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