The document discusses the anatomy and physiology of the visual system, including: - The retina contains rod and cone photoreceptors which detect light and have receptive fields. - Ganglion cells in the retina receive input from overlapping photoreceptors and send signals to the lateral geniculate nucleus in the thalamus. - The primary visual cortex, also known as V1, contains cells that respond to features like orientation, motion, and color. Signals from V1 are sent to extrastriate visual areas for further processing.

2. Visual receptor

3. Neuronal architecture of mammalian visual system

4. Retina

5. Photoreceptors Rod 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 Cells Stimulus M Cells P Cells Color No Yes Contrast High Low Spatial Low High Temporal High Low

19. Ganglion Cell : Contrast discrimination

21. Central Projections of Retinal Ganglion Cells

22. Lateral Geniculate Nucleus

23. Lateral Geniculate Ganglia

25. Pupillary reflex

26. Organization of Visual Cortex

27. Extrastriate Visual Areas Macaque Monkey

28. Human Visual Cortex fMRI

31. Visual Cortex Architecture

32. Visual Cortex Architecture

33. Recording from Visual Cortex

35. Simple cell of visual cortex

36. Simple Cell

37. Complex cell

38. Complex Cell

39. Complex Cells

40. Hypercomplex Cells

42. Significance of Movement Cells

43. Orientation Column

45. Orientation column of visual cortex

46. Illusion of Edges: V2 in Monkey

47. Inferior Temporal neuron response to Form

49. Illusion of Edges: V2 in Monkey

50. Face and Complex Form Recognition ITC

51. Blobs 40μm 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

54. Visual Cortex Architecture

56. 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.)

57. Motion in the visual field

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 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.)

65. MT lesions in Monkey and Man with altered Motion Perception

66. Inferior Temporal neuron response to Color & Form

67. Color Vision

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 Protanope Deuteranope Tritanope

77. Ishihara Chart for Color blindness testing 21, 2