08a vision processing intorduction

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2. Visual receptor 3. Neuronal architecture of mammalian visual system 4. Retina 5. PhotoreceptorsRod and Cone 6. Anatomical Distribution of Rods and Cones 7. Phototransduction 8. Phototransduction Light Dark 9. Retina Functional organization

  • Retinal cell types
  • Neural Circuitry of Retina
  • Hyperpolarization
  • Neurotransmitters
  • Electrical synapse with graded conduction
  • Lateral inhibition
  • Bipolar cell depolarization/ hyperpolarization

10. Receptive Field An experimental plan for recording from the visual pathway. The animal, usually a macaque monkey, faces a screen onto which we project a stimulus. We record by inserting a microlectrode into some part of the pathway, in this case, the primary visual cortex. (The brain in this diagram is from a human, but a monkey brain is very similar.) 11. Receptive field of Retina 12. 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. 13. 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. Dimension of Receptive field One millimeter on the retina corresponds to 3.5 degrees of visual angle. On a screen1.5 meters away, 1 millimeter on the retina thus corresponds to about 3.5 inches, or 89 millimeters. 15. 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 16. 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. 17. Receptive Field: Ganglion CellsStimulusM Cells P Cells Color No Yes Contrast High Low SpatialLow High Temporal High Low 18. 19. Ganglion Cell : Contrast discrimination 20. 21. Central Projections of Retinal Ganglion Cells 22. Lateral Geniculate Nucleus 23. Lateral Geniculate Ganglia 24. 25. Pupillary reflex 26. Organization of Visual Cortex 27. Extrastriate Visual Areas Macaque Monkey 28. Human Visual Cortex fMRI 29. 30. 31. Visual Cortex Architecture 32. Visual Cortex Architecture 33. Recording from Visual Cortex 34. 35. Simple cell of visual cortex 36. Simple Cell 37. Complex cell 38. Complex Cell 39. Complex Cells 40. Hypercomplex Cells 41. 42. Significance of Movement Cells 43. Orientation Column 44. 45. Orientation column of visual cortex 46. Illusion of Edges:V2 in Monkey 47. Inferior Temporal neuron response toForm 48. 49. Illusion of Edges:V2 in Monkey 50. Face and Complex Form Recognition ITC 51. Blobs

  • 40m thick layer of upper cortex that has been processed histochemically to reveal the density of cytochrome oxidase, a mitochondrial enzyme involved in energy production

52. Ocular dominance column 53. 54. Visual Cortex Architecture 55. 56.

  • AIT= anterior inferior temporal area;CIT= central inferior temporal area;LIP= lateral intraparietal area;Magno= magnocellular layersof 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.)

57. Motion in the visual field 58. 59. PET scan of MT area for Motion Processing 60. Depth of vision 61. Neuronal basis of stereoscopic vision 62.

  • AIT= anterior inferior temporal area;CIT= central inferior temporal area;LIP= lateral intraparietal area;Magno= magnocellular layersof 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.)

63. 64. 65. MT lesions in Monkey and Man with altered Motion Perception 66. Inferior Temporal neuron response toColor& Form 67. Color Vision 68. 69. Cones and Color Vision 70. Surface reflectance 71. Surface reflected from blue vase in sunlight and skylight 72. The reflectance function of a natural surface 73. L+M L-M L+M-S 74. Receptive field of Primate Ganglion Cells for Color 75. The Importance of Context in Color Perception 76. Color blindness Normal ProtanopeDeuteranopeTritanope 77. Ishihara Chart for Color blindness testing 21, 2