1. The primate visual systemHelmuth Radrich, 24.06.2004 The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

2. The primate visual systemHelmuth Radrich, 24.06.2004 Visible spectrum

3. The primate visual systemHelmuth Radrich, 24.06.2004

4. The primate visual systemHelmuth Radrich, 24.06.2004 The crystalline lens

5. The primate visual systemHelmuth Radrich, 24.06.2004

6. The primate visual systemHelmuth Radrich, 24.06.2004 The fovea

7. The primate visual systemHelmuth Radrich, 24.06.2004 Rods and cones distribution

8. The primate visual systemHelmuth Radrich, 24.06.2004

9. The primate visual systemHelmuth Radrich, 24.06.2004 Information flow from eye to brain Via optic nerve Data is not “raw”… preprocessed by retina Human eye: –120 million rods –5 million cones –Another few millions of bipolar/amacrine/horizontal cells –Optic nerver: 1 million axons => A single ganglion cell axon receives information from many receptors in a region of the retina defining the cells receptive field

10. The primate visual systemHelmuth Radrich, 24.06.2004 The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

11. The primate visual systemHelmuth Radrich, 24.06.2004 Neural response types

12. The primate visual systemHelmuth Radrich, 24.06.2004 Receptive fields

13. The primate visual systemHelmuth Radrich, 24.06.2004 Parvo and magno cells

14. The primate visual systemHelmuth Radrich, 24.06.2004 Parvo and magno cells

15. The primate visual systemHelmuth Radrich, 24.06.2004 The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

16. The primate visual systemHelmuth Radrich, 24.06.2004 Intensity & perceived brightness

17. The primate visual systemHelmuth Radrich, 24.06.2004 Dark adaptation

18. The primate visual systemHelmuth Radrich, 24.06.2004 Relative sensitivity (wavelength)

19. The primate visual systemHelmuth Radrich, 24.06.2004 Visual angle

20. The primate visual systemHelmuth Radrich, 24.06.2004 Visual acuity

21. The primate visual systemHelmuth Radrich, 24.06.2004 The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis&spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

22. The primate visual systemHelmuth Radrich, 24.06.2004 Light distributions

23. The primate visual systemHelmuth Radrich, 24.06.2004 Approximation of square waves

24. The primate visual systemHelmuth Radrich, 24.06.2004

25. The primate visual systemHelmuth Radrich, 24.06.2004 Apparent brightness

26. The primate visual systemHelmuth Radrich, 24.06.2004 Modulation transfer function

27. The primate visual systemHelmuth Radrich, 24.06.2004 Frequency analysis (biological)

28. The primate visual systemHelmuth Radrich, 24.06.2004

29. The primate visual systemHelmuth Radrich, 24.06.2004 Spatial context (lat. inhibition)

30. The primate visual systemHelmuth Radrich, 24.06.2004

31. The primate visual systemHelmuth Radrich, 24.06.2004 Temporal context effects

32. The primate visual systemHelmuth Radrich, 24.06.2004 The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

33. The primate visual systemHelmuth Radrich, 24.06.2004 Properties of visual environment

34. The primate visual systemHelmuth Radrich, 24.06.2004 Masking

35. The primate visual systemHelmuth Radrich, 24.06.2004 Feature extraction

36. The primate visual systemHelmuth Radrich, 24.06.2004 Emergent features

37. The primate visual systemHelmuth Radrich, 24.06.2004 Figure and ground

38. The primate visual systemHelmuth Radrich, 24.06.2004

39. The primate visual systemHelmuth Radrich, 24.06.2004 Subjective contours

40. The primate visual systemHelmuth Radrich, 24.06.2004 Figural grouping

41. The primate visual systemHelmuth Radrich, 24.06.2004

42. The primate visual systemHelmuth Radrich, 24.06.2004 Texture defined grouping

43. The primate visual systemHelmuth Radrich, 24.06.2004 Spatial frequency grouping

44. The primate visual systemHelmuth Radrich, 24.06.2004 Good figures

45. The primate visual systemHelmuth Radrich, 24.06.2004 Good figures

46. The primate visual systemHelmuth Radrich, 24.06.2004 Good figures

47. The primate visual systemHelmuth Radrich, 24.06.2004 What is this???

48. The primate visual systemHelmuth Radrich, 24.06.2004 Conceptually driven processing

49. The primate visual systemHelmuth Radrich, 24.06.2004 Global vs. local processing

50. The primate visual systemHelmuth Radrich, 24.06.2004 Context and identification

51. The primate visual systemHelmuth Radrich, 24.06.2004

52. The primate visual systemHelmuth Radrich, 24.06.2004

53. The primate visual systemHelmuth Radrich, 24.06.2004 The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

54. The primate visual systemHelmuth Radrich, 24.06.2004

55. The primate visual systemHelmuth Radrich, 24.06.2004

56. The primate visual systemHelmuth Radrich, 24.06.2004

57. The primate visual systemHelmuth Radrich, 24.06.2004 Receptive fields (simple cortical)

58. The primate visual systemHelmuth Radrich, 24.06.2004

59. The primate visual systemHelmuth Radrich, 24.06.2004 Layer of V1

60. The primate visual systemHelmuth Radrich, 24.06.2004

61. The primate visual systemHelmuth Radrich, 24.06.2004 Visual pathways (human)

62. The primate visual systemHelmuth Radrich, 24.06.2004

63. The primate visual systemHelmuth Radrich, 24.06.2004 The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque monkey)

64. The primate visual systemHelmuth Radrich, 24.06.2004 Oram&Prett proposal Neurobiological data form macaque monkeys Analogies to human visual system  Object recognition as series of 4 computational stages in 7 major hierarchically arranged processing areas  Simple feed-forward network sufficient for computer simulation

65. The primate visual systemHelmuth Radrich, 24.06.2004

66. The primate visual systemHelmuth Radrich, 24.06.2004 like in humans two major processing streams (only form perception is discussed) strong similarities to human brain Interconnection not as complete as it could be Why????  Combinatorial explosion if object is to be recognized from simple features (only edges, etc.)  Basic edges etc. information not helpful in complex feature recognition at higher level

67. The primate visual systemHelmuth Radrich, 24.06.2004

68. The primate visual systemHelmuth Radrich, 24.06.2004

69. The primate visual systemHelmuth Radrich, 24.06.2004

70. The primate visual systemHelmuth Radrich, 24.06.2004 Min.-timings in information-stream Assumptions (biologically plausible): about 5 ms to trigger firing in the next neuron + some ms for signal transmission inside neurons (minimum) With the experimentally measured timings for the arrival of the first reactions in STPa after stimulus presentation (above):  Only 7 interneuron connections can lay on the way of the signal (correspond to biological layers of the visual cortex)  No time for lateral inhibition or feedback processes to interact with the information processing  Feed-forward only model is plausible, but only half of the story in higher perception

71. The primate visual systemHelmuth Radrich, 24.06.2004

72. The primate visual systemHelmuth Radrich, 24.06.2004 Reference Coren, S., Ward, L. M. and Enns, J. T. (1993). Sensation and perception Oram M. W. and Prrett, D. I. (1994), Modeling visual cognition from neurobiological constraints. Neural Networks 7 (6/7), 945-972

73. The primate visual systemHelmuth Radrich, 24.06.2004 The END Thank you for your attention!