professor Dave again let's learn about
language we just learned about brain
lateralization or the notion that
certain cognitive functions can be
localized more specifically in one
hemisphere of the brain over the other
language is one such function as it is
highly localized in the left hemisphere
attempts to understand why this is the
case can help us understand the
evolution of cerebral lateralization in
general so let's take a look at how the
brain processes language the motor
theory of lateralization proposes that
the left hemisphere controls fine
movements speech being one of these but
our ability to make a variety of noises
with our mouths is far from the full
story when it comes to language unlike
other animals we are able to take a
finite set of elements which comprise
some alphabet and use them to express
any idea imaginable new or old concrete
or abstract even monkeys and whales and
dolphins which do exhibit rudimentary
forms of speech can't do what we do they
do not have such fine motor control over
speech so as to produce the distinct
syllable so that we can but they are
also not as hardwired as we are to be
able to perceive and comprehend these
sounds something that is innate in
humans which are able to learn their
parents languages remarkably quickly in
infancy what are the specific areas of
the brain that are responsible for this
capacity to critical regions are called
Broca's area and Wernicke's area the
first of these is responsible for the
motor functions that allow us to
formulate syllables with our mouths
since damage to this area results in
impairment of this function without
affecting the ability to understand
language the second area is the one that
is responsible for the understanding of
language since damage to this region
doesn't
not impair the ability to vocalize but
results in complete nonsense being
spoken these two regions together with
the basal nuclei form a language
implementation system that analyzes
words that are heard and produces our
own speech in response a surrounding set
of cortical areas links this system with
other regions of the cortex that are
responsible for conceptualization of
ideas essentially enabling us to
communicate our thoughts this highlights
the features of language that are
lateralized though there are functions
of the opposing hemisphere that are also
relevant which allow us to interpret the
nonverbal components of language such as
body language gestures and any kind of
tone or quality that would signify the
emotional content of what is heard much
of what we have mentioned so far can be
considered part of the Verna key
Geschwind model this is comprised of
seven components two of which are
Broca's area and Wernicke's area which
we just discussed the others are the
primary visual cortex angular gyrus
primary auditory cortex arcuate
fasciculus and the primary motor cortex
all of these are in the left hemisphere
of the brain not surprisingly now let's
trace the brain activity that occurs
during a conversation according to this
model when you are listening to someone
talk their voice is converted into
signals that are sent to the primary
auditory cortex and then conducted to
Verna keys area this is where we can
imagine that the words are actually
comprehended as this is where the neural
representation of the thought underlying
the reply is generated which is then
sent via the arcuate fasciculus over to
Broca's area from there information is
sent to
the primary motor cortex which controls
the muscles in your mouth so that you
may respond instead when reading aloud
the visual information of the written
words is sent to the primary visual
cortex and this information is
transmitted to the angular gyrus which
translates the written word into the
corresponding auditory signal and sends
that to Verna keys area for
comprehension the rest follows the same
path already outlined we should note
that this is simply a model and is
likely somewhat an oversimplification of
brain function there is empirical
evidence to support this model relating
to patients with brain injuries in
specific areas and the observation of
the type and severity of function loss
but the model is not flawless it can't
account for all of the data and not all
of its predictions have been confirmed
but it is a reasonable model that serves
as a basic understanding of how the
brain perceives and produces language
there is plenty more to discuss here and
it is up for debate the degree to which
we are innately programmed to learn
language with syntactical and
grammatical rules fully formed in the
brain according to Noam Chomsky's theory
of universal grammar we will touch on
this again in a future linguistics
course but for now let's move on to some
other topics thanks for watching guys
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