Lecture 14 Language (Layla) Flashcards
Which aphasia is limited to production of mainly verbs and nouns?
Broca’s (Expressive) Aphasia.
have trouble speaking fluently but their comprehension can be relatively preserved. …
difficulty producing grammatical sentences and their speech is limited mainly to short utterances of less than four words.
When did Paul Broca encounter his “area”?
1865
Which area is damaged in Broca’s aphasia?
(area and BA)
Damage to
Inferior frontal gyrus
(BA 44/45)
Broca’s aphasia is nota problem controlling vocal muscles
Why?
It is nota problem related to general intelligence
Why?
Can blow out candles
Clear one’s throat
Scores on non-verbal tests are normal
Calculation, map reading, facial recognition
Can carry out verbal commands
When did Carl Wernicke discover his “area”
1874
Where is wernicke’s area?
left temporal lobe
Which aphasia are patients generally unaware of their deficit?
Wernicke’s
[Loss of ability to comprehend words, speech remains fluent but nonsensical (word salad)]
Where is Wernicke’s area?
It is traditionally thought to be in Brodmann area 22, which is located in the superior temporal lobe in the dominant cerebral hemisphere
percentage of people with left/right hemisphere dominance
the left hemisphere in about 95% of right handed individuals and 60% of left handed individuals).
what is fluent aphasia?
Damage caused to Wernicke’s area results in receptive, fluent aphasia. This means that the person with aphasia will be able to fluently connect words, but the phrases will lack meaning.
What is non-fluent aphasia?
non-fluent aphasia, in which the person will use meaningful words, but in a non-fluent, telegraphic manner.
(Expressive; Broca’s)
Broca’s Aphasia summary
Left frontallobe damage
Speech production deficits
Comprehension spared
Paraphasicerrors of letters and/or words
Wernicke’s Aphasia Summary
Left temporallobe damage
Speech production spared
Comprehension deficits
Severe paraphasicerrors
Neologisms: Not a real word, but sounds like one
e.g.,) biznit, scrut, almod
What is conduction aphasia?
Inability to transfer information between Broca’s and Wernicke’s areas
Arcuate fasciculus –white matter tract connecting Broca’s and Wernicke’s area
Which aphasia is repetition impaired?
Conduction Aphasia
Production is intact (no damage to Broca’s)
Comprehension is intact (no damage to Wernicke’s)
Just Repetition impaired:
disconnect between how sounds map on to words and how to produce those sounds
What is Anomic Aphasia?
Impairment in word-finding and naming
3 types of Anomic Aphasia
(Anomic Aphasia: Impairment in word-finding/naming)
- Word selection anomia
Correctly selects target in group, but cannot name it
- Semantic anomia
Unable to select the correct object from a group of objects, even when provided with the name of the target object
- Disconnection anomia
Modality-specific impairments
What is Transcortical Motor Aphasia?
Similar in presentation to Broca’s Aphasia
Normal (spontaneous) speech production is impaired
Echolalia –compulsion to repeat something just heard
Repetition of words or phrases is normal
TMoA is generally characterized by reduced speech output, which is a result of dysfunction of the affected region of the brain. The left hemisphere is usually responsible for performing language functions, although left-handed individuals have been shown to perform language functions using either their left or right hemisphere depending on the individual.
Transcortical motor aphasia is a rare syndrome that is due to a small subcortical lesion superior to Broca’s area or to a lesion outside of the anterior language areas of the left hemisphere
What is Transcortical Sensory Aphasia?
Similar presentation to Wernicke’s aphasia
Word salad
Paraphasias
Neologisms
Comprehension impaired
Repetition is spared, often see echolalia
Damage to angular gyrus most often, also frontal or thalamic lesions
What is Pure Word Deafness?
Inability to comprehend speech
Hear spoken language as meaningless noise (foreign language)
Reading, writing, speech production, and naming intact
Bilateral superior temporal lobe lesions (some parietal involvement)
2 Routes for Reading
Phonological Method:
CAT = /c/ /a/ /t/
Grapheme-to-phoneme correspondence rules. (graphemes = smallest units of written language, e.g., letters)
“Hukt awn fonix werkt fur me”
Whole-Word Method:
Direct route
Go directly from orthography (the structure of the printed word)to meaning
Irregular words (yacht, colonel) can only use direct route
Whole-Word Method
Aoccdrnigto a rscheearchat CmabrigdeUinervtisy, it deosn’t mttaerin wahtoredrthe ltteersin a wrodare, the olnyiprmoetnttihngis tahtthe fristand lsatltteerbe at the rghitpclae. The rsetcan be a toatlmsesand you can sitllraedit wouthitporbelm. Tihsis bcuseaethe huamnmniddeosnot raederveylteterby istlef, but the wrodas a wlohe.”
Disorders of Visual Language: Alexia
Inability to read following brain damage
Co-occur when there is damage to angular gyrus
Alexia and agraphia are doubly dissociable:
e.g.,) Can write a sentence and unable to read it or can read a sentence but be unable to write it
Disorders of Visual Language: Agraphia
Inability to write following brain damage
Co-occur when there is damage to angular gyrus
Alexia and agraphia are doubly dissociable:
e.g.,) Can write a sentence and unable to read it or can read a sentence but be unable to write it
Phonological Alexia
Inability to map graphemes onto phonemes
No difficulty reading familiar regular words or irregular words, but cannot read unfamiliar words or non-words
E.g., won, one, wun
Inability to map graphemes onto phonemes
Damage to posterior inferior temporal lobe
Surface Alexia
Disruption of ‘whole-word’/sight reading
Impaired reading of irregular words (e.g., one)
Reading of regular words and non-words is preserved (e.g., won, wun)
Damage to the parieto-occipital junction
2 Routes for Writing
Two routes (analogous to reading):
1) Thought to semantics to writing (writing from memory)
2) Grapheme to phoneme correspondence rules (“sounding out” to write)
Phonological Agraphia
Inability to write a word by sounding it out (e.g., non-words or unfamiliar words)
Preserved ability to write both familiar regular and irregular words
Damage to posterior parietal lobe, supramarginal gyrus (near Wernicke’s area) and angular gyrus
Surface Agraphia
Inability to write irregular words (e.g., yacht)
Preserved ability to write regular words or non-words by sounding them out
Damage to parieto-occipital junction
Close to visual cortex (needed to go from word meaning directly to word form)
Presurgical fMRI and DTI
Use fMRI to localize function near the resection
Tool for neuronavigation
Tractography(e.g., DTI) for mapping white
matter tracts
Remove as much affected tissue as possible, while preserving essential functions
Functional Areas of cerebral cortex
Layla’s
Take Home Message
Variety of ways in which language can be altered following brain injuries
E.g.,) Aphasia, alexia, agraphia
Both reading and writing can have impairments to ‘phonological’ or ‘whole-word’ processes
I.e.,) Sounding out vs. sight vocabulary
fMRI and DTI valuable for presurgical planning in patients undergoing neurosurgery procedures
