1. Recent Findings in the Neurobiology & Neuropsychology of Reading Processes -Part D- A. Maerlender, Ph.D. Clinical School Services & Learning Disorders

2. Motor Aspects of Dyslexia

3. 3 Dyslexics often characterized as ‘clumsy’  Difficulty with Static and dynamic balance Ball skills Manual dexterity Gross & fine motor control Production of simultaneous movements Tapping speed Heel-toe walking Accuracy in copying  Can still be reasonably athletic

4. 4 Motor skills, timing and automaticity  Automaticity the last stage of motor skill learning  Allows for better allocation of attentional resources  Skill automatization (motor & cognitive) appears difficult for dyslexic children Can do single tasks such as balance Can consciously compensate but requires greater effort Difficulty with rapid performance, utilizing a range of sub-skills fluently, when demands exceed resources

5. 5 The process of ‘sequencing’  3 components of movement  Timing  Force  Sequencing

6. 6 Inhibitory Deficits  Appear deficient in LD kids  Common inhibitory control deficit  And/or  Functional deficit in ability to allocate appropriate attention to task relevant information

7. 7 Motor Control & Inhibitory Processes  Inhibitory system is key (more than excitory neurons/system): Curbs impulsiveness Attending to 1 task over time Interrupting overlearned responses Decreasing distractibility Over-riding automatic responses such as reflexes Maintaining appropriate levels of arousal

8. 8 Generalized motor deficits  Not just in phonological skills  But see Leggio, below  Clinic children often show difficulty on tasks requiring changes in tempo Walking slowly, drawing a line slowly Difficulty over-riding highly learned responsessoft findings on neuro exams – postural control, reflexes Hard time changing motor routines

9. 9 Nicolson & Fawcett (1999):Results of PET Study (adults)  Compared with controls, dyslexics displayed significantly lower brain activation  2 tasks – learning a sequence  Repeating a learned sequence

10. 10 Results during the prelearned sequence  reduced activation "...in the right cerebellar cortex and the left cingulate gyrus..."

11. 11 Figure 1: Significant differences in activation between control group and dyslexic group for prelearned vs rest comparison (PET)

12. 12 Prelearned vs rest Greater activation for controls R cerebellar cortex L cingulate gyrus (Brodmann 32) Greater activation for dyslexic group No areas of significant difference

13. 13 Results dearning the new sequence  reduced activation in the right cerebellar cortex only

14. 14 Figure 2: Significant differences in activation between control group and dyslexic group for new sequence vs rest condition

15. 15 New vs rest Greater activation for controls R cerebellum Greater activation for dyslexic group L angular gyrus (Brodmann 39) R medial area 9 (Brodmann 9) L superior temporal gyrus R angular gyrus (Brodmann 39)

16. 16 New vs prelearned  Greater activation for controls L middle frontal gyrus (Brodmann 9 and 46) L anterior cingulate  Greater activation for dyslexic group R medial prefrontal gyrus (Brodmann 9) L insula R uncus (parahippocampal gyrus; Brodmann 28 and 36)

17. 17 Consistent with role of cerebellum  timing and patterning of new cognitive programs

18. 18 Consistent with theory  findings add weight to the theory that many dyslexic children have a "...cerebellar deficit that adversely affects the learning of new skills and the performance of automatic, overlearned skills."

19. 19 Phonological Fluency and Cerebellar Function  Phonological grouping is specifically affected in cerebellar patients: A verbal fluency study Leggio, et al, 2000

20. 20 Findings:  cerebellar computing properties are important for strategy development in the linguistic domain cerebellar damage impairs verbal fluency appears to affect phoneme rule performance but spares semantic rule performance