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Spatial representation and coordinate frames in the brain

Spatial representation and coordinate frames in the brain. Hemispheric Neglect. Unilateral Neglect: failure to attend to (or represent) sensory information in the left (contralesional) side of space , following right brain parietal injury. Neglect as a deficit in representation.

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Spatial representation and coordinate frames in the brain

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  1. Spatial representation and coordinate frames in the brain

  2. Hemispheric Neglect Unilateral Neglect: failure to attend to (or represent) sensory information in the left (contralesional) side of space, following right brain parietal injury.

  3. Neglect as a deficit in representation • Bisiach & Luzzati (1978): imagining a familiar scene (e.g., central square of Milan), from opposite view points

  4. Parietal lesions in the right hemisphere are commonly associated with left field neglect Yellow: the lesion typically involves the supramarginal gyrus at the temporoparietal junctionRed: variation in the exact extent of the lesionDriver and Mattinagley, NNS, 1998

  5. Common tests for Visual Neglect • Drawing from memory

  6. copying pictures or words

  7. crossing out items

  8. line bisection

  9. reading words

  10. “Burning house”:Implicit processing of the unattended side

  11. Neglect can be in egocentric and/or allocentric reference frames

  12. Egocentric/allocentric neglect

  13. Scene/view/object centered neglect Hillis & Caramazza 1990

  14. SEF neurons show selectivity for saccade direction Olson 2003

  15. An SEF neuron that shows selectivity on bar-left trials regardless of the saccade’s physical direction

  16. Posterior parietal cortex – parietal reach region

  17. Eye position gain fieldsin parietal cortex Andersen et al., 1985

  18. neurons with head centered RF(in VIP) (Duhamel et al., 1997)

  19. Coordinate transformations

  20. Neuronal activity in area 5dependence on eye & hand position fixed eye position fixed hand position 1 sec Buneo et al., 2002

  21. What’s the coordinate system of these neurons?

  22. Target Buttons Initial hand position Initial eye position PRR neuronal activity:Reach Plans in Eye-Centered Coordinates Same eye position Same hand position

  23. optimal target position depends on

  24. Tactile-visual processing in peripersonal space

  25. Peripersonal space-The immediate space surrounding the body (or a certain body part).Extrapersonal space – unreachable.

  26. Integrated visual-tactile coding of peripersonal space, centered on body parts Tactile RF Visual RF Iriki A. et al., Neuroreport 1996

  27. Response of neuron (spike/sec) Stimulus trajectory Representation of visual information in hand-based coordinates 1 2 3 4 1 2 3 4 Tactile RF Visual stimulus trajectory Graziano MS., PNAS 1999

  28. The cell’s response doesn’t depend on fixation position

  29. Neurons with multimodal receptive fields were found in areas: -Ventral premotor -Ventral intraparietal (VIP) -Parietal BA 7b, 5 - Putamen

  30. Postural bimodal neurons in area 5 respond to the seen position of the hand M.S. Grazianoet al., Science (2000)

  31. The effect of the fake arm M.S. Grazianoet al., Science (2000)

  32. The rubber hand illusion It’s mine!

  33. Pointing at my hand? Botvinick and Cohen, 1998, Nature

  34. The rubber hand illusion in the fMRI scanner

  35. The rubber hand illusion

  36. Brain activity - 2 Linear relationship subjective rating of the illusion vs. level of PM activity R2= 0.3969, P<0.003 R2= 0.3982, P<0.002 * Also found in R. cerebellum.

  37. Makin et al 2007

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