How to Change Your Brain & Improve Learning

00:00:00.000 | [silence]

00:00:02.500 | One of the biggest lies in the universe

00:00:05.020 | that seems quite prominent right now

00:00:07.200 | is that every experience you have changes your brain.

00:00:11.100 | People love to say this.

00:00:12.260 | They love to say,

00:00:13.140 | "Your brain is going to be different after this lecture.

00:00:15.460 | Your brain is going to be different after today's class

00:00:17.800 | than it was two days ago."

00:00:18.800 | And that's absolutely not true.

00:00:21.160 | The nervous system doesn't just change

00:00:23.400 | because you experienced something

00:00:24.580 | unless you're a very young child.

00:00:28.220 | The nervous system changes when certain neurochemicals

00:00:31.420 | are released and allow whatever neurons are active

00:00:35.560 | in the period in which those chemicals are swimming around

00:00:38.980 | to strengthen or weaken the connections of those neurons.

00:00:44.120 | Now, this is best illustrated

00:00:45.900 | through a little bit of scientific history.

00:00:48.680 | The whole basis of neuroplasticity

00:00:51.200 | is essentially ascribed to two individuals,

00:00:53.680 | although there were a lot more people

00:00:54.880 | that were involved in this work.

00:00:55.940 | Those two individuals go by the name David Hubel

00:00:59.040 | and Torsten Wiesel.

00:01:00.880 | David Hubel and Torsten Wiesel

00:01:02.140 | started off at Johns Hopkins,

00:01:03.760 | moved to Harvard Medical School.

00:01:05.760 | And in the '70s and '80s,

00:01:07.280 | they did a series of experiments

00:01:09.120 | recording electrical activity in the brain.

00:01:12.740 | They were in the visual cortex,

00:01:15.800 | meaning they put the electrodes in the visual cortex,

00:01:18.840 | and they were exploring how vision works

00:01:20.840 | and how the visual brain organizes all the features

00:01:23.500 | of the visual world

00:01:24.340 | as these incredible things we call visual perceptions.

00:01:27.460 | But Hubel was a physician,

00:01:31.640 | and he was very interested in what happens

00:01:35.000 | when, for instance, a child comes into the world

00:01:37.080 | and they have a cataract.

00:01:38.600 | The lens of their eye isn't clear, but it's opaque.

00:01:41.920 | Or when a kid has a lazy eye

00:01:44.360 | or the eyes have what's called strabismus,

00:01:46.200 | which is when the eyes either deviate outward or inward.

00:01:49.180 | These are very common things of childhood,

00:01:52.160 | especially in particular areas of the world.

00:01:54.580 | And what David and Torsten did is they figured out

00:01:58.160 | that there was a critical period

00:02:01.000 | in which if clear vision did not occur,

00:02:05.040 | the visual brain would completely rewire itself

00:02:09.480 | basically to represent

00:02:10.760 | whatever bit of visual information was coming in.

00:02:13.800 | So they did these experiments

00:02:15.500 | that kind of simulate a droopy eye or a deviating eye

00:02:19.320 | where they would close one eyelid.

00:02:20.640 | And then what they found is that the visual brain

00:02:22.640 | would respond entirely to the open eye.

00:02:24.720 | There was sort of a takeover of the visual brain

00:02:27.040 | representing the open eye.

00:02:29.120 | Many experiments in many different sensory systems

00:02:33.200 | followed up on this.

00:02:34.500 | There are beautiful experiments, for instance,

00:02:36.560 | from Greg Rechenzohn's lab up at UC Davis

00:02:39.480 | and Mike Merzenich's labs at UCSF

00:02:41.960 | showing that, for instance,

00:02:43.380 | if two fingers were taped together early in development,

00:02:46.800 | so they weren't moving independently,

00:02:48.520 | the representation of those two fingers

00:02:50.120 | would become fused in the brain

00:02:51.640 | so that the person couldn't actually distinguish

00:02:54.620 | the movements and the sensations

00:02:55.960 | of the two fingers separately, pretty remarkable.

00:02:59.160 | All of this is to say that David and Torsten's work,

00:03:03.500 | for which they won a Nobel prize,

00:03:05.400 | they shared it with Roger Sperry,

00:03:07.040 | their work showed that the brain is in fact

00:03:11.520 | a customized map of the outside world,

00:03:13.400 | we said that already,

00:03:14.740 | but that what it's doing is it's measuring

00:03:17.200 | the amount of activity for a given part of our body,

00:03:20.760 | one eye or the other, or our fingers,

00:03:23.000 | this finger or that finger,

00:03:24.180 | and all of those inputs are competing

00:03:26.740 | for space in the brain.

00:03:28.840 | Now, this is fundamentally important

00:03:30.760 | because what it means is that

00:03:32.600 | if we are to change our nervous system in adulthood,

00:03:36.000 | we need to think about not just what we're trying to get,

00:03:39.720 | but what we're trying to give up.

00:03:41.020 | We can't actually add new connections

00:03:43.240 | without removing something else.

00:03:45.560 | And that might seem like kind of a stinger,

00:03:47.060 | but it actually turns out to be a great advantage.

00:03:49.560 | One of the key experiments that David and Torsten did

00:03:53.920 | was an experiment where they closed both eyes,

00:03:56.680 | where they essentially removed all visual input

00:03:59.780 | early in development.

00:04:01.020 | Now, this is slightly different than blindness

00:04:02.600 | because it was transient,

00:04:03.720 | it was only for a short period of time,

00:04:05.520 | but what they found is when they did that,

00:04:07.440 | there was no change.

00:04:08.700 | However, if they closed just one eye,

00:04:11.200 | there was a huge change.

00:04:12.960 | So when people tell you,

00:04:14.400 | oh, at the end of today's lecture,

00:04:16.200 | at the end of something,

00:04:17.540 | your brain is going to be completely different,

00:04:19.660 | that's simply not true.

00:04:20.720 | If you're older than 25,

00:04:22.080 | your brain will not change

00:04:23.940 | unless there's a selective shift in your attention

00:04:27.520 | or a selective shift in your experience

00:04:30.280 | that tells the brain it's time to change.

00:04:34.040 | And those changes occur through the ways

00:04:36.320 | I talked about before,

00:04:37.140 | strengthening and weakening of particular connections.

00:04:39.380 | They have names like long-term potentiation,

00:04:41.120 | long-term depression,

00:04:42.000 | which has nothing to do with emotional depression,

00:04:43.680 | by the way, spike timing dependent plasticity.

00:04:45.920 | I threw out those names not to confuse you,

00:04:48.340 | but for those of you that would like

00:04:50.000 | more in-depth exploration of those,

00:04:52.280 | please, you can go Google those and look them up.

00:04:54.600 | There are great Wikipedia pages for them

00:04:56.120 | and you can go down the paper trail.

00:04:57.480 | I might even touch on them in some subsequent episodes.

00:05:00.160 | But the important thing to understand

00:05:02.240 | is that if we want something to change,

00:05:04.560 | we really need to bring an immense amount of attention

00:05:07.880 | to whatever it is that we want to change.

00:05:10.040 | This is very much linked to the statement I made earlier

00:05:12.520 | about it all starts with an awareness.

00:05:15.540 | Now, why is that attention important?

00:05:18.080 | Well, David and Tornsten won their Nobel prize

00:05:21.280 | and they certainly deserve it.

00:05:22.160 | They probably deserve two

00:05:23.040 | because they also figured out how vision works.

00:05:24.640 | And I might be biased

00:05:25.840 | 'cause they're my scientific great-grandparents,

00:05:27.340 | but I think everybody in the field of neuroscience agrees

00:05:30.320 | that Hubel and Wiesel, as they're called,

00:05:34.200 | H and W for those in the game,

00:05:36.600 | absolutely deserved a Nobel prize for their work

00:05:39.100 | because they really unveiled the mechanisms

00:05:41.640 | of brain change, of plasticity.

00:05:43.840 | Hubel and Wiesel did an amazing thing for science

00:05:46.900 | that will forever change the way

00:05:48.500 | that we think about the brain.

00:05:50.180 | However, they were quite wrong

00:05:52.560 | about this critical period thing.

00:05:54.620 | The critical period was this idea

00:05:56.820 | that if you were to deprive the nervous system of an input,

00:06:00.300 | say, closing one eye early in development,

00:06:03.220 | and the rest of the visual cortex is taken over

00:06:05.620 | by the representation of the open eye,

00:06:07.640 | that you could never change that unless you intervened early.

00:06:11.820 | And this actually formed the basis for why a kid

00:06:14.440 | that has a lazy eye or a cataract,

00:06:17.040 | why even though there's some issues

00:06:18.740 | with anesthesia in young children,

00:06:20.960 | why now we know that you want to get in there early

00:06:23.600 | and fix the cataract or fix the strabismus.

00:06:27.280 | That's what ophthalmologists do.

00:06:29.520 | However, their idea that you had to do it early

00:06:32.860 | or else there was no opportunity

00:06:34.600 | to rescue the nervous system deficit later on,

00:06:38.480 | turned out wasn't entirely true.

00:06:41.820 | In the early '90s, a graduate student

00:06:44.580 | by the name of Greg Reckensohn was in the laboratory

00:06:46.980 | of a guy named Mike Merzenich at UCSF.

00:06:49.820 | And they set out to test this idea

00:06:52.440 | that if one wants to change their brain,

00:06:55.020 | they need to do it early in life

00:06:56.580 | because the adult brain simply isn't plastic.

00:06:58.980 | It's not available for these changes.

00:07:01.620 | And they did a series of absolutely beautiful experiments.

00:07:05.140 | By now, I think we can say proving

00:07:08.660 | that the adult brain can change

00:07:11.160 | provided certain conditions are met.

00:07:13.720 | Now, the experiments they did are tough.

00:07:17.080 | They were tough on the experimenter

00:07:18.360 | and they were tough on the subject.

00:07:19.820 | I'll just describe one.

00:07:21.100 | Let's say you were a subject in one of their experiments.

00:07:23.820 | You would come into the lab and you'd sit down at a table

00:07:26.960 | and they would record from or image your brain

00:07:31.340 | and look at the representation of your fingers,

00:07:33.480 | the digits as we call them.

00:07:35.600 | And there would be a spinning drum,

00:07:37.280 | literally like a stone drum in front of you

00:07:41.240 | or metal drum that had little bumps.

00:07:43.360 | Some of the bumps were spaced close together,

00:07:45.360 | some of them were spaced far apart.

00:07:47.320 | And they would do these experiments

00:07:48.980 | where they would expect their subjects

00:07:51.160 | to press a lever whenever, for instance,

00:07:54.440 | the bumps got closer together or further apart.

00:07:56.960 | And these were very subtle differences.

00:07:58.760 | So in order to do this,

00:07:59.600 | you really have to pay attention

00:08:01.640 | to the distance between the bumps.

00:08:03.560 | And these were not braille readers

00:08:05.160 | or anyone skilled in doing these kinds of experiments.

00:08:08.020 | What they found was that as people paid

00:08:11.080 | more and more attention to the distance between these bumps

00:08:14.720 | and they would signal when there was a change

00:08:16.200 | by pressing a lever.

00:08:18.120 | As they did that, there was very rapid changes,

00:08:20.800 | plasticity in the representation of the fingers.

00:08:24.080 | And it could go in either direction.

00:08:25.680 | You could get people very good

00:08:27.240 | at detecting the distance between bumps

00:08:29.740 | that the distance was getting smaller

00:08:31.240 | or the distance was getting greater.

00:08:33.600 | So people could get very good at these tasks

00:08:35.440 | that you're kind of hard to imagine

00:08:37.000 | how they would translate to the real world

00:08:38.480 | for a non-braille reader.

00:08:39.740 | But what it told us is that these maps of touch

00:08:43.100 | were very much available for plasticity.

00:08:45.540 | And these were fully adult subjects.

00:08:48.000 | They're not taking any specific drugs.

00:08:50.000 | They don't have any impairments that we're aware of.

00:08:52.560 | And what it showed,

00:08:53.960 | what it proved is that the adult brain is very plastic.

00:08:56.720 | And they did some beautiful control experiments

00:08:58.880 | that are important for everyone to understand,

00:09:00.920 | which is that sometimes they would bring people in

00:09:02.560 | and they would have them touch these bumps

00:09:05.360 | on this spinning drum,

00:09:07.000 | but they would have the person pay attention

00:09:08.640 | to an auditory cue.

00:09:09.880 | Every time a tone would go off

00:09:11.320 | or there was a shift in the pitch of that tone,

00:09:13.840 | they would have to signal that.

00:09:15.120 | So the subject thought they were doing something related

00:09:16.900 | to touch and hearing.

00:09:17.740 | And all that showed was that it wasn't just the mere action

00:09:21.560 | of touching these bumps.

00:09:23.280 | They had to pay attention to the bumps themselves.

00:09:25.560 | If they were placing their attention

00:09:27.700 | on the auditory cue on the tone,

00:09:30.780 | well, then there was plasticity

00:09:32.300 | in the auditory portion of the brain,

00:09:34.200 | but not on the touch portion of the brain.

00:09:36.080 | And this really spits in the face of this thing

00:09:39.760 | that you hear so often,

00:09:41.420 | which is every experience that you have

00:09:43.040 | is going to change the way your brain works.

00:09:44.840 | Absolutely not.

00:09:46.080 | The experiences that you pay super careful attention to

00:09:51.560 | are what open up plasticity.

00:09:53.600 | And it opens up plasticity to that specific experience.

00:09:58.300 | (upbeat music)

00:10:01.700 | (upbeat music)

00:10:04.280 | (upbeat music)

How to Change Your Brain & Improve Learning | Dr. Andrew Huberman

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