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Lack of sleep - Lack of learning in Williams Syndrome?

Department of Cognitive Science. Budapest University of Technology and Economics. INTERNATIONAL WILLIAMS SYNDROME SYMPOSIUM 25th June 200 5 , Fonyod. Lack of sleep - Lack of learning in Williams Syndrome?. Ilona Kovács, Budapest U. of Technology

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Lack of sleep - Lack of learning in Williams Syndrome?

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  1. Department of Cognitive Science Budapest University of Technology and Economics INTERNATIONAL WILLIAMS SYNDROME SYMPOSIUM25thJune 2005, Fonyod Lack of sleep- Lack of learning in Williams Syndrome? Ilona Kovács, Budapest U. of Technology Gábor Pogány, Budapest U. of Technology Ákos Fehér, Rutgers U., USA Petra Kozma, Retina Foundation, USA

  2. Reiss et al, J Cog Neurosci volume 12 Suppl 1

  3. area 17 histometric results:signs of abnormal connectivity • Cell measures differ in peripheral visual cortical fields of WS • Smaller, more tightly packed cells in most layers on the left side • Cell packing density and neuronal size differences may be related to visual spatial deficits in WS Galaburda and Bellugi, J Cog Neurosci vol 12 Suppl 1

  4. Primary visual cortex (V1) • Local input analysis: • L contrast (1 yr) • disparity (4 mo) • motion(2 mo) • color (2 mo) • orientation

  5. Campbell-Robson CSF Chart newborn 1mo 2 mo 3 mo 6 mo adult Teller, 1997

  6. Local cortical filters in V1 On multiple scales

  7. D > 1 D < 1 D = noise spacing / contour spacing

  8. (Kovács and Julesz, PNAS, 1993)

  9. Contour integration in 3-month-olds: • 60 infants, operant conditioning • poor contour integration • lack of global integration (closure) (Gerhardstein, Kovács, Ditre, Fehér Vision Research, 2004)

  10. contour integration card test

  11. Contour integration in children (Kovács, Kozma, Fehér, Benedek, PNAS, 1999) D • 510 children, 60 adults • Surprisingly slow curve!! 5-6 y 6-7 y 9-10 y 10-11 y 13-14 y 19-30 y D = noise spacing / contour spacing

  12. contour integration in children: • cue specific (no transfer of learning across orientation and color): visual immaturity (not the lack of attention or motivation) • dependent on contour spacing: limited cortical connectivity?

  13. limited cortical connectivity in children • long axonal connections in V1 • Burkhalter et al, 1993: late maturation of V1 superficial layers horizontal, and V2-V1 feedbackconnections in humans

  14. Reiss et al, J Cog Neurosci volume 12 Suppl 1

  15. area 17 histometric results:signs of abnormal connectivity • Cell measures differ in peripheral visual cortical fields of WMS • Smaller, more tightly packed cells in most layers on the left side • Cell packing density and neuronal size differences may be related to visual spatial deficits in WMS Galaburda and Bellugi, J Cog Neurosci vol 12 Suppl 1

  16. 6 yr 7 yr 10 yr 11 yr 14 yr 30 yr contour integration in Williams Syndrome • with • C. Pleh, A. Lukacs M. Racsmany • Technical U., Budapest • P. Kozma • Rutgers U., NJ 0.6 0.65 0.7 0.75 0.8 0.85 0.9 • poor contour integration • poor orientation discrimination • lack of oblique effect

  17. visual skill (‘procedural,’ ‘habit’) learning 0 º 11-12º • shape identification task • orientation jitter • 5 practice sessions • (30 minutes each) 23-24º with P Kozma, and A Feher Rutgers University

  18. Day 1. C Day 1. W Day 3. C Day 3. W Day 5. C Day 5. W Day 7. W

  19. Texture discrimination task • Karni & Sagi 1991: • specific to quadrant • specific to horizontal • background bars • specific to eye • slow improvement • sleep-dependent • Scwartz et al, 2002: • fMRI; training-dependent monocular increases (V1)

  20. Basic skill (implicit, procedural) learning : • Time-course of learning (behavioral studies) • Plastic changes in the brain (imaging) behaviorally relevant degree of plasticity is retained in the adult mammalian cortex

  21. perceptual learning in WS • abnormalities in the occipital lobe • sleep disorders • lack of visual skill learning

  22. color defined card

  23. contour integration in 3-month-old babies • lack of closure superiority • poor contour integration

  24. Professional musicians - a good model to investigate plastic changes in the human brain • Complexity of stimulus • Extent of exposure • Two steps: • fast initial phase • consolidation, and • gradual increase in • performance • Anatomical changes • Planum temporale • Anterior corpus callosum • Primary hand motor and somatosensory • Cerebellum

  25. visual development “Things start out badly, then they get better; then, after a long time, they get worse again.” (Movshon’s general law on visual development, Teller & Movshon, 1986)

  26. visual development: should follow the maturational pattern of participating cortical structures • connectivity supporting low-level • spatial integration is immature • connectivity supporting the switch • between perceptual interpretations is • immature • top-down connectivityis immature

  27. visual development “Things start out badly, then they get better; then, after a long time, they get worse again.” (Movshon’s general law on visual development, Teller & Movshon, 1986) Visual development is not a homogeneous process. It might be possible to map it in terms of the maturational pattern of cortical connectivity.

  28. Stages of myelination 1 mo 2 mo 3-6 mo 7-9 mo > 9 mo (Knaap and Valk, 1990)

  29. Growth patterns in the developing brain (Thompson et al, 2000)

  30. visual development: should follow the maturational pattern of participating cortical structures

  31. Patient H.J.A. (Humphreys and Riddoch, 1984, 1987b; Riddoch and Humphreys, 1987a) • posterior cerebral artery stroke • bilateral lesions of the occipital lobe extending anteriorly towards the temporal lobes • dense visual agnosia • prosopagnosia • alexia without agraphia • achromatopsia • topographical impairments MRI (1989) : bilateral lesions of inferior temporal gyrus, lateral occipitotemporal gyrus, fusiform gyrus, lingual gyrus (Riddoch et al, Brain, Vol. 122, No. 3, 1999)

  32. Eric R. Kandel – Nobel in 2000; signal transduction in the nervous system • Two steps in synaptic plasticity • short-term memory (protein phosphorylation in synapses) • long-term memory (protein synthesis, which can lead to alterationsin shape and function of the synapse) • The switch from short- to long-term memory • requires gene expression. • (modification of chromatin structure, chromatin is the • DNA-protein complex that constitutes chromosomes)

  33. Switch from short- to long-term memory in humans • Animal models are limited in terms of stimulus • complexity and the duration of training. • Not clear how mechanisms governing synaptic plasticity • at the cellular level are related to the flexibility of operations • seen for large-scale neuronal networks. • Big questions: • Is there plasticity in the adult brain? • Are more complex functions relying on the same • mechansims of learning?

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