we built and landed robots on Mars to learn more about space.

We conjured up theories about how the universe works — and then proved them right.

We sequenced the human genome to paint a complete picture of our dna. but as for the minds that

made this all possible, we still don’t know much about how those actually work.

Scientists have been trying to navigate the mechanics of our large, complicated brains

for hundreds of years.

What would be really helpful is if we had a map.

And in order to get one of those, we’re going to need some brave scientists and very

advanced technology.

So how close are we to mapping the human brain?

If we could build a complete map of our brain and translate it, imagine what we could do:

We think maybe that will give us clues as to the causes of various forms of mental illness,

learning difficulties, diseases of aging.

And that might better allow us to figure out, are there treatments?

Or prevent the onset of some of those illnesses.

A map of the brain could even help us understand other scientific mysteries, like the origins

of consciousness.

Our brain is so powerful that if we better understood how it worked, we might be able

to create smarter robots and computers.

There is this technology in our brain for ... actually, in the brain of every mammal,

that allow us to behave autonomously.

It is very power-efficient.

A map of the human brain is seen as so valuable that multiple efforts across the world are

underway to get us there.

Aside from some big projects in the U.S. — we’ll get to those later — the European commission

is funding 100 universities to create a detailed computer model of the human brain.

China also announced a project to map the brain, and so has Japan.

There’s even several private projects focused on this goal.

So what do we mean when we say a map of the human brain?

Specifically, we’re talking about creating something called a “connectome” — a

complete catalog of all the structures in the brain and how they connect.

We typically think of there being both a structural and a functional connectome.

So the structural connectome is the white matter fibers that connect different parts

of the brain or the synapses that connect neurons.

And we call that structural because there's a physical synapse there that we can measure

and look at.

We're kind of making more of a roadmap of connections among brain regions.But there's

also what we call functional connections in the human brain, which have to do with kind

of coordination and function across brain regions.

That means identifying parts of the brain that work together but don’t necessarily

touch.

We don’t have any fully mapped functional connectomes yet and the only structural connectome

we’ve fully mapped is of “C elegans,” a transparent nematode about 1 millimeter

in length.

Even though they've been able to do that, it's still a complex organism.

And there's still a lot of work to be done to understand how the interactions give rise

to even the relatively simple behaviors that the C elegans can accomplish.

The connectome of the c. elegans brain identifies 302 neurons.

And if researching and building that connectome was complicated, now imagine how exponentially

more difficult it is to do the same with humans, who have somewhere in the region of 100 billion

neurons.

This is probably the first obstacle scientists have to overcome in mapping our brains — the

sheer size and daunting complexity.

So, they have to start small, and I mean really small — the samples they are studying are

the size of a grain of sand.

Inside that small grain of sand, there's about 100,000 neurons and form about one billion

connections.

So now, you see our brain is more than a million times bigger than this grain of sand, so you

can see how much units are compressed in such a small space.

And the brain is always changing, which makes it even more difficult to study.

When we're born, the brain grows over the course of development.

It builds new neurons, we're learning and interacting with the environment and that's

also shaping brain connections and how different parts of the brain work together.

but then it also starts to change as we get older and we move into later in life.

To tackle these challenges, the Obama administration started the Brain Initiative in 2014, bringing

several scientific institutions together to understand and treat the human mind.

As part of that coalition, the Allen Institute is analyzing mouse brain samples to count,

catalog, and connect the many different cell types — as a foundation for eventually doing

the same for the human brain.

Using electron microscopy, the team imaged billions of tiny synaptic connections in a

cubic millimeter of mouse neocortex.

Mapping the, the brain, at least at the resolution that we do it is difficult because many things

have to go right in the series.

Preparing the sample has to be perfect.

Scientists had to section the grain-sized brain sample into 25,000 pristine slices 40

nanometers wide.

For reference, a strand of hair is five times as thick as that.

Then those slices were distributed over six electron microscopes to be photographed.

It took us about five months to take all the pictures of that millimeter cube.I don't have

the final tally, but there's certainly hundreds of millions of those.

This type of data gathering took exhaustive, dedicated work around the clock.

When all the images were collected, researchers could then segment each single neuron and

create a 3D wiring diagram...step one towards that complete structural connectome, which

the team estimates will take five years to finish.

In terms of data storage was about two petabytes of data.

That’s about 2 million gigabytes from just a millimeter.

To eventually work with bigger human brain samples, something about this process will

have to change, as it will eventually be the largest data set ever collected about anything

in the world.

I think substantial, substantial advances on sample preparations, sample sectioning.

And above all, the storage of such will be immense.

Either technology will have to evolve in a way that such storage is available or our

sampling will have to evolve in ways that we can compress that, that information that

we want to extract from it.

We’ll also need forms of technology that aren’t as invasive as this, so we can study

live human brains, too.

And to develop a really robust map, we’re going to need to work with more than just

1 single brain.

We’ll need to study young brains, old brains, male brains, female brains.

We collected a pretty interesting and unique sample of 1200 individuals.

The human connectome project, led by the NIH, is using non-invasive tools to study human

brains now.

So the main tool we use to start out is an MRI machine.

If we're looking at the structural connectome, we typically use something called diffusion

imaging.

It's looking at the diffusion of water along these white matter connections in the brain.

And if you have a nice strong connection going in a certain direction between two parts of

the brain, we can measure that.

We do something pretty different though when we look at the functional connectome in the

human brains.

So we still use an MRI scanner, but we use a different kind of sequence.

It's looking actually at blood flow in the brain that we think happens after there has

been neural activity.

So if you're looking at brain activity in a brain region going up and down over time,

you can say, "Are there other brain regions that show that same pattern?"

And if the patterns are very similar over time, we call those functionally connected

brain regions.

So far, the human connectome project has made a lot of advances in this area of mapping

the brain.

In 2016, they released the most detailed map of the cerebral cortex to date, discovering

97 new brain regions in addition to confirming the existence of 83 others.

We understand much more now about how different brain regions kind of wire up together to

form networks.

We're starting to get a good sense of how those networks relate to which types of behaviors.

Where I think we still have work to do is understanding exactly how those contribute

or are changed by the experience of illnesses, how different kinds of environmental factors

might have an impact.

So this challenge is immense.

It will push our technology and creativity to their furthest limits; but so did sending

robots to mars, and sequencing the human genome... and we did all that.

So how close are we to mapping the human brain?

The biggest barriers keeping us from building a highly detailed human connectome is really

technology.

In my scientific lifetime, the progress has been exponential.

So I wouldn't be surprised in 10 or 20 years if we had a sort of dramatic leap in our understanding.

I think we may never have a map of every connection in the human brain in the sense of understanding

exactly how they interact together to give rise to exactly all the human behavioral and

cognitive and emotional abilities.

That's a tall order and I'm not entirely convinced that we will ever be there.

Looking at the shapes of those neurons they are beautiful.

They make me happy.

We and our collaborators are the first ones to see such, such, such detail at such scale

on the brain and that's like the, the old explorers when they arrived at the new continent.

We are, you know, we are mapping this, we are going into, into a territory where, where

things are new.

For more episodes of How Close Are We, check out this playlist right here.

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Thanks for watching.