you may perceive language as one big
function the brain performs
interestingly though it's divided into a
lot of sub functions this video will
discuss how your brain speaks and
understands language and what happens
when those functions are disrupted first
let's go over some basic neuroanatomy
for about 90% of right-handed people
language functions are centralized in
the left hemisphere of the brain lefties
and ambidextrous folks are somewhat more
likely to have language centralized in
the right hemisphere but still about 70%
of them will have language centralized
in the left hemisphere with in whichever
hemisphere is dominant the two main
areas associated with language are
Broca's area which helps us speak and
Wernicke's area which helps us
understand language Broca's area is in
the frontal lobe usually the left
frontal lobe and it's responsible for
language expression when Broca's area is
damaged people tend to have trouble
producing speech their words become
halting or slurred this is called
nonfluent aphasia or Broca's aphasia
I remember this by thinking that Broca's
aphasia means broken speech and aphasia
is just any type of disorder that
involves language when Verna Keys area
back in the temporal lobe is damaged you
get Verna keys aphasia which is quite a
different pattern of behavior than you
get with Broca's aphasia people have no
trouble producing words in fact words
kind of just tumble out of them but the
words that do come out don't make any
sense it's like listening to a bunch of
nonsense sentences people with Verna
Keys aphasia which is also sometimes
called fluent aphasia can also have
trouble understanding what other people
say and when both Broca's aphasia and
Verna gives aphasia are present then you
have something called global aphasia
because it globally affects language
instead of only affecting a subsection
of it Broca's area and Wernicke's area
are connected in the brain by a bundle
of nerve fibers called the arcuate
fasciculus one cool thing is that this
loop is
also found in deaf people who know sign
language so it's not specific to a
spoken language but the brain adapts to
use whatever modality is necessary for
communication when this connection is
damaged people experience something
called conduction aphasia their ability
to conduct information between listening
and speaking is disrupted which makes
them unable to repeat things even though
they understand what's being said pretty
crazy and once you think about how many
language specific functions you do every
day you might wonder how many different
types of aphasia there are and the
answer is a lot we have agraphia which
is the inability to write anomia which
is the inability to name things and
other specific difficulties in reading
spelling grammar pronunciation all sorts
of things you may not even realize that
you do effortlessly with a healthy brain
but Broca's aphasia and verdict is
aphasia are the most common language is
just one example of how our brain works
in general big tasks are subdivided into
small tasks which are then spread around
in different parts of the brain and this
can actually be a good thing because it
means if you have very localized a very
specific brain damage then you probably
won't completely lose your ability to
perform some highly important function
like communication in fact when
functions are divided like that it's
easier for your brain to adapt for
example when people have strokes that
affect the left hemisphere of their
brain they may have trouble speaking or
something right after the stroke but
over time and with proper therapy some
of those people are able to retrain
other speech related parts of their
brain by creating new connections
between neurons building these
connections in combination with some
recovery of the originally damaged part
of the brain can help these people speak
again with at least some degree of
fluency the brain's ability to adapt and
move functions to new parts is called
neural plasticity or synaptic plasticity
the neurons are plastic or flexible
enough to learn new routes and
connections thus allowing undamaged
parts of the brain to take over
functions
the damaged parts previously performed
even with perfectly functioning
hemispheres you might still have trouble
naming objects this can happen if
communication between the hemispheres is
disrupted by severing the corpus
callosum which is a thick band of nerve
fibers that connects your brains to
hemispheres
this creates what's called a split brain
patient because your brain is now split
into two parts people used to have to do
this sometimes as a treatment for
seizures but in addition to helping with
that problem
this surgery creates some pretty
interesting side effects in terms of
language so assuming that language is
centralized in the left hemisphere this
means that the right side of your brain
can't connect to the language side so
anything that you perceive on the right
side of your brain can't be named or
dealt with in terms of language now you
may have heard before that your brain
has what's called a contralateral
organization meaning that information
you perceive in your left visual field
gets processed by the right side of your
brain and vice versa so let's think
about what that means for a split brain
patient if you see an object on your
left and it gets sent to your right
hemisphere you won't be able to name it
you'd still be able to pick it up with
your left hand because again your right
hemisphere is controlling your left side
motor neurons but you'd have to kind of
turn your head so that the object would
be in your right visual field before the
language part of your brain would have
any access to it now when I say the
right visual field that doesn't mean
just your right eye it means the right
side of your body which you can view
with half of each eye so there you go
lots of pretty cool implications for how
our brain is organized and subdivided in
terms of language