Lack of sleep - Lack of learning in Williams Syndrome? INTERNATIONAL WILLIAMS SYNDROME SYMPOSIUM 25th June 2005, Fonyod Department of Cognitive Science Budapest University of Technology and Economics Ilona Kovács, Budapest U. of Technology Gábor Pogány, Budapest U. of Technology Ákos Fehér, Rutgers U., USA Petra Kozma, Retina Foundation, USA
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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 - PowerPoint PPT Presentation
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Lack of sleep- Lack of learning in Williams Syndrome?
INTERNATIONAL WILLIAMS SYNDROME SYMPOSIUM25th June 2005, Fonyod
Department of Cognitive Science
Budapest University of Technologyand Economics
Ilona Kovács, Budapest U. of TechnologyGábor Pogány, Budapest U. of TechnologyÁkos Fehér, Rutgers U., USAPetra Kozma, Retina Foundation, USA
Reiss et al, J Cog Neurosci volume 12 Suppl 1
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
Primary visual cortex (V1)
Local input analysis:• L contrast (1 yr)• disparity (4 mo)• motion (2 mo)• color (2 mo)• orientation
newborn 1mo 2 mo 3 mo 6 mo adult
Teller, 1997
Campbell-Robson CSF Chart
Local cortical filters in V1
On multiple scales
D > 1 D < 1
D = noise spacing / contour spacing
(Kovács and Julesz, PNAS, 1993)
Contour integration in 3-month-olds:
• 60 infants, operant conditioning• poor contour integration• lack of global integration (closure)
behaviorally relevant degree of plasticity is retained in the adult mammalian cortex
perceptual learning in WS
• abnormalities in the occipital lobe• sleep disorders• lack of visual skill learning
color defined card
• lack of closure superiority
• poor contour integration
contour integration in 3-month-old babies
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
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: 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 connectivity is immatureis immature
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.
1 mo 2 mo 3-6 mo 7-9 mo > 9 mo
(Knaap and Valk, 1990)
Stages of myelination
(Thompson et al, 2000)
Growth patterns in the developing brain
visual development: should follow the maturational pattern of participating cortical structures
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
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 alterations in 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)
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?