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  • - In early 2022,

  • action star and Hollywood legend Bruce Willis

  • stepped away from acting.

  • This piece of news was particularly poignant

  • because of the reason for his retirement: aphasia.

  • A language disorder

  • that affects a person's ability to communicate,

  • often caused by strokes, brain injuries, tumors,

  • or in Willis's case, dementia.

  • Even though the word language comes

  • from the Latin for tongue,

  • language is really more related to the brain

  • than any other part of the body.

  • It's where language happens.

  • Whether you're shaping words with your mouth,

  • signing them with your hands,

  • or writing them on paper,

  • the bulk of the work is going on up here.

  • While there is no one part of the brain

  • that handles everything speech-related,

  • there are some areas that are more involved than others.

  • Scientists have known this long before

  • the development of MRIs

  • and other brain scanning technologies. How?

  • Through the study and observation

  • of patients who have experienced language impairments

  • due to brain damage.

  • By determining what has been lost or impaired,

  • neuroscientists have been better able to understand

  • how our brains process language

  • and what language really is.

  • And now my brain-language connection

  • will communicate that to you.

  • I'm Dr. Erica Brozovsky,

  • and this is "Otherwords."

  • (upbeat music)

  • To learn more about the relationship

  • between language and the brain,

  • I spoke with Dr. Alexander Tan,

  • a pediatric neuropsychologist

  • with expertise in the assessment

  • of neurological and neurodevelopmental disorders

  • in children and adolescents.

  • So you're a neuropsychologist.

  • What is neuropsychology?

  • - The definition of neuropsychology literally is

  • the study of brain and behavior and that relationship.

  • So as a pediatric neuropsychologist,

  • we do checkups on different brain functions,

  • like attention, memory, visual perception, language.

  • And then using those results,

  • we can assess for brain disorders

  • and make sure that we are getting children the treatments

  • and supports that they might need

  • and track their development or their recovery over time.

  • - When it comes to the connection

  • between language and the brain,

  • the first answers were discovered in sort of a curious way.

  • Prior to technological advances in neuroimaging,

  • like functional MRIs,

  • doctors couldn't see what was happening in the brain

  • and observe what areas lit up with various stimuli.

  • The only way to look at the brain was by opening it up.

  • In the 19th century,

  • physicians Paul Broca and Carl Wernicke

  • separately discovered two regions of the brain

  • through conducting autopsies on aphasic patients.

  • - [Dr. Tan] Dr. Broca and Dr. Wernicke were able

  • to locate specific parts of the brain

  • that have resulting impacts on their ability to

  • either express language or to comprehend language.

  • And those parts, now referred to as Broca's area

  • and Wernicke's area, are in the left frontal

  • or left temporal lobe, respectively.

  • And that was one of the first signals to us

  • that the left hemisphere is dominant for language.

  • - For more than 95% of right-handed people

  • and 60% of left-handed people,

  • the left hemisphere is dominant for language.

  • But that's not to say

  • that the language party is exclusively on the left side.

  • - Now that we've had more advancements in technology,

  • different kinds of imaging techniques,

  • we now are seeing that language actually involves a lot

  • of different parts of the brain,

  • including, you know, implicating all four lobes,

  • the gray matter and the white matter,

  • cortical and subcortical structures.

  • It's very much a complex ability

  • that involves communication and coordination

  • between a lot of different parts of the brain.

  • - When you see an image, say, this one,

  • you think, "Okay, yeah, sure, it's a ball,

  • or a car, or a unicorn."

  • But that's just the result.

  • Let's backtrack to what happened on the inside.

  • First, you process the visual input

  • so that you could recognize the object.

  • Then you have to convert the input into a semantic concept.

  • From there, you search through your mental Rolodex

  • of abstract representations

  • and pick the concept matching word.

  • Finally, you articulate the phonemes

  • that make up that word.

  • And if just one step doesn't work properly,

  • you might not be able to recognize the object,

  • or know what it's for,

  • or find the word you need,

  • or communicate the word to anyone else.

  • What is aphasia, first of all, and what causes it?

  • - So aphasia is essentially

  • an impairment in language abilities.

  • And it is typically caused by strokes,

  • brain injuries that affect certain parts of the brain,

  • or some kind of neurodegenerative condition,

  • like dementias or Alzheimer's disease.

  • - [Dr. Brozovsky] The two most common types of aphasias

  • are the ones named after Broca and Wernicke.

  • Damage to Broca's area may cause Broca's aphasia,

  • or expressive aphasia,

  • which means you can generally understand others

  • but have difficulty getting your words out.

  • It might be limited to single words or short phrases.

  • On the other hand, someone suffering

  • from Wernicke's aphasia,

  • or receptive aphasia,

  • will have trouble understanding language, even their own,

  • but is still capable of fluid, competent speech.

  • They may talk in long, nonsensical,

  • yet grammatically correct sentences.

  • - [Dr. Tan] There's a white matter highway

  • between Broca's area and Wernicke's area called

  • the arcuate fasciculus that can be communicates

  • between the two.

  • And so sometimes when there's impact to that,

  • there's something called conduction aphasia

  • where our expression is intact,

  • our comprehension is intact,

  • but because we can't integrate the two,

  • then it's hard for us to repeat language that we hear.

  • - In other cases, extensive deterioration of the brain,

  • such as various types of dementia,

  • can lead to global aphasia

  • where all three factors,

  • fluency, understanding, and repetition are impaired.

  • And what kind of treatments are available

  • for people who are experiencing aphasia?

  • - Our main treatment for the aphasia specifically

  • usually focuses on rehabilitation

  • in the form of speech and language therapy.

  • We always want to have supportive treatments in place

  • for some of the side effects.

  • Individuals with aphasia

  • or at risk for things like depression and social isolation,

  • you know, our brains deteriorate faster

  • with the absence of social connection,

  • so it's really important for individuals with aphasia

  • and for those supporting them to find,

  • you know, alternate ways to communicate with them

  • and continue to integrate them socially.

  • And just making sure that we're patient with them

  • as they try to find the words.

  • - We know that the brain changes

  • over the course of our lives

  • and it generally comes to maturity

  • in the mid to late twenties.

  • During childhood, our neuroplasticity,

  • or the ability of networks in the brain

  • to grow and change,

  • is at its highest levels.

  • - If, for example, children have seizures on the left side,

  • there's this crowding effect

  • that we sometimes observe

  • where language kind of reorganizes

  • onto the right side of the brain to preserve itself

  • and sometimes crowds out the other functions

  • that were typically associated with the right side.

  • So sometimes resulting in weaknesses

  • to non-verbal and visual skills.

  • - So is the brain prioritizing language

  • above significant other functions in general?

  • Is that something that the brain generally prioritizes?

  • - Yes, the brain does tend

  • to try to preserve language abilities.

  • You know, language is so important

  • to be able to communicate,

  • to learn, to navigate the world socially.

  • The brain will reorganize however it can

  • to make sure language function is preserved.

  • - Is it possible to improve your neuroplasticity

  • as an adult?

  • - Yeah, sure, there's always ways that,

  • you know, the typical things that our doctors tell us

  • that we never listen to, right?

  • Making sure that we're really taking care of our sleep,

  • our exercise, our diet.

  • Learning a new language is a really great one

  • that really forces our brain

  • to activate all those parts of the brain

  • that are really important for not just language learning

  • but also code switching and executive functioning.

  • - The brain is an incredibly capable and resilient machine,

  • and scientists are learning new things

  • about the brain-language connection every day.

  • What is something you've learned about the human brain

  • over the course of your career

  • that you think everyone should know?

  • - The number one thing I've learned about the brain

  • is just that there's always more to learn about the brain.

  • We've made big, you know, very large strides

  • in terms of understanding how parts of the brain correlate

  • with brain function,

  • but there are just so many answers that we still don't have,

  • and that's just what makes it eternally fascinating to me.

  • - Language is one of the things that makes us human,

  • and because of that,

  • it is invaluable to us as a species.

  • Any loss of language or communication ability is a tragedy.

  • But by the groundwork laid through studying language

  • through the lens of brain damage,

  • we've come to understand the pieces

  • that make up human language,

  • how injury affects them,

  • and how to apply that information

  • to improve the lives of those who are affected.

  • You may also remember from a previous episode

  • that swearing relies just as much

  • on the right side of the brain.

  • So don't expect someone with left-side brain image

  • to swear any left.

  • Left? Oh no! (laughs) (crew laughs)

  • (bright music)

- In early 2022,

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What Brain Damage Reveals About Language | Otherwords

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    林宜悉 發佈於 2023 年 07 月 27 日
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