1. The Visual System

2. ??!

5. Visual Processing at Retina
Graded potential VS
Action potential

6. Visual Processing at Retina
Horizontal VS
Amacrine

7. Visual Processing at Retina
Horizontal
Lateral inhibition and lateral interactions / maintain sensitivity to luminance contrast
Amacrine
Transform changes in light intensity  
Some types are the only pathway to transmits information from photoreceptors to ganglion cells 

8. Visual Processing at Retina
Inhibited Bipolar VS
Activated Bipolar

9. Visual Processing at Retina
Inhibited Bipolar VS
Activated Bipolar

10. Visual Processing at Retina
On Center Ganglionic VS
Off center Ganglionic

16. Ganglionic Cells Subtypes

17. Y X

18. Y X
Position
Receptive field
Details
movement

19. Y X
Position
Receptive field
Details
movement W

20. Lateral geniculate nucleus

21. Lateral geniculate nucleus

22. Lateral geniculate nucleus

23. Lateral geniculate nucleus

24. Lateral geniculate nucleus

25. Magnocellular system
Parvocellular system

26. VISUAL PATHWAY

28. The retinohypothalamic pathway
day/night cycle
Melanopsin ganglionic cells

29. Visual Pathways
The optic nerve has two principle branches

30. Primary visual cortex

32. Ventral “What” pathway

33. Ventral “What” pathway
Carries information about static object properties such as colour, luminance, stereopsis and pattern recognition.
Slow pathway from P-ganglion cells (through laminae 3-6 of LGN, V1) to V2, V4 and inferior temporal cortex

34. Dorsal “Where” pathway

35. Dorsal “Where” pathway
Information about dynamic object properties- motion and spatial relationships
Fast pathway for transient visual signals
Pathway to V1, V2, MT, medial superior temporal and parietal lobe

36. Optics of Vision
Light refraction

37. Optics of Vision

38. Optics of Vision
Refraction power a lens “Diopter” = 1 m / focal length

39. Optics of Vision

40. Optics of Vision

41. Picture Formation
cataracts (opacities in the lens)

42. Picture Formation Lens accommodation Pupil adjustment
Fusion of the two eyes

43. Optics of Vision

44. Optics of Vision

45. Accommodation

46. Accommodation

47. Vision problems
Ametropia : refraction error, inabiulity of properly focusing light on the retina, a frequent reason for reduced visual acuity

48. Vision problems

49. Accommodation
Presbyopia: Loss of accommodation by the lens

50. Accommodation
Presbyopia: Loss of accommodation by the lens

51. Vision problems
Astigmatism : irregular curvature of either the cornea or the lens, which lead to blurred or distorted vision due to parts of the image are out of focus.

52. Accommodation and parasympathetic
The pupil near reflex

53. Pupillary Adjustment

54. Pupillary Adjustment