Disorders of Language Flashcards
What is the Wernicke-Lichtheim-Geschwind model?
- Words are perceived through a specialized word centre (Wernicke’s area) in the left temporoparietal junction
- Projects to word production centre (Broca’s area) located in the left inferior frontal gyrus
What are the two broad streams of language processing? (after the superior temporal gyrus)
- Ventral comprehension network: Connected via inferior occipito-frontal fasciculus
- Dorsal speech production pathway: Associated with arcuate fasciculus
What are the connections of the auditory dorsal stream?
- Connects auditory cortex to parietal lobe and inferior frontal gyrus
What is the function of the auditory dorsal stream?
- sound localization
- speech production
- speech recognition
- vocal mimicry
- lip reading
- phonological WM
- LTM
What are the connections of the auditory ventral stream?
- Connects auditory cortex to middle temporal gyrus and temporal pole which projects to inferior frontal gyrus
What is the function of the auditory ventral stream?
- Extracting meaning from sound
- Maintenance of perceived sound objects in WM
- Sentence comprehension
Which auditory stream has evidence for bilateral processing?
- ventral
Compare Broca’s and Wernicke’s patients.
Broca:
- Production impaired but comprehension intact
- Often had right hemiparesis (weakening of right arm and leg)
Wernicke:
- Fluent, but nonsensical sounds, words, sentences
- Damage to posterior region of superior temporal gyrus
What is the modern view of language production?
- Involves “task positive” systems: linguistic processes, motor and sensory systems, controlled access to semantic representations
- Includes both domain-specific networks (language-specific) and domain-general networks (mediating top-down and bottom-up attentional control)
- May include “task negative” systems involved in accessing semantic and episodic memory
What are the 3 networks involved in language production?
- Frontotemporoparietal network (LH): Includes left paracingulate cortex, left lateral frontal cortex, and left superior and inferior parietal lobules
- Activated during speech but not during count and decision trials - FTP network (RH): Activated during count and decision trials but not during speech
- FTP (LH, overlapping): Shows deactivation during speech
What is the Wada test? What did it reveal about handedness?
- While patient is awake, barbiturate is introduced not internal carotid arteries in order to shut down language / memory function in one hemisphere
- Patient engages in a series of language and memory tests: Memory is evaluated by showing patient a series of pictures. Once it wears off, patient is tested on recall.
- For patients without LH lesion, both right handed and left handed patients have speech more greatly represented in LH. However, left handers also sometimes have speech represented in the RH or bilaterally moreso than right handers.
- For patients with LH lesions, left handed patients have speech represented in RH more commonly than LH. However, RH still have greater representation in LH.
What are aphasias? What is the difference between primary and secondary aphasia?
- Disorder of language apparent in speech, writing, alexia produced by injuries to brain areas specialized for these functions
- Primary due to problems with language processing mechanism while secondary is due to memory, attention, or perceptual problems
What are the 2 symptoms of disorders of comprehension?
- Poor auditory comprehension
2. Poor visual comprehension
List 8 symptoms of disorders of production.
- Poor articulation
- Word-finding deficit
- Unintended words / phrases
- Loss of grammar or syntax
- Inability to repeat presented material
- Low verbal fluency
- Inability to write
- Loss of tone in voice
Name 5 differences between fluent aphasia and schizophrenia
- Those with fluent aphasia have fluent but short speech. Schizophrenics have extended and rambling speech
- Prosody is intact in fluent aphasia but impaired in schizophrenia
- Content is empty in fluent aphasia, but bizarre and restricted in schizophrenia
- Comprehension impaired in fluent aphasia but intact in schizophrenia
- Reading impaired in fluent aphasia but intact in schizophrenia