1. Visual System: Overview of Visual Pathway

9. optic nerve optic chiasm optic tract

10. optic nerve optic chiasm optic tract

12. V1 lateral view medial view

13. V1 lateral view medial view calcarine sulcus

16. Visual System: Eye

17. Optics of eye

26. 1.Want to see over a huge range of light levels 2.Need a wide visual field 3.Want high resolution image Vision Challenges

27. photoreceptor

28. neurotransmitter release

30. Phototransduction cascade: Several kinds of protein molecules change shape Second messenger (cGMP) gets cleaved Na + channels close Voltage inside photoreceptor goes more negative Neurotransmitter release decreases

31. Pencil-sharpening cascade

32. Phototransduction cascade, key points: Massive amplification of signal Slow Output (transmitter release) is graded

33. neurotransmitter release

34. Phototransduction cascade, key points: Massive amplification of signal Slow Output (transmitter release) is graded Same in cones as in rods

35. CONE PROPERTIES Not very sensitive – daytime only NEVER saturate Good acuity Provide color vision (humans)

36. ROD PROPERTIES Very sensitive – dusk, night Saturate in moderate-bright light Poor acuity No color vision CONE PROPERTIES Not very sensitive – daytime only NEVER saturate Good acuity Provide color vision (humans)

37. Distribution of photoreceptors across retina cross-section through outer segments of rods & cones

38. cone midget ganglion cells bipolar cells

39. Retinal ganglion cells have center-surround receptive fields – why? center surround

40. response stimulus time OFF retinal ganglion cell: receptive field, stimuli, and responses

42. Mach bands

45. Cone photopigments, human

47. cone midget retinal ganglion cells

48. green cone ON midget retinal ganglion cell

49. Retinal ganglion cell receptive fields green on-center green off-center red on-center red off-center blue on-center black & white on-center black & white off-center

50. green cone OFF midget retinal ganglion cell

51. Retinal ganglion cell receptive fields green on-center green off-center red on-center red off-center blue on-center black & white on-center black & white off-center

52. red cone ON midget retinal ganglion cell

53. Retinal ganglion cell receptive fields green on-center green off-center red on-center red off-center blue on-center black & white on-center black & white off-center

54. red cone OFF midget retinal ganglion cell

55. Retinal ganglion cell receptive fields green on-center green off-center red on-center red off-center blue on-center black & white on-center black & white off-center

56. blue-on retinal ganglion cell blue cone

57. Retinal ganglion cell receptive fields green on-center green off-center red on-center red off-center blue on-center black & white on-center black & white off-center

58. green & red cones ON parasol retinal ganglion cell

59. Retinal ganglion cell receptive fields green on-center green off-center red on-center red off-center blue on-center black & white on-center black & white off-center

60. green & red cones OFF parasol retinal ganglion cell

61. Retinal ganglion cell receptive fields green on-center green off-center red on-center red off-center blue on-center black & white on-center black & white off-center

62. Retinal ganglion cell receptive fields green on-center green off-center red on-center red off-center blue on-center black & white on-center black & white off-center 85%

63. Subcortical Visual System: LGN

65. left eye’s visual field

66. right eye’s visual field

67. binocular visual field

72. The visual system is a completely crossed system

73. visual field

76. macaque monkey LGN section through LGN (macaque monkey)

77. retinotopic map in left LGN visual field

78. input from contralateral eye input from ipsilateral eye ON cells OFF cells Each LGN layer contains a unique cell population ??