True or false?

That's a fascinating phrasing because what the trolley dilemma actually represents is how poor humans are at making consistent decision-making on this stuff.

So should I explain the trolley dilemma for anyone who hasn't heard it? Yeah, please do.

Great.

You're standing by a railroad track.

You see a trolley is barreling down the track.

You understand its brakes are broken and it can't stop.

Can you dive into the neuroscience of that?

I'm really asking you a question here.

Yeah.

[clears throat] No, that's right.

We- we've traditionally been totally tied to what's going on with, with light and darkness, uh, in a way that we've, you know, drifted from now 'cause we have artificial light anywhere we want and that sort of thing.

But yes, what, what I'm talking about in the brain are these very, very ancient, uh, systems and in fact, this circuitry that causes...

These are called PGO waves, pontine, geniculate, occipital.

Doesn't matter the details, but these...

Can you break that down and explain? 'Cause our audience will be able to do this themselves.

And let's start at the core

... okay, so you've got 86 billion neurons, and they all communicate with these electrical signals that race around.

And so, uh, when a s- a single cell, a neuron, has an electrical spike, that spike races down the, the pathway called the axon, and to 10,000 little guys at the end, and it releases chemicals from some of them, which talk to the next guy and send electricity.

So the brain is an electrochemical system like that, and that's what's special about neurons is how they can communicate so fast, and that's how we can operate in the world so rapidly.

Okay, so the conceit in the show is that there's a little thing inserted that alters the electrical activity.

Now, it should be noted that it's never explained how it happens in the show.

So I, I ended up consulting for the third season about how would this work, so here's how I think this would work.

You get a little piece of information out, a little piece of information there, and that's kinda how the brain is, isn't it? That isn't about experience.

And was it ahead of its time, would you say, with hindsight? Like, it's just mind-blowing.

Thank you.

You know, I, I do think so.

We had a lot of interest in it, but of course, you know, deafness was our first go-to-market strategy.

As it turns out, the deaf market is, is very small, and it tends to be underemployed, and it tends to be very fractionated in terms of some people who are deaf really want to pick up on the environmental sounds of the world and know if somebody's knocking or honking or whatever.

But some people in the deaf community are very opposed to technologies that they see as, "Hey, somebody's trying to fix me, and I'm perfectly happy where I am." So it turns out that it, it's not really much of a market, so we were looking at all kinds of other things.

We ended up doing 72 different experiments in other kinds of senses that you could build for people.

[laughs]

So w- what is a dream? G- what is that?

Yeah, great question.

So it turns out a dream is activity in the visual cortex, and your mind is a natural storyteller.

So when the brain shoots random activity in there, you construct stories.

Now, the synapses, the connections that happen to be hot from the day, those are more likely to have activity running down those pathways, but it can go in any direction.

And the really interesting part is that we don't perceive it as just random splotches of light or something, but we always assign, uh, emotion to it.

Dreams, of course, are characterized by bizarreness and, uh, and magnified emotions, so, um, you know, you tend to be really worked up from it in one way or another.

So what, what do you, did, did you, how did that land with you? [laughs]

Mm-hmm

..."Oh, look, I'm comparing to this kid who grew up without food, and, and I'm gonna say there's this difference." Who the heck knows why the difference is there? Even a generation ago, there's so many differences in terms of diet and pollution and politics and blah, blah, but whatev-- like everything that you can't do it.

So I, I only mention this because I think it's very important.

A lot of people pipe off with things about, "Oh, the younger generation, their brain, this, that," but we don't actually know.

And I will tell you that I happen to be a cyber optimist on this point about what growing up with the internet does for young people.

I think it's gonna make them much smarter than the generation that came before, and here's why.

It has to do with the size of the intellectual diet that they can bring in.

-which is like thinking about it and trying to understand it.

it.

Yeah.

So, by the way, as a side note, I did the drop myself three times before I ran any subjects on it because I wanted to make sure it was safe.

And it's super terrifying every time.

Yeah.

The thing is, when you're falling backwards and I ask you afterwards, okay, Liz, how long did that take? And I give you a stopwatch.

And you imagine from the moment you were released to the moment you landed, you start the watch and you stop the watch.

ways gets taken by AI, if we outsource that to AI, will that be taken up by another part of our brain?

They're making more connections, and I'm trying to get more information about this because I want people to understand like how senses work and why somebody who's blind, for example, can hear really well and how those neurons actually can be, I guess, reutilized for something else because neurons need to stay relevant.

Yeah.

Okay, so that's exactly right.

So it turns out that um in the brain n- no territory lies fallow.

Everything is going to get used.

And so we think about this area at the back of the head, we think of that as the visual cortex, but yes, if you go blind, it's no longer the visual cortex.

It gets taken over by hearing, by touch, by memorization of words, by lots of things um because it's perfectly good ah territory.

Mm-hmm.

We love Eagleman.

I mean, uh, I have to say, I'm not a cerebellum expert, as such, so if somebody says, "Look, there's a new part of the cerebellum," I'd be interested, 'cause I, I didn't know about that.

And he'd found that the key to tapping into that flexibility was motivation.

Everything is about the motivation for it.

If I tried to run a rehab program for you, and I said, "Look, Rachel, we're gonna teach you how to play the tuba," and you said, "I really don't care about the tuba," and I'm like, "No, this is great.

You're gonna play the tuba," you're, you're just not gonna get very far because you need the right cocktail of neurotransmitters there for plasticity to happen, and that generally maps onto motivation.

in that case, that their density of memory is higher, and therefore, even though there's a perceptual difference, um, perhaps more accurate than, uh, for the person who was calmer? Or is there a threshold at which stress limits memory, and therefore, the person who is calmer has a more accurate memory?

Great question.

Well, it turns out, first of all, what victims often have is what's called weapon focus.

So if the other person has a knife or a gun, that's all they remember.

They- You know, "Describe the guy's face." "I don't remember the guy's face, 'cause I was staring at the gun." So it turns out that what they pay attention to is sort of the wrong thing for forensics purposes.

Um, that's number one, but number two is this much deeper issue that even amygdala memories are not necessarily accurate.

So, um, you know, our colleague, Elizabeth Phelps, um, did this experiment right after 9/11 in 2001.

Right.

So you just recorded a course for Peterson Academy.

I did.

Yep, it's on brain plasticity, which is really my favorite topic.

It's about how brains absorb the world around them and, uh, and adapt to them.

And y- you know, the interesting part about this is that we are the only species that is as plastic as we are.

So, you know, you see a zebra get born and in forty-five minutes it's running around or a dolphin is swimming after a few minutes of, of being born.

But if you see a Homo sapiens get born, they're not doing it as quickly and the reason is Mother Nature essentially came up with a different trick with us where she drops us into the world half-baked and we absorb the world around us, our language, our culture, uh, all, you know, we s- we take everything that's happened before us and we springboard off the top of that and this is the reason why Homo sapiens has taken over the planet and been so successful because we, u- unlike a, a horse that's essentially living the same life that horses have for, uh, you know, for generations, we are living different lives every time.

Mm