Hubel  Wiesel
Neuronal architecture of mammalian visual system
Visual receptor
Retina Functional organization
Photoreceptors  Rod and Cone
Anatomical Distribution of Rods and Cones
Phototransduction
 
Ganglion Cell : Contrast discrimination
Receptive Field Receptive fields of photoreceptors and their connections. (A) The receptive field center provides a direct...
Receptive field of bipolar cells
Receptive field Responses of retinal bipolar and ganglion cells to darkness and illumination in the receptive field center...
Lateral inhibition mechanism Responses of retinal bipolar and ganglion cells to darkness and illumination in the receptive...
Receptive field of two ganglion cells overlap Two neighboring retinal ganglion cells receive input over the direct path fr...
Ganglion Cells  Characteristics M Cells P Cells Color No Yes Contrast High Low Spatial  Low High Temporal High Low Populat...
 
Central Projections of Retinal Ganglion Cells
Lateral Geniculate Ganglia
Retinal projection to Lateral Geniculate Nucleus
Central retinal pathway
LGN Projection to Occipital Cortex
Occipital lobe
LGN to Visual Cortex projection
Receptive field of a simple cell in the primary visual cortex
Simple cell of visual cortex
Complex Cell
What Primary Visual Cortex do?
Projection of LGN to V1 <ul><li>A, sends a signal to many simple cells, each with different orientations. In this figure, ...
Complex Cells
Retinal image of an object
Significance of Movement Cells
A rough indication of physiological cell types found in the different layers of the striate cortex.
The ocular dominance columns
Ocular Dominance Columns Ocular dominance remains constant in vertical microelectrode penetrations through the striate cor...
 
Ocular Dominance Column input from LGN R L
The overlap and blurring of ocular-dominance columns beyond layer 4 is due to horizontal or diagonal connections.
Orientation column of visual cortex: Optical imaging
Organization of Blobs
Primary Visual Cortex Architecture
Hypercomplex Cells End Stopping cells
V2-3: Assembling simple  features into objects. V1 V2
Binding Problem
Binding Problem
Illusory contour
What we perceive depends not only on the visual image but also on our interpretation of what we see Interpretation based o...
Visual Area Beyond  V2
Evidence for dorsal and ventral pathway
Inferior Temporal neuron response to  Form
Face and Complex Form Recognition ITC
Fusiform face area
Columnar organization of IT area <ul><li>IT has a columnar organization Cells within a column are activated by the same ob...
Central Visual Pathways
<ul><li>AIT  = anterior inferior temporal area;  CIT  = central inferior temporal area;  LIP  = lateral intraparietal area...
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08b vision processing form and shape

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08b vision processing form and shape

  1. 1. Hubel Wiesel
  2. 2. Neuronal architecture of mammalian visual system
  3. 3. Visual receptor
  4. 4. Retina Functional organization
  5. 5. Photoreceptors Rod and Cone
  6. 6. Anatomical Distribution of Rods and Cones
  7. 7. Phototransduction
  8. 9. Ganglion Cell : Contrast discrimination
  9. 10. Receptive Field Receptive fields of photoreceptors and their connections. (A) The receptive field center provides a direct input from the photoreceptors to the bipolar cell, and the receptive field surround provides indirect input from the photoreceptor to the bipolar cells via horizontal cells. (B) 1: Photoreceptor cell; 2: on-center bipolar cell; 3: off-center bipolar cell; 4: on-center ganglion cell; 5: off-center ganglion cell.
  10. 11. Receptive field of bipolar cells
  11. 12. Receptive field Responses of retinal bipolar and ganglion cells to darkness and illumination in the receptive field center.A) Changes in the electrical activity of the photoreceptor and on- and off-center bipolar and ganglion cells when the photoreceptor receptive field center is in the dark. (B) Changes in the electrical activity of the photoreceptor and on- and off-center bipolar and ganglion cells when the photoreceptor receptive field center is illuminated
  12. 13. Lateral inhibition mechanism Responses of retinal bipolar and ganglion cells to darkness and illumination in the receptive field surround. (A) Changes in the electrical activity of the photoreceptor and on- and off-center bipolar and ganglion cells when the photoreceptor receptive field surround is in the dark. (B) Changes in the electrical activity of the photoreceptor and on- and off-center bipolar and ganglion cells when the photoreceptor receptive field surround is illuminated.
  13. 14. Receptive field of two ganglion cells overlap Two neighboring retinal ganglion cells receive input over the direct path from two overlapping groups of receptors. The areas of retina occupied by these receptors make up their receptive-field centers, shown face on by the large overlapping circles.
  14. 15. Ganglion Cells Characteristics M Cells P Cells Color No Yes Contrast High Low Spatial Low High Temporal High Low Population 5% 90% Action Potential Phasic, fast Tonic, slow Function Movement Shape Receptive field Large Small Retinal mapping Periphery Fovea
  15. 17. Central Projections of Retinal Ganglion Cells
  16. 18. Lateral Geniculate Ganglia
  17. 19. Retinal projection to Lateral Geniculate Nucleus
  18. 20. Central retinal pathway
  19. 21. LGN Projection to Occipital Cortex
  20. 22. Occipital lobe
  21. 23. LGN to Visual Cortex projection
  22. 24. Receptive field of a simple cell in the primary visual cortex
  23. 25. Simple cell of visual cortex
  24. 26. Complex Cell
  25. 27. What Primary Visual Cortex do?
  26. 28. Projection of LGN to V1 <ul><li>A, sends a signal to many simple cells, each with different orientations. In this figure, cell A shares its information with 3 simple cells. If there were a simple cell for each 5 deg change in orientation, the same cell A would provide information to 36 simple cells (180 deg/ 5 deg = 36). </li></ul>
  27. 29. Complex Cells
  28. 30. Retinal image of an object
  29. 31. Significance of Movement Cells
  30. 32. A rough indication of physiological cell types found in the different layers of the striate cortex.
  31. 33. The ocular dominance columns
  32. 34. Ocular Dominance Columns Ocular dominance remains constant in vertical microelectrode penetrations through the striate cortex. Penetrations parallel to the surface show alternation from left eye to right eye and back, roughly one cycle every millimeter.
  33. 36. Ocular Dominance Column input from LGN R L
  34. 37. The overlap and blurring of ocular-dominance columns beyond layer 4 is due to horizontal or diagonal connections.
  35. 38. Orientation column of visual cortex: Optical imaging
  36. 39. Organization of Blobs
  37. 40. Primary Visual Cortex Architecture
  38. 41. Hypercomplex Cells End Stopping cells
  39. 42. V2-3: Assembling simple features into objects. V1 V2
  40. 43. Binding Problem
  41. 44. Binding Problem
  42. 45. Illusory contour
  43. 46. What we perceive depends not only on the visual image but also on our interpretation of what we see Interpretation based on our memories modifies what we see. For example if we expect to see the letter m in “exanple” we may not notice that is has been misspelled.
  44. 47. Visual Area Beyond V2
  45. 48. Evidence for dorsal and ventral pathway
  46. 49. Inferior Temporal neuron response to Form
  47. 50. Face and Complex Form Recognition ITC
  48. 51. Fusiform face area
  49. 52. Columnar organization of IT area <ul><li>IT has a columnar organization Cells within a column are activated by the same object. Neighboring columns respond best to objects of a similar shape as in a and b. </li></ul>
  50. 53. Central Visual Pathways
  51. 54. <ul><li>AIT = anterior inferior temporal area; CIT = central inferior temporal area; LIP = lateral intraparietal area; Magno = magnocellular layers of the lateral geniculate nucleus; MST = medial superior temporal area; MT = middle temporal area; Parvo = parvocellular layers of the lateral geniculate nucleus; PIT = posterior inferior temporal area; VIP = ventral intraparietal area.) (Based on Merigan and Maunsell 1993.) </li></ul>

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