far surpasses any animal in the animal kingdom.

It's what makes us special, but we still

don't understand how it arises, and so that's

what me and my lab were trying to figure out.

The thing that makes our brains so special

is the number of connections and the number of neurons.

At about 80 to 100 billion neurons,

that's about three times more than our closest relatives,

the chimpanzees.

And so it's thought that during human brain development

neuron production really skyrockets.

But when and how this happens is completely unknown.

So to get the answers to these questions

we've turned to growing human brain tissues in the lab.

In the past 10 years there's been a revolution

in this field, allowing researchers

to generate 3D tissues that look just like actual organs.

And essentially, it involves taking stem cells, which

have this amazing capacity to develop

into any tissue of the body, including brain tissue,

if we give them the right conditions.

And those conditions include a three-dimensional gel,

which essentially mimics the surrounding

tissue of the developing brain.

And what's really amazing about this is that,

when these cells are kept in just the right conditions,

they will then follow their own natural developmental

programme, generating neurons with the same timing

and positioning as an actual human developing brain.

So because we have these 3D mini brain tissues in a dish,

we now have access to human developing brain

tissue in a way that was never before possible.

We can actually really get hands-on,

and start looking inside of them by taking cross-sections,

looking at different cell types, and comparing different time

points to see what changes over time.

We can also do live imaging and actually watch

as human neural stem cells do generate neurons,

and then watch those neurons position themselves.

And this is something that was never before possible.

And so at the moment, we can observe these processes

very well, but what we'd really like to do

is start to challenge the system and look

at what's controlling the skyrocketing neuron production

that we're so interested in, and get

at the root of the question of what

makes our brains so unique.