Neural Substrates of Language/Language Acquisition
How early are children beginning the process of language acquisition?
What is the emphasis of the classic model?
The structures around the sylvian fissure in the perisylvian zone in the dominant hemisphere, which is usually the left hemisphere. Focusing on Broca's area, Wernicke's area, the arcuate fasciculus, which interconnects the two-- it's a white matter tract-- as well as the angular and supramarginal gyri
What is the most severe type of aphasia?
Global aphasia
What are the Brodmann's area numbers for Broca's area and Wernicke's area?
Broca's: BA 44-45
Wernicke's: BA 22
T/F: Aphasia itself involves memory and cognitive deficits
False! (these conditions can co-occur with aphasia, but they are not part of pure aphasia)
T/F: Children under 3 can recognize speech errors.
True!
What is the dual stream model named for?
The two pathways for language (dorsal, thge "where" and ventral, the "what") that are associated with semantic and syntactic processing
What is the trio of more common classifications of aphasia (as opposed to all of the specific categories covered in this unit)?
Expressive/receptive/mixed (a combination of the first two)
For what is Broca's area specifically responsible?
Processing phonology, grammar (morphology, syntax)
Name three potential impairments of language associated with aphasia.
production, comprehension, naming/lexical retrieval, repetition, reading and writing
Which area of the brain is responsible for understanding the syntax and form of language? Which area is responsible for recognition/comprehension of language that we hear?
1) Broca's area
2) Wernicke's area
Walk through the classical model's approach to repetition.
1) Hear something that we want to repeat in the auditory cortex.
2) Information is sent to Wernicke's area, where we recognize what that linguistic form is that we want to repeat.
3) That linguistic form is then sent to Broca's area for the organization of the sounds that we need, or the words, or the morphology, the syntax that we want to use to repeat that form.
4) That information is sent to the motor cortex in order to plan the movements, and send that initiating motor signal down to the articulators to physically repeat what we've heard.
Summary: auditory cortex --> Wernicke's area --> Broca's area --> motor cortex
Name the four types of nonfluent aphasia.
Broca's, transcortical motor, mixed transcortical motor, global
For what is Wernicke's area specifically responsible?
Recognition/interpretation of auditory-linguistic stimuli; "language comprehension" area
T/F: With aphasia, routinized, overlearned language and singing cannot be preserved.
False! Expressions, pause fillers, expletives, idioms/proverbs, etc. as well as singing may be preserved due to the potential of their processing/production being located in a different area of the brain than that which can be affected by aphasia.
The parietal lobe contains a specific area implicated in language. What is the lobule called and what is it responsible for?
Reading, writing, and spelling are implicated in the left hemisphere's inferior parietal lobule (specifically containing the angular and supramarginal gyri).
What important brain structure is left out of the classical model?
The basal ganglia! (And its role in "automatic" language)
Name the four types of fluent aphasia.
Anomic, conduction, transcortical sensory, Wernicke's
Which part of the brain is implicated in accessing of familiar language such as phrases, rhymes, prayers, "automatic speech"?
Basal ganglia
Name three potential causes of aphasia.
1) cerebrovascular pathology (i.e. stroke)
2) Traumatic brain injury
3) Neoplastic conditions (conditions causing tumor growth)
4) Degenerative disease
5) Diffuse brain damage
Which area of the frontal lobe is responsible for naming and lexical retrieval?
Extrasylvian frontal lobe
Why should we take the classical model with a grain of salt? List three reasons.
1) Focuses on cortex and neglects influence of subcortical regions
2) Focuses on only two main "regions" associated with language
3) Limited spacial support given knowledge about neural connectivity - does not fit with current research findings well
What is the hallmark trait of conduction aphasia?
POOR repetition
In what area of language is the thalamus implicated?
Word finding/lexical retrieval, monitoring of language (working together with cortex and basal ganglia)
In the classical model, in what type of lesion is repetition impaired? In what type is it still preserved?
Perisylvian lesion = IMPAIRED repetition
Extraperisylvian lesion = PRESERVED repetition