language is a pretty key part of what it
means to be human
okay we're really social so we use
language to communicate and connect with
our fellow human beings but language is
complex and that complex communication
requires some pretty complex neural
architecture to handle the job I'm alie
astrocyte and this week on neuro
transmissions let's talk about Lex akan
language is generally considered to be
universal and unique to all humans
amazingly babies learn their primary
language only by being exposed to it it
doesn't require any special teaching and
deaf kids who grow up without formal
sign language will often invent their
own home signs to communicate with
family and friends of course language is
an extremely complex behavioral system
so it's not very easy to figure out
exactly where it's coming from
early neuroscientists didn't have tools
like fMRI or EEG to look inside the
brain the way that we do today this made
it pretty challenging to study the
neuroscience of language it's really
difficult to get a close look at what's
going on in the brain during language
production the earliest research on
brain regions involved in language came
from case studies of patients who had
suffered from brain lesions injuries
resulting in tissue death in the brain
this kind of research helped doctors
discover two key brain regions Broca's
area and Wernicke's area Broca's area
was discovered by a man named Paul Broca
a French physician also called
expressive aphasia patients with an
injury to Broca's area know exactly what
they want to say they just can't find
the words or grammar to properly express
it now tell me what this thing was with
your legs last week or a week before oh
no good
ah
Wernicke's area was discovered by the
German neurologist Carl Wernicke who
first noticed the link between damage to
the back of the superior temporal gyrus
and a particular type of difficulty in
speech this aphasia makes it difficult
for a patient to properly understand
language but they have no problems
producing language using grammatical
sentences that don't make any sense this
is why word akise aphasia is sometimes
called fluent aphasia we save a lot of
hands on hope for people's for us other
hands of what you get but I talk with a
lot of hand for him sometime
am i talk of anymore to saying using
more modern techniques researchers have
begun to learn new things about other
brain regions that seem to play
important roles in language a particular
kind of test called the wada test has
helped demonstrate how language is
localized to one side of the brain or
the other don't try this test at home
patients are injected with a barbiturate
through the carotid artery which puts
that half of the brain to sleep doctors
can then perform different cognitive
tests on the patient to determine what
kinds of things they can and can't do
when half of their brain isn't
functioning this kind of testing has
found that most people process language
in their dominant hemisphere which for
most people is usually the left
hemisphere which controls the right side
of the body when that hemisphere is put
to sleep patients have a hard time
speaking and understanding language in
an earlier video we talked about how we
here using the auditory cortex which it
should come as no surprise is one of the
earliest places where speech is
processed this is where our brain
consciously registers the sound of words
and begins to process them humans mostly
use speech to communicate with each
other so language is mostly an auditory
ability it turns out that a lot of the
brain regions that we use to hear sounds
are also used to interpret speech some
more recent neuroimaging studies have
led researchers to propose that language
information gets split into what they
call a dual stream model similar to the
to processing streams we talked about in
the visual system when it comes to
language this model says that
information is sent along the dorsal
pathway to brain regions on both sides
of the brain this pathway is sort of the
speech part of the system it translates
the information it gets from speech
input and allows us to reproduce those
same speech
patterns kind of like how the dorsal
stream in the visual system is the wear
pathway that helps us navigate space
these dorsal streams help us determine
our movements including our mouth
movements the ventral stream passes
information along the dominant
hemisphere this stream is more the what
pathway with language this means the
ventral stream allows us to identify the
content of speech and understand what
those words mean so the ventral stream
is what lets you hear the word ball
identify it and visualize a ball in your
own mind providing you with context for
the words that you're hearing lots of
researchers are using many different
tools to continue breaking down the ways
our brain hears processes and interprets
language some scientists are even using
animal models to answer questions about
different aspects of language different
bird species use unique bird songs to
communicate and are studied as a model
for complex vocabulary and grammatical
processing some primates like the tiny
marmoset are used to study the neural
basis of social communication these
models won't answer all the questions we
have about language in the brain but
they can help us better understand it so
with time we'll know more about this
complex and unique behavior thanks for
joining us for this episode of neuro
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you