Module 39 - Speech & Language Flashcards
What is lateralization?
It is defined as localization of function or activity on one side of the body in preference to the other.
If you think of it in terms of our brain, our brain is made up such that each side has a preference for certain functions
What is a visual example of the lateralization of the brain?
How the right side of our brain is set up to pay attention to the world.
Therefore a lesion to the right hemisphere would cause contralateral (left) neglect.
What are the dominant hemisphere functions?
- ***Dominant = usually the left
- Language
- Skilled motor formulation (praxis)
- Arithmetic: sequential and analytical calculating skills
- Musical ability: sequential and analytical skills in trained musicians
- Sense of direction: following a set of written directions in sequence
What are the nondominant hemisphere functions?
- ***Nondomimant = usually the right
- Prosody (emotion conveyed by tone of voice)
- Visual-spatial analysis and spatial attention
- Arithmetic: the ability to estimate quantity and to correctly line up columns of numbers on the page
- Musical ability: in untrained musicians, and for complex musical pieces in trained musicians
- Sense of direction: finding one’s way by an overall sense of spatial orientation
Which hemisphere is usually responsible for visual-spatial analysis and spatial attention?
Nondominant = right hemisphere
Which hemisphere is usually responsible for skilled motor formulation (praxis)?
Dominant = left hemisphere
What are some of the parietal lobe deficits that we’re able to indicate that the left side of the brain is responsible for those actions?
- Apraxias → inability to perform a particular movement even though there is no paralysis (e.g. combing hair)
- Abstract reasoning: e.g telling time, math, reading
- Astereognosia: inability to identify an object from touch (“stereo” – 3 dimensions)
RECALL→ What type of deficits are seen with left diencephalic lesions?
Verbal memory deficits
RECALL → What type of deficits are seen with right diencephalic lesions?
Visual-spatial memory deficits
Are aspects of language represented on both sides of the brain? If yes, what is the left side of the brain responsible for, and what is the right side of the brain responsible for?
Right side = Prosody (emotion conveyed by tone of voice)
Left side = language
What type of deficits do we see with a left MCA (middle cerebral artery) stroke?
Speech is often affected by this type of stroke
Deficits in language
What are the two primary/main areas of the left hemisphere that language processing is accomplished?
- Broca’s area
- Wernicke’s area
- Other areas participate as well (frontal and parietal cortex, etc.)
True or false: analogous regions (from Broca’s area and Wernicke’s area) in the right hemisphere add emotional coloring to language (inflection, etc.) - prosody.
TRUE
Left hemispheric damage can result in a wide variety of language disorders… Give a few examples.
- Broca’s (expressive) aphasia
- Wernicke’s (receptive) aphasia
- Other disorders reflect complex interactions between brain regions responsible for language processing
- Transcortical motor aphasia
- Transcortical sensory aphasia
What does it mean that there is localization within lateralization… use language and the left side of the brain as an example to explain.
- We know that language is lateralized to the left side of the brain, but there are local areas in that left side of the brain that are especially important for explicitly verbal aspects of human language.
- There are two regions in the frontal and temporal association cortices that are important for that →
- Broca’s area
- Wernicke’s area
Where is Broca’s area located and what is the main function?
- Broca’s area = Broadman 44 & 45
- Main function = production of language
- The back end of the frontal lobe
Where is Wernicke’s area located and what is the main function?
- Wernicke’s area = Broadman 22
- Main function = comprehension of language
- The back end of the temporal lobe
Identify the following structures on an image of the left hemisphere:
Primary motor cortex
Primary somatic sensory cortex
Primary visual cortex
Primary auditory cortex
Broca’s area
Wernicke’s area
IMAGE
What are the 3 main functions of the right hemisphere?
Visual-spatial
Attention
Emotion
Is the left hemisphere always the critical player for language or some people are different?
There is about 5- 10 % of people that are a little different (maybe not even that much), but for the focus of the class → left hemisphere = language
Is the left hemisphere responsible for the movement of the tongue and the lips to speak?
- NO, Left-sided language organization is distinct from the circuitry concerned with the motor planning and control of the larynx, pharynx, mouth, and tongue.
- The left hemisphere is responsible for the higher-level function of language
- We are talking about all languages → English, French, Spanish and even sign language
***Disclaimer***
Any “localized” cortical functions depend on diffuse brain networks, involving not only cortical structures but subcortical structures as well (and the connections between these areas!)
Do “localized” cortical functions depend only on cortical structures? If yes, explain. If no, explain.
Any “localized” cortical functions depend on diffuse brain networks, involving not only cortical structures but subcortical structures as well (and the connections between these areas!)
Is there a variability of language representation in the brain?
- There is some variability in language representation.
- You can see in the image that a % of patients where stimulation of other areas out of Broca’s area and Wernicke’s area will interfere with speech.
- But the highest % of patients will show correlation with Broca’s and Wernicke’s area
What is the important structure for language production and what does it do?
Broca’s area → activates particular sequences of sounds to produce words and sentences
What is the important structure for language comprehension and what does it do?
Wernicke’s area → identifies and comprehends particular sequences of sounds as meaningful words
What connects the Broca area with the Wernicke area?
The arcuate fasciculus
What are some characteristics of Broca’s aphasia?
Halting speech
The tendency to repeat phrases or words (perseveration)
Disordered syntax
Disordered grammar
Disordered structure of individual words
Comprehension intact
What are some characteristics of Broca’s aphasia?
Fluent speech
Little spontaneous repetition
Syntax adequate
Grammar adequate
Contrived or inappropriate words
Comprehension not intact
Which part of the brain light up and why with each of these scenarios (look at the image)?
- When the person is passively viewing words –> the primary visual cortex lights up. This makes sense because the person is just looking at it.
- When the person is listening to the words –> you start to see Wernicke’s area lighting up. This area is for reception, listening and understand what has been said.
- When the person is reading and speaking the words –> you can see that the arcuate fasciculus lights up. This is generation.
- When the person actually has to generate the words that associate with it -> you can see that the Broca’s area lights up
- This experiment is important since it demonstrates the following:
- Common language tasks involve Broca’s and Wernicke’s area, as expected.
- Also, involve primary and association motor and sensory areas.
Language depends on a network of cortical (and subcortical) areas.
Are there different regions to store information about different objects/concepts?
- YES, there are similar cells like the ones that are able to recognize faces, these cells are responsible for recognizing words.
- There is a different activity in language areas when listening to words in different groups
- Lesions can lead to language difficulties (e.g. naming) within a single category of objects.
With congenital hearing loss, does sing language develop naturally in deaf infants?
- Yes, sign language still uses the same functional areas in the brain as if it was a normal language.
- This graph demonstrates two groups, the heating infants and deaf infants, what we see is that the deaf infant’s meaningful hand gestures increased as their ability to use their hands increased.
- Much like when hearing infants babble when they are quite young, deaf infants babble with their hands and they start to make these precursor gestures that ultimately grow into fluent sign language.
- The manual babbling in hands is therefore much more increased in deaf infants compared to hearing infants.
What does a left-sided stroke causes in deaf individuals?
“Sign” aphasia
What does a right-sided stroke cause in deaf individuals?
Decreased “emotion” in signing
What are some examples of disorders that are commonly mistaken for aphasia?
- Disorders of speech production
- Dysarthria
- Aphemia
- Mutism
- Auditory disorders
- Peripheral hearing loss
- Pure word deafness
- Cortical deafness
- Defects in arousal and attention
- Global confusion state
- Narcolepsy
- Psychiatric disorders
- Schizophrenia
- Conversion disorder and other somatoform disorders
- Uncooperative patient
What are the different types of aphasia?
IMAGE
What basic areas would need to be activated, and in what order, to read a word and repeat it out loud?
Image!
