Language and amnesia Flashcards
1
Q
What counts as language? (7)
A
- Language is a system of communication
- it uses sounds, symbols (normally visual, but also tactile), and gestures
- it describes the processing of perceptual inputs and motoric outputs
- receptive language : listening (or watching a signer), reading
- productive language : speaking (signing), writing
- the thinking in between?
- defined by grammar/syntax, phonology, orthography
2
Q
What is broken language? (6)
A
- Earliest and most striking insights about functional neuroanatomy of language have come from cases of brain injury
- aphasia (dysphasia) : partial or complete loss of language ability following brain damage
- expressive aphasia; speech motor functioning (e.g., articulation) intact
- receptive aphasia; auditory perception intact
- alexia (dyslexia) : partial or complete inability to read
- agraphia (dysgraphia) : partial or complete inability to write/spell
3
Q
What is Broca’s area? (5)
A
- reported studies of 8 patients with left frontal lobe damage and speech problems
- posterior part of inferior gyrus of dominant (usually left) frontal lobe controls articulate speech
- but they also had right-sided paralysis
Could speak but couldn’t say what they wanted to say - demonstrated both localisation and lateralisation of language function
4
Q
What is Broca’s aphasia? (7)
A
- nonfluent/agrammatic/ expressive/motor aphasia
- can understand speech (mainly…), knows what s/he wants to say
- cognition otherwise intact
- anomia (dysnomia)
- telegraphic speech say the minimal amount of words possible
- mainly content words, few function words, poor use of affixes
- agrammatism
5
Q
What is Wernicke’s area?
A
- aphasia was associated with left hemisphere damage in the superior temporal gyrus
- there was no opposite side paralysis
- patients spoke fluently but did not make sense
- patients could hear but could not understand or repeat
- this syndrome is called Wernicke’s aphasia and the associated region of the temporal lobe (the posterior region of the superior temporal gyrus) is called Wernicke’s area
6
Q
What is Wernicke’s aphasia?
A
- fluent/receptive/sensory aphasia
- can’t understand speech, who knows what s/he wants to say?
- cognition otherwise intact (but hard to test)?
- pressured speech (lots of content)
- syntactically well-formed, but “gibberish”
- many paraphasic errors (incl. neologisms)
- don’t understand why others don’t understand them?
7
Q
What is conduction aphasia? (7)
A
- Lesion affecting fibres of the arcuate fasciculus
- comprehension good
- speech fluent
- difficulty repeating words
- repetition substitutions, omissions
- paraphasic errors
- extreme difficulty repeating function words, nonsense words, polysyllabic words
8
Q
What is aphasia like in bilingual people?
A
- L1 (more fluent, learned earlier) relatively preserved cf. L2
- second language uses partially overlapping neural networks
second language is more vulnerable to damage
9
Q
What is aphasia like in deaf signing people?
A
- patterns of deficit mirror those for spoken language
- Broca’s, Wernicke’s
- again, motoric ability to gesture is intact
- deficits correlate in speaking+signing aphasics
10
Q
How is there cerebral asymmetry in language processing? (6)
A
If show smtg in right vis field, the person can read it (goes to left hemisphere)
If show it to left vis field, cant read it
If give smtg to left hand, cant describe it but can move it
If show smtg to right hemipshere, can draw it
* Left hemisphere language specialisation (“dominance”)
* Right hemisphere specialisation for other functions: spatial analysis, crude language skills (can pick ball)
11
Q
What is the link between anatomical asymetry and language? (5)
A
- May relate to development of handedness (no bias in other primates)?
- Left Sylvian (lateral) fissure is longer, less angled
- Left planum temporale is typically larger (up to 5x!)
- because of language?
- no, because differences exist in utero
- asymmetry allows for language development?
Evolutionary advantage of lateralisation of fction bc our anatomy favors it
12
Q
How do we establish language dominance? (5)
A
- 90% of all people are right-handed
- LH is dominant for 96% right-handers, 70% left-handers
- 93% of people are left-hemisphere dominant
- left-handers are more likely to have mixed dominance
- Wada test
- intracarotid amobarbital injection
- anaesthetises one hemisphere for ~10 mins
- speech arrest
- arm drop
- test comprehension, speech
13
Q
How can we map language areas? (4)
A
- Intraoperative brain stimulation can produce vocalisation, speech arrest, paraphasic errors
- motor areas on both sides : arrest, cries
- LH speech areas : arrest (dose-dependent), anomia, word confusion
*Lots of individual variation
14
Q
How do we use functional imaging to study language? (5)
A
- PET : metabolic activity (radioactive label, low spatial resolution)
- fMRI : activity inferred from blood flow changes (non-invasive, high resolution)
- record during 3 different language tasks (CF, silent reading, story listening)
- activated brain areas consistent with temporal and parietal language areas
- more activity than expected in nondominant hemisphere
15
Q
How do we hear sight and see touch?
A
- deaf Ss “reading” ASL : surprisingly bilateral, auditory areas (STG) very active
they anticipate what they would be doing if they were signing - Braille activates somatosensory cortex
- but also V1
