Dyslexia Flashcards
What is orthography?
Conventional spelling system of the language
What is phonemic structure used for?
Symbols can be translated into correct sounds
What is visuomotor integration that dyslexics have problems?
What the eyes see has to be integrated with motor signals from the eye movement the eye movement system
What is the visual control of the eye movement system dominated by?
A network of large neurons known as magnocellular system
Where is the magnocellular system?
It can be traced right from the retina through the pathway to the cerebral cortex and cerebellum to the motor neurons of the eye-muscles
What is the magnocellular system specialised to do?
Respond to moving stimuli
What is magnocellular system important for?
Tracking moving targets
What is an important feature of the magnocellular system?
Generating motion signals, during reading when eyes move off letter they are meant to be fixating, the motion error signal is fed back to the eye-movement system to bring eyes back on target
What is the magnocellular system important for?
It is important for helping to point the eyes steadily at each letter to determine their order
What is mildly impaired in many dyslexics?
Visual magnocellular system
What is different in dyslexics?
Sensitivity to visual motion is poorer than normal readers and their brain wave responses to moving stimuli are abnormal, brain imaging has also revealed altered patterns of functional activation in regions sensitive to visual motion, control of the eye is also less steady
What is phonemes?
Letter sounds
How do we distinguish phonemes?
Detecting subtle differences in sound frequency and intensity changes that characterise them
How do we detect sound changes?
System of large auditory neurons that track changes in sound frequency and intensity
What other factors can cause dyslexia?
Impaired development of brain cells, problems in neurons that from frameworks throughout the brain that seem to be specialised for tracking temporal changes, cells all have the same surface molecule by which they recognise and form contacts with each other but may be vulnerable to antibody attack
