How to look inside the brain Carl Schoonover

a thousand-year-old drawing of the brain

it’s a diagram of the visual system and

some things look very familiar today

it’s two eyes at the bottom optic nerve

flowing out from the back it is a very

large nose that doesn’t seem to be

connected to anything in particular and

if we compare this to more recent

representations of the visual system

you’ll see that things have gotten

substantially more complicated over the

intervening thousand years and that’s

because today we can see what’s inside

of the brain rather than just looking at

its overall shape imagine you wanted to

understand how a computer works and all

you could see was a keyboard a mouse a

screen you really would be kind of out

of luck you you want to be able to open

it up crack it open look at the wiring

inside and up until a little more than a

century ago nobody was able to do that

with the brain nobody had had a glimpse

at the brains wiring and that’s because

if you take a brain out of the skull and

you cut a thin slice of it put it under

even a very powerful microscope there’s

nothing there it’s grey formless there’s

no structure it won’t tell you anything

and this all changed in the late 19th

century suddenly new chemical stains her

brain tissue were developed and they

gave us our first glimpses at brain

wiring the computer was cracked open

so what really launched modern

neuroscience was a stain called the

Golgi stain and they works in a very

particular way instead of staining all

of the cells inside of a tissue it

somehow only stains about 1% of them he

clears the forests reveals the trees

inside if everything had been labeled

nothing would have been visible so

somehow it shows what’s there spanish

neuroanatomists Santiago Ramon y Cajal

who’s widely considered the father of

modern neuroscience applied this Golgi

stain which yields data that looks like

this and and really gave us the modern

notion of the nerve cell the neuron and

if you’re thinking of the brain as a

computer this is the transistor and very

quickly cahal realized that neurons

don’t operate alone but rather make

connections with others that form

circuits just like in a computer today a

century later when researchers want to

visualize neurons

they light them up from the inside

rather than darkening them and there are

several ways of doing this but one of

the most popular ones involves green

fluorescent protein

now green fluorescent protein which

oddly enough comes from a bioluminescent

jellyfish is very useful because if you

can get the gene for green fluorescent

protein and deliver it to a cell that

cell will glow green or any of the many

variants now of green fluorescent

protein you get a cell to glow many

different colors and so coming up back

to the brain this is from a genetically

engineered mouse called Brainbow and

it’s so called of course because all of

these neurons are glowing different

colors now sometimes neuroscientists

need to identify individual molecular

components of neurons molecules rather

than the entire cell and there are

several ways of doing this but one of

the most popular ones involves using

antibodies and you’re familiar of course

with antibodies as the henchmen of the

immune system but it turns out that

they’re so useful to the immune system

because they can recognize specific

molecules like for example the coat

protein of a virus that’s invading the

body and researchers have used this fact

in order to recognize specific molecules

inside of the brain recognize specific

sub structures of the cell and identify

them individually and you know a lot of

the images I’ve been showing you here

are very beautiful but they’re also very

powerful they have great explanatory

power this for example is an antibody

staining against serotonin transporters

in a slice of mouse brain and you’ve

heard of serotonin of course in the

context of diseases like depression and

anxiety you’ve heard of SSRIs which are

drugs that are used to treat these

diseases and in order to understand how

serotonin works it’s critical to

understand where the serotonin machinery

is and antibody staining is like this

one can be used to understand that sort

of question I’d like to leave you with

the following thought green fluorescent

protein and antibodies are both totally

natural products at the get-go they were

evolved by nature in order to get a

jellyfish to glow green for whatever

reason or in order to detect the coat

protein of an invading virus for example

and only much later did scientists come

onto the scene and say hey these are

tools these are functions that we could

use in our

research tool palette and instead of

applying feeble human minds to designing

these tools from scratch there were

these ready-made solutions right out

there in nature developed and refined

steadily for millions of years by the

greatest engineer of all thank you