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MCAT
Course: MCAT > Unit 10
Lesson 11: Language- Language questions
- Language questions 2
- Theories of the early stages of language acquisition
- Language and the brain: Aphasia and split-brain patients
- Theories of language and cognition
- Theories of language development: Nativist, learning, interactionist
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Language and the brain: Aphasia and split-brain patients
Learn about language areas of the brain and the effects of damage to those parts of the brain. By Carole Yue. . Created by Carole Yue.
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- At, Carole gives some clarification on the meaning of "right visual field" as the right side of the body. Does she mean the right side of what is perceived by the left eye in addition to all of the right eye or something else? 5:53(7 votes)
- About a half of the nerve of each eye goes from eye to visual cortex in the same hemisphere, and the other half goes to the visual cortex in the other hemisphere. You effectively get half the signal of each eye in each half of your brain. According to http://www.medicalook.com/human_anatomy/organs/Optic_nerve.html it really is the actual left or right half of what you see, which explains the need to move your head, as she stated at. 5:45(13 votes)
- What about stammering or stuttering? Is that a form of brain impairment?(5 votes)
- A recent study found that stuttering is actually an undescribed type of non-fluent aphasia: Perfusion Aphasia. Source: http://onlinelibrary.wiley.com/doi/10.1002/hbm.23487/abstract;jsessionid=D3D030134DBDFF1A949861C0880337FF.f04t01(6 votes)
- If you have Broca's aphasia, will you still be able to understand what your friend is saying? Or will you just have broken speech?(2 votes)
- People with Broca's aphasia are capable of understanding everything that is said to them, but just have difficulty finding the words to express themselves.(3 votes)
- Why is the colour of the human brain white inside and grey outside. And why is it the reverse for the spinal cord(2 votes)
- Neural tissue itself grey, unless it is surrounded by myelin (produced by oligodendrocytes in the central nervous system, which includes the brain and spinal cord). Myelin allows impulses to travel in nerves (specifically, the axon of nerves) more quickly. So in the brain, the unmyelinated cell bodies of the neurons are on the exterior, and the myelinated axons are on the interior. In the spinal cord, the locations are reversed.(2 votes)
- How big is the broca in a human brain ?(1 vote)
- Broca's area is not that big - here is a picture:
https://en.wikipedia.org/wiki/Broca%27s_area#/media/File:Broca%27s_area_animation.gif(3 votes)
- What is Broca's area & Wernicke's area?(1 vote)
- Broca's area is responsible for creating speech, Wernicke's area is responsible for interpreting it. People with Broca's aphasia (damage to Broca's area) have trouble speaking but can usually comprehend fine, people with Wernicke's aphasia (caused by damage to Wernicke's area) can usually speak fine but have difficulty or are unable to comprehend written&spoken language.(2 votes)
- At, Carole says that stroke could affect the left side of your brain and you can recover from it from various therapies. I was wondering `how stroke affects your brain, does damage it by slowing your brain growth or does it make you forget things? If you can't speak for a while it must be something that is long term, right? 3:50(1 vote)
- Well, the way I understand it is your brain can adapt to changes, which is called plasticity. Say our left hemisphere is damaged, neurons might find "new" ways with their axons. The right side of the brain might be able to take over certain functions aswell (?).
The brain doesn't grown in an adult brain, however, the connections between neurons change, might be because of damage or new memories being formed. Why we forget things is hard to answer because we don't really know what memory is, just that some memories form in a brain structure called the hippocampus (consolidation).(2 votes)
- what's an example of neural plasticity?(1 vote)
- Say you loose a finger, then your upper motor neurons in the primary motor cortex that previously controlled that finger will get "assigned" to another finger. The same actually happens during anaesthetics, but this process is reversible:)!(2 votes)
- how dose the Broca area and Wrenick area get damaged??(1 vote)
- There are many ways areas of the brain can be damaged. Here are a few to consider: stroke (preventing blood from serving that area), trauma, brain tumor, chronic alcohol abuse (esp. Wernicke), etc.(2 votes)
- how did you know what part of the brain controls what?(1 vote)
- Well, it is more or less trial and error. Neuroscientists observe different behavioral patterns in people with certain parts of the brain missing. So then they simulate the brain of the person (with a specific part of the brain absent) in an animal, say a mouse, and note their observations. When they observe similar abnormal behaviors in many animals and humans alike, researchers can find the part of the brain that controls a certain function.(1 vote)
Video transcript
You may perceive language
as one big function the brain performs. Interestingly,
though, it's divided into a lot of sub-functions. In this video, we'll 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. Within 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 non-fluent
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 Wernicke's area, back in
the temporal lobe, is damaged, you get Wernicke's
aphasia, which is quite a different
pattern of behavior than you get with
Broca's apahasia. 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 Wernicke's aphasia,
which is also sometimes called "fluent aphasia," can also
have trouble understanding what other people say. And when both Broca's aphasia
and Wernicke's 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 apahasia
and Wernicke's 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 or 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. And 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 that 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 band of nerve fibers
that connects your brain's two 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
in 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
that 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.