Language 2/Hemispheric Specialization Flashcards
What is speech apraxia?
Disorder of motor planning
Specific to planning/coordinating speech sounds
What is dysarthria?
Speech motor disorder affecting muscle control
Poor articulation, slurred speech
What do speech apraxia and dysarthria have in common?
They are both not an aphasia and not a general language disorder
What is alexia?
Inability to read
How does alexia occur?
It is an acquired deficit (neurological damage) usually to VWFA (visual word form area)
What is dyslexia?
Difficulty/Impairment with reading
How does dyslexia occur?
It is a developmental deficit
What is agraphia?
Inability to write
How does agraphia occur?
It is an acquired deficit
What is dysgraphia?
Difficulty/Impairment with writing
How does dysgraphia occur?
It is a developmental impairment
What does left hemisphere damage in adulthood lead to?
Speech and language problems
Where does complex sound become speech?
Heschl’s gyrus (A1)
Speech selective areas
Planum Temporale
What do ECoG electrodes on the STG respond to?
Manner and place of articulation
Evidence for speech selective cortex
What does the ECoG evidence suggest?
- That higher auditory cortex may be coding for phonetic speech features
- Representation or perceptually relevant aspects of speech sounds
What did fMRI studies of reading tell us about the visual word form area (VWFA)?
There was a greater activation for letters than other visual stimuli.
- absent/weaker activation in illiterate adults and dyslexic children
What happens when you disrupt the VWFA?
Leads to deficits in letter and word reading
What did fMRI studies tell us about the development of the visual word form area?
- VWFA doesn’t show preference for words/letter until children learn to read
- It’s already connected to all the language areas
- Connectivity precedes function
What does the vWFA do as far as letters and being engaged in language processing?
It’s robust and specific
Not sensitive to higher-level linguistic features
How is speech engaged in language processing?
Robust and specific
Not sensitive to higher-level linguistic features
How is high-level language engaged in language processing?
Robust and specific
Distributed processing of meaning + structure
What is an N400 response?
ERP response for semantic violations
- prefers incongruent sentences over congruent ones
- Is reduced and delayed in low comprehenders
What is an P600 response?
ERP response for syntactic violations
- EX: The cat will EAT or *The cat will EATING
Where is language typically located?
Left hemisphere
What is anatomical correlation?
65% of brains have larger temporale in left hemisphere (bigger in fetal development)
How do I know which of my hemispheres language is in?
fMRI study or Wada test
What is a Wada test?
- Inject anesthetic into left or right carotid artery
- When injected into hemisphere that processes language, patient loses ability to understand or produce speech for several minutes
What does the right hemisphere do?
- Better visuospatial processing
- Spatial attention (neglect)
- Better face processing (FFA more robust)
- Left motor, left visual field
What does the left hemisphere do?
- More language
- Right motor, right visual field
How do the hemispheres communicate?
Corpus Callosum
What is the corpus callosum?
Giant white matter bundle
What are homotopic connections?
Link areas in corresponding locations across 2 hemispheres
What are heterotopic connections?
Link different areas across the 2 hemispheres
What are ipsilateral connections?
Link same side
What happens if there is damage to the Corpus Callosum?
Split-brain patients
Who was Patient WJ?
Had split-brain surgery
- no change in personality
- could name and describe visual information presented to his left hemisphere, but not right
How do split brain patients behave when “ring” is presented in their right visual field?
Goes to the left hemisphere which is correlated with language then they say “ring”
How do split brain patients behave when “key” is presented in their left visual field?
Goes to the right hemisphere which is not as heavily correlated with language and the patient denies seeing anything but their left hand correctly retrieves key
What happens when there is a partial resection of posterior corpus callosum?
Sensory information isn’t communicated across hemispheres
How are split-brain patients able to complete the task of arranging blocks into patterns?
Left hand (right brain): could arrange easily
Right hand (left brain): failed every time
