Lecture 8: Writing Disorders Flashcards
Types of spelling
- written spelling
- oral spelling
- typing
How do we spell?
- lexical process
- sublexical process
Lexical process
Used to retrieve spelling of known words
Sublexical process
Encodes the systematic relationship between phonemes and graphemes -> used to retrieve spelling for unfamiliar words
Graphemic buffer
Convergence point for lexical and sublexical process
Patient LAT with Alzheimer’s, where is the atrophy?
Temporo-parietal regions
Patient LAT’s writing skills
- more errors for low frequency words
- good spelling of pseudo words and nonwords
Conclusion of LAT
- damage to lexical process
- impairment in the orthographic output lexicon
- forgot the spelling of known words
The cognitive processes of spelling - general
- starts by hearing words
- input: auditory analysis and speech processing
- semantics
- memory
- motor systems: writing, typing…
The cognitive processes of spelling - specific
- central processes
- peripheral processs
Central processes of spelling
- orthographic long-term memory O-LTM
- orthographic working memory O-WM (graphemic buffer)
- phonological-orthography conversion (POC)
Peripheral processes of spelling
- allographic conversion/selection -> written spelling
- letter-name selection -> oral spelling
- graphic-motor planning -> typing
Spelling a familiar word
Retrieving orthographic information from O-LTM
Spelling an unfamiliar word
Generating plausible spellings for unknown words via POC
Spelling a word
After O-LTM or POC, they are processed by limited-capacity O-WM
Function of peripheral processes in spelling a word
Produce letters in specific modality and format and select shapes
Phonological dysgraphia
Severe difficulties with spelling pseudo words
- caused by dysfunctional sublexical processes
- damage of perisylvian cortical regions
Surface/lexical dysgraphia
Difficulties with spelling irregular words
- lesions in the left ventral occipito-temporal cortex and also left anterior temporal lobe and temporal-parietal cortex
Deep dysgraphia
- inability to spell pseudo words -> phonological errors
- produce semantic and lexical substitution errors -> semantic errors
-damage to both lexical and the lexical processes
- large LH
Peripheral dysgraphia
Oral spelling and typing relatively preserved but impairment in handwriting codes
O-LTM impairment
More errors for low- relative to high-frequency words, word-level errors
O-WM impairment
More errors on long relative words, letter-level errors
If POC also damaged
Semantic errors in major difficulties. With spelling unfamiliar words and pseudo words
Neural adaptation
When a neural population is repeatedly engaged, its response diminishes as repetitions increase
