Class_07_Reading and Writing Flashcards
Perisylvian language system
- language processing
- phonological processing
- working memory
- reading and spelling
Agraphia
Impairments of writing
- Exner’s area just above Broca’s area on the left hemisphere
- Part of the left perisylvian system
- disorders of spelling (except Chinese)
2 Locations of Alexia
- Angular gyrus, located next to Wernicke’s area
- The Visual Word Form Area as part of the ventral ‘what’ pathway of visual processing
Location of Static word recognition
the visual word form area
Recognizing strokes to write words
Exner’s area
Degeneracy
The same function can be achieved by different systems
- Reading
Degeneracy of Reading
- Occipitotemporal sulcus, the visual word form area
- Word recognition - Motor cortex
- Articulation
Putamen
Moderator of activation between areas related to word recognition
and articulation
- grey matter deep inside the brain, and part of the basal ganglia
- a back-up system if one route is damaged
Pure Alexia
a selective impairment of reading words
- not involving a general agnosia, nor dysgraphia
- ***impaired recognition of word forms
- letter-by-letter reading
- a word length effect
+ longer words will take more time
Location & Cause of Pure Alexia
- left ventral occipito-temporal cortex and visual word form area damage
- stroke in the posterior cerebral artery
Tests for Pure Alexia
- array tests using words
- timed text reading
Hemianopic Alexia
Loss of one side of vision
- half of the fixated word will be unavailable during fixation
- and worse, reading left to right will not help with this as each word fixated is difficult to read
- macular sparing reduce reading impairments
Hemianopic Vs. Pure Alexia
Word length slows down reading
- Pure alexia > Hemianopic alexia
Test for Reading Speed
Silly Sentences Test
- from Speed and Capacity of Language Processing test (SCOLP)
- e.g. “Grapes are people”
Cognitive Models of Reading and Spelling
- Lexical route
- Phonological lexicon -> Lexicon semantics -> Orthographic lexicon - Sub-lexical route
- Grapheme-phoneme conversion
Tests for Lexical Route
- Reading and then pronunciation of irregular words
- National Adult Reading Test
- Weschler Test of Adult Reading
- Test of Premorbid Functioning - Lexical decision tasks
- Spot-the-Word Test from the Speed and Capacity of Language Processing Test
Tests for Sub-lexical Route
asked to read pseudowords aloud
Phonological Agraphia
Difficult SPELLING words that they have heard
- left perisylvian region damage
- impaired on reading pseudowords
- bad spelling through lexical routes
- impaired sub-lexical processing
Phonological Dyslexia
Difficulty READING aloud pseudowords
- left perisylvian region damage
- impaired sub-lexical route
- central phonological impairment
-> dysgraphia and dyslexia
Double Dissociation between Dysgraphia with Alexia/Dyslexia & Pure Alexia
impairment was not with the lexical or lexical routes
- but in some late processing that is specific to written (but not oral) spelling
Dysgraphia
Disordered writing or spelling both oral and written
Neglect dysgraphia
Spelling out loud errors at the beginning of words
- both forward and reversed
- right hemisphere lesion caused by stroke
Micrographia
write a sentence, the size of the text becomes smaller towards the end
- early sign of Parkinson’s disease
Parkinson’s Disease
- loss of dopamine cells in the substantia nigra, part of the basal ganglia
- corticostriatal circuits impairment -> motor symptoms such as tremor and gait freezing
- Akinesia
Corticostriatal Circuits
Link the cortex though the thalamus and basal ganglia.
- Receive projections from the cortex and eventually project back to the same area of cortex
- The motor route (through the putamen) makes a circuit with the
motor cortex
Akinesia
Impairment of generating and providing sufficient force for voluntary movements.
- Gait freezing
- Micrographia
