1. Visual Signal Processing: 2
“Intuition tells us that the brain is complicated. We do
complicated things, in immense variety. We breathe, cough,
sneeze, vomit, mate, swallow, and urinate; we add and
subtract, speak, and even argue, write, sing, and compose
quartets, poems, novels, and plays; we play baseball and
musical instruments. We perceive and think. How could the
organ responsible for doing all that not be complex?”
Eye Brain and Vision : David Hubel

2. Visual Information Processing:

3. Touch : Mono frequency system
1. Modality
2. Location
3. Timing
4. Intensity

4. Hearing: Multi-frequency system

5. Bheraghat Jabalpur MP

6. Visual Signal Processing
1. Modality - EM
2. Location Form, shape, depth
3. Timing - Motion
4. Intensity -

7. Retina

8. Rods and Cones
Cones Rods
Light Low High
Pigment Less More
Response Fast Slow
Use Day
Loss Blindness Night Blindness
Acuity High Low
Saturation Intense light Day light
Color Yes No
Fovea All Absent
Population Low High

9. Phototransduction
Dark
Light

10. Receptive Field

11. Receptive field

12. Receptive field: Lateral Inhibition

13. Receptive Field: Ganglion Cells
Stimulus M Cells P Cells
Color No Yes
Contrast High Low
Spatial Low High
Temporal High Low

14. Ganglion Cell : Contrast discrimination

16. Lateral Geniculate Nucleus

17. Lateral Geniculate Ganglia

19. Organization of Visual Cortex

21. Visual Cortex Architecture

22. Visual Cortex Architecture

23. Recording from Visual Cortex

25. Simple Cell

26. Complex Cells

27. Complex Cell

28. Complex Cells

29. Hypercomplex Cells

30. Significance of Movement Cells

31. Orientation Column

33. Orientation column of visual cortex

34. Illusion of Edges: V2 in Monkey

35. Inferior Temporal neuron response to Form

37. Face and Complex Form Recognition ITC

39. 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

40. Ocular dominance column

42. Visual Cortex Architecture

43. Motion in the visual field

45. PET scan of MT area for Motion Processing

46. Depth of vision

47. Neuronal basis of stereoscopic vision

48. 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.)