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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My stroke wiped out my ability to read! My ability to recognize letters and read them correctly was scrambled. Is there an aphasia type for that? Technology help me compensate and I'd be worse off if this stroke had happened before the appearance of tech tools to help me compensate.
Audrie, Thanks so much for your reply and for putting a name to my veriest of Aphasia. Considering how I could have been damage by my stroke, I count myself lucky indeed to get away with Alexia. Thanks for reaching out!
David, there is a term for impaired reading after a stroke - Alexia. It’s encompassed in Aphasia because it typically occurs after a stroke and impacts language processing. In the case of Alexia, the brain finds it more difficult to process words when they are presented in writing, as opposed to being verbally spoken. There is also Agraphia, a language disorder in which people may find it difficult to write.
I’m glad you are able to use technology to compensate for alexia. It’s also something that can be targeted in speech therapy, if that’s something you are doing!
Can you please explain the "Model of single-word processing for auditory and written word perception and production. Including processes involved in picture naming."
And levels of breakdown and impact?
I was given this subject as my presentation topic for my college biology class... Little did I know how fascinating this is and learned many things I wasn't aware of. Thank you for perfectly explaining it in this video!
Language and the brain: Aphasia and split-brain patients
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 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 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.
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 fied 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 your 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.
This is a great explanation, especially for those who suffer from aphasia. A family member had a stroke several years ago and suffers from aphasia, she has been fighting ever since to understand what happened to her and to be able to explain to others. Having aphasia makes this very difficult. Videos like this are very helpful, so thank you!
I don`t get it, if you`re a split brain patient, how come your hemispheres can control the contralateral parts of your body?
Motor commands get sent from the (for example) right hemisphere to the left side of your brain through the corpus callosum, right?
No it doesn't, your motor commands don't go through your corpus callosum, It is just like that your left hemisphere controls the right side of your body contralaterally because motor fibers (which carry the motor commands from your brain) cross to the opposite side in their way down to the spinal cord and to be specific this crossing occurs (in the medulla of the brain-stem) has nothing to do with the corpus callosum which is just a group of fibers that allows your two hemispheres to communicate with each other, I know your comment is 2 yrs ago but I hope I helped even though it's late.
Antidepressants are medications that can help relieve symptoms of depression, social anxiety disorder, anxiety disorders, seasonal affective disorder, and dysthymia, or mild chronic depression, as well as other conditions.
They aim to correct chemical imbalances of neurotransmitters in the brain that are believed to be responsible for changes in mood and behavior.
Depression Medications (Antidepressants)
These are the most commonly prescribed type of antidepressant.
Serotonin and noradrenaline reuptake inhibitors (SNRIs) are used to treat major depression, mood disorders, and possibly but less commonly attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), anxiety disorders, menopausal symptoms, fibromyalgia, and chronic neuropathic pain.
SNRIs raise levels of serotonin and norepinephrine, two neurotransmitters in the brain that play a key role in stabilizing mood.
Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed antidepressants. They are effective in treating depression, and they have fewer side effects than the other antidepressants.
SSRIs block the reuptake, or absorption, of serotonin in the brain. This makes it easier for the brain cells to receive and send messages, resulting in better and more stable moods.
They are called "selective" because they mainly seem to affect serotonin, and not the other neurotransmitters.