, so it was as though people were hearing
a voice from somebody else. And what he argues is
that if you look at ancient literature, like ancient Greek
literature and so on, there's always this thing about hearing
a voice from God and so on. Um. And the
argument is that very recently the left and right hemisphere
(35:02):
started connecting in a deeper way. Um, and so there
was this super highway of fibers that goes back and
forth between them. And so what we have now is
a unified consciousness instead of two separate voices going on
in our heads. As I said, nobody really knows that
this is right or not, because there's no simple way
to test this directly. What I argued an incognito, though,
(35:25):
is essentially a a distant cousin of that, which is
that What is absolutely clear is that we are not
a single thing. So we think of ourselves as individuals,
meaning not divisible into different parts. But but in fact
who you are is a collection of different neural networks
that all have different drives. And this is why we
can argue with ourselves and custed ourselves in contract with ourselves,
(35:48):
and canjole ourselves who's talking with whom? Here? It's all us,
but it's different parts of us. So this is why
if I take some warm chocolate chip cookies out of
the oven and put them in front of you, part
of your brain says, don't need your get fat, and
part of brain says that looks like a high energy sort.
You know, I totally want to eat those cookies. And
part of your brain says, okay, how about I eat
the cookies, but I'll go to the gym tonight or whatever.
(36:10):
Like everything that we do in our lives, we have
arguments with ourselves about okay, what should I do here?
Part of me want to eat, this part of me
doesn't want to, And so what's going on? There are
all the different voices, the different political parties of this
neural parliament that we have running under the hood. And
this is the framework that I built in an incognito,
is that we've got this parliament and the way you
(36:31):
go just depends on the majority vote in any given moment,
and so you're not one thing, You're a collection of voters.
All right. I have one one last question for you. Um,
if if you could go back in time and serve
as a science advisor on any past science fiction film,
what would it be. What would you most like to
go back and tweak or correct or make a little
(36:53):
more neuroscientifically interesting. Oh gosh, I have to think about
that off the top of my head. Um. Something like
the Matrix is terrific, because that's an example actually of
of a piece of fiction that got everybody talking about
this issue of how do you know? Like you know,
(37:14):
Descartes said, how would I know if I'm a brain
in a vat um and and I just think that
I'm feeling and hearing and seeing these different things, And
that that got upgraded that question by philosophers um at
different stages in history. But but essentially that's the question
is how do I how do I know? If there's
a bunch of scientists that are zapping my brain with
(37:34):
electrodes that are making me feel that I'm talking with
you on zoom, and the weather is nice outside and
so on. But then the matrix, I think, singlehandedly upgraded
that question too. How do I know if I'm in
the matrix if I am a simulation? And and as
things have gone on, especially in the last I don't
know ten years in Silicon Valley, it feels like people
talk about that question more and more seriously all the
(37:56):
time because you look at our computational capacity and you think, well,
it's it's really not that hard to make super sophisticated
VR in So what's this gonna look like in one twenty?
I mean, you could make something that is absolutely convincing.
I mean, forget it. You can do that. It's just
like a convincing So the question is, how would you
know if you exist in a simulation or not? And
(38:17):
what they cart concluded, by the way, is that there
is no way for him to know um, And this
is what led to his very famous declaration japon suit
I think therefore I am um, because what he meant
by that is, look, I don't know if I'm in
a simulation, but all I can tell you is that
(38:38):
there's somebody thinking about this question. So I exist, whoever, whoever,
whatever situation I'm actually and it doesn't matter. There's some
I that exists, and that was actually a quite important
move in philosophy. But the point is, we have absolutely
no way of knowing if we are in a simulation
or not. And uh, we don't even have any good
(38:58):
hypotheses about how we would be able to find that out.
And by the way, it might not matter. I mean,
you know, if I told you with certainty that we
are or are not, it would it might not change
anything about what you're doing. Um so, But so I
would love to have been involved in in that movie
and and add in just a few neuroscience e uh
twists and sentences and questions there. Awesome, David, thanks again
(39:22):
for chatting with me today. Great, Thank you, Robert. This
is blessed all right, So there you have it again.
The book is Live Wired, The Inside Story of the
Ever Changing Brain by David Eagleman. It's out now and
if you want to check out Neosensory, you can just
go to neo sensory dot com. If you'd like to
(39:42):
listen to other episodes of Stuff to Blow Your Mind.
You can find us wherever you get your podcast and
wherever that happens to be. We just asked that you rate,
review and subscribe. Thanks as always to Seth Nicholas Johnson
for his recording skills and editing skills and bringing all
this together especially short to turn around Today. And if
you would like to eat ellis about this interview, about
this episode, or about forthcoming episodes or past episodes, you
(40:05):
can do so at contact at Stuff to Blow your
Mind dot com. Stuff to Blow your Mind is production
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