Neuroscientist Explains One Concept in 5 Levels of Difficulty

My name's Bobby Kasthuri, I'm assistant professor at

the University of Chicago, I'm a neuroscientist at

Argonne National Labs.

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What the connectome is, is it's a kind of a newly made-up

term for describing a kind of neuroscience research where we

try to map the brain at a scale that's

never been mapped before.

Every person here can leave with understanding it

at some level.

(joyful music)

Do you know why we're here today?

Because we're talking about science.

Yes, we're gonna talk about science and we're gonna talk

about a very specific kinda science,

about people who study brains.

Do you know what a brain is?

What is it?

Um, something that helps you remember things.

Definitely.

So what we're gonna talk about,

this is something that people study

in the brain called the connectome.

Oh.

Do you know that your body is made up of really tiny

things called cells?

Um, yes, I know that.

Okay, well there's more cells in your brain,

like way more cells, than all the stars we can see.

(Daniel gasps)

(Bobby laughs)

And so what the connectome is, is we'd like to know

where every cell in your brain is and how it talks

to every other cell in your brain.

Oh.

That was awesome, Daniel, thank you.

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Connectone?

Connectome.

To be honest, I have no idea.

That's good, that's a great place to start.

There are cells in your brain.

Those brain cells are connected by wires to each other.

Electricity travels down those wires and communicates

from one part of the brain to the other part of the brain,

and each of those brain cells makes, you know,

a thousand connections, it's something like

a hundred trillion connections.

Whoa.

In one brain, in your brain.

Could I take all of that information

and put it inside a computer?

Would that computer then be you?

Computers they don't have feelings,

they won't have feelings and I think that's one thing that

makes the human race strong.

I would say that that map also has your feelings in it

because, here's why, your feelings,

most neuroscientists think, come from your brain anyway,

and amazingly, whether when you feel happy or sad or angry

or scared, that's just brain cells

communicating with each other.

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So, I think today we're gonna talk about a connectome.

Have you ever heard of that?

A connectome?

Yeah.

No, I don't think so. Awesome, good.

(laughs)

It's a map of all the connections

between every neuron in your brain.

It literally, in a human brain, something like a map of

the one quadrillion connections that a

hundred billion neurons make with each other.

Is this like a map where, that's like an actual visual

representation, like using microscopy?

Yes. Or just data?

Wow, wow. Yeah.

I'm understanding more so that it's these,

a mapping of the circuitry,

the pathways between neurons that can lead

to evidence of patterns in your brain that are common

between different people.

We have to use electron microscopes

and then what we have been developing a way

to slice the brain into really thin slices,

use an electron microscope to take a picture of each slice,

and then use computers to put it all back.

Imagine that we could get a map of every connection, right?

And we knew how neurons fire.

Do you think we could put that in a computer, that map,

and then therefore, that computer should be able to think

just like the brain that we extracted it from?

Well, the computer only communicates with itself in binary

so it only has two options, it can only ask itself yes or no

questions, but a human brain has

an infinity of directions that it can go.

Neurons are also digital.

Meaning a Neuron either fires or it doesn't fire,

so that's either one or zero.

And it's the combination of those ones or zeros that

actually produce the 10 thousand different

answers that you say.

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It's a large scale attempt to understand the wiring map

of the brain, essentially.

Yeah, great.

I think that it's definitely needed.

Huh.

Understanding the anatomy of the brain is definitely

important but, it doesn't necessarily tell us everything

about the function, there's some sort of temporal order

from neuron to neuron and region to region

that we may not be able to pick up.

This is where it gets really crazy.

Could we simulate that map inside a computer

and would that computer then be thinking

like that original brain from which we made the map?

I mean that's not the person, I mean, having a

representation of someone's neural network

is just that,

it's just a representation of the neural network.

Huh. I mean.

Because there's more to you in here

than just information passing between neurons.

I'd like to think so.

Huh.

It would be like if you simulated a hurricane.

Imagine we could keep track of every variable

of a hurricane. Ever.

Wind speed, every water molecule, et cetera, et cetera.

Temperature.

And we put that inside a super-fast computer

and we simulated it, right?

I don't think anyone would think that

the inside of the computer would get wet.

Even though we had simulated the hurricane perfectly,

that wetness is consciousness, it's what we are.

Is it ethical to imagine mapping a male brain versus

a female brain to look for differences between those,

to explain alleged behavioral differences between them?

Every single person is different and so it should be

okay to map every single person's brain.

I mean I understand that there are,

that it's very sensitive, you know?

Wait, what do you think is sensitive?

Mapping an Indian brain versus a Caucasian brain, or,

politically I think that people may have some issue with

mapping out what causes

or what makes a difference between

different types of people.

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Maybe a wiring diagram is not sufficient to understand

the brain, and it would be crazy to think that that would be

sufficient, actually.

If you limit the connectome to be just the wiring diagram

without, you know, more information about myelination

or glial cells, all types of environmental features that

surround the neurons and axons then you have an incomplete

picture, no doubt.

Sometimes when people get, they worry about connectomics,

I think what they're actually worrying about is that

it's the end of the that we used to do neuroscience.

What do you think about memory?

Do you think that there's ways of resolving what the

substrate of human memory is,

you know, is it just LTP and LTD?

I'm not sure if you had a connectome of a human brain,

of an adult human, I would be able to read out

memories from that.

You don't think it's just the synaptic weights,

like an artificial neural network that's trained

to do particular things?

It could absolutely be but without knowing

what the weights were before the memory was made.

What if you had a violinist learn a piece of Bach music,

could you find those notes somewhere in their brain

if they didn't know before?

Yes.

I'm a musician and I don't think it's possible.

I think that there are too many, you know,

so much of it is associative to what you already know.

So and a musician, how much of it do you think

is in your hands versus in your brains?

Meaning like, you do have connections in your muscles

from the nerves that are from your spinal cord,

what if some of the learning is there?

Are you still doing EM or?

Yeah.

We do a lot of X-ray in addition to EM

and this is actually, I'm not saying it's the only problem,

but it's the only problem that needs to be solved

right away, is that the data analysis, right?

In fact, I think we calculated that there aren't enough

humans ever to map a mouse brain

where you collect every connection and et cetera

so the problem is to get algorithms to trace,

to recognize things in brains

the way humans would recognize things in brains,

or map things, trace things in brains.

It's gonna cost a lot of money to imagine setting

the gold standard for the wiring diagram even once

and those are the kinds of ethical concerns

that I'm worried about.

One of the things that we're not doing well as a field

is sort of educating and telling people beyond our field

the benefits of what we could achieve

but I'm impressed that when you talk to people about

something that seems kind of crazy and outlandish

and perhaps they hadn't been talking about before,

it doesn't take 'em long to come to a kind of

considered opinion, especially children.

I think it's kind of amazing.

I mean, I do hope that more people talk about brains

and what we use brains for

and the ways that we shouldn't use our brains.

So I think this field has the opportunity

to make that more real.