1. © Cengage Learning 2016 Chapter 5 Vision

2. © Cengage Learning 2016 Sensation and Perception Sensation –Ability to detect and encode information –Raw data –Each sense has specialized receptors sensitive to a particular kind of energy Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

3. © Cengage Learning 2016 Sensation and Perception Perception –Ability to organize and interpret information –Subjective experience of raw data –Law of specific nerve energies activity by a particular nerve always conveys the same type of information to the brain –Perception not always reality

4. © Cengage Learning 2016 Perceptual Illusions Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

5. © Cengage Learning 2016 Perceptual Illusions Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

6. © Cengage Learning 2016 Perceptual Illusions Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

7. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 Vision Vision is our primary sensory experience More of the human brain is dedicated to vision than to any other sense

8. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 Structure of the Eye Cornea –Clear outer covering Iris –Opens and closes to allow more or less light in –The hole in the iris is called the pupil. Lens –Focuses light –Bends to accommodate near and far objects Retina –Where light energy initiates neural activity

9. © Cengage Learning 2016 Cross Section of a Vertebrate Eye

10. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 The Basics: Visible Light and the Structure of the Eye Myopia (nearsightedness) –Inability to bring distant objects into clear focus –Focal point of light falls short of the retina Hyperopia (farsightedness) –Inability to focus on near objects –Focal point of light falls beyond the retina Presbyopia –Common form of hyperopia seen in older adults

11. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

12. © Cengage Learning 2016 The Vertebrate Retina

13. © Cengage Learning 2016 Bipolar Cells Get info from visual receptors at the back of the eye send messages to ganglion cells

14. © Cengage Learning 2016 Amacrine Cells Get info from bipolar cells Control the ability of the ganglion cells to respond to specific aspects of visual stimuli

15. © Cengage Learning 2016 The Optic Nerve Consists of the axons of ganglion cells exits through the back of the eye and travel to the brain Blind spot (optic disc) –Region of the retina where there are no photoreceptors –Activity: Find Your Blind Spot!

16. © Cengage Learning 2016 Visual Path Within the Eye

17. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 Retina of the Retina Retina –Light-sensitive surface at the back of the eye –consists of neurons and photoreceptor cells Convert light to action potentials Discriminate wavelengths so we see colors –Which is an example of a sensation? Perception? –Images on retina is upside down and backward Brain makes the adjustment

18. © Cengage Learning 2016 Our Amazing Brain For emaxlpe, it deson’t mttaer in waht oredr the ltteers in a wrod aepapr, the olny iprmoatnt tihng is taht the frist and lsat ltteer are in the rghit pcale. The rset can be a toatl mses and you can sitll raed it wouthit pobelrm. S1M1L4RLY, Y0UR M1ND 15 R34D1NG 7H15 4U70M471C4LLY W17H0U7 3V3N 7H1NK1NG 4B0U7 17. Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

19. © Cengage Learning 2016 Structure of the Eye Fovea –“pit” –Region at the center of the retina –Receptors densely packed Lots of cones –Each one has direct line to brain –Allows us to register exact location of input Clearest vision –Needed for detail Reading, driving Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

20. © Cengage Learning 2016 Central Focus Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

21. © Cengage Learning 2016 Structure of the Eye Periphery of the retina –Less detailed vision –Doesn’t need as much light as fovea –Fovea = visual acuity –Periphery = see in dim light

22. © Cengage Learning 2016 Acuity Across the Visual Field Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

23. © Cengage Learning 2016 Convergence of Input onto Bipolar Cells

24. © Cengage Learning 2016 The Arrangement of Visual Receptors Highly adaptive –How Animals See the World (3 min.)How Animals See the World (3 min.)

25. © Cengage Learning 2016 Rods and Cones

26. © Cengage Learning 2016 Rods and Cones Retina has two kinds of receptors –Rods: periphery of the eye 120 million per retina Sensitive to low levels of light night vision Each ganglion cell excited by many rods

27. © Cengage Learning 2016 –Cones fovea only 6 million per retina responsive to bright light color vision and high visual acuity Each ganglion cell excited by a single cone Rods and Cones

28. © Cengage Learning 2016 Rods and Cones Rods and cones converge onto 1 million axons in the optic nerve The ratio of rods to cones is higher in species that are more active at dim light Individual differences –Athletes and aim

29. © Cengage Learning 2016 Color Vision Visible light is a portion of the electromagnetic spectrum The perception of color is dependent upon the wavelength of the light “Visible” wavelengths are dependent upon the species’ receptors Humans perceive wavelengths between 400 and 700 nanometers (nm)

30. © Cengage Learning 2016 Visible Light on the Electromagnetic Spectrum

31. © Cengage Learning 2016 Color Vision Why do we see in color? –Evolutionary advantage Detect ripe fruit How do we see color? –Light waves stimulate cones –Red, green, blue Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

32. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 Color Vision Three Types of Cone Pigments –Most responsive to: 419 nm (“blue” or short wavelength) 531 nm (“green” or middle wavelength) 559 nm (“red” or long wavelength) –There are about equal numbers of red and green cones, but fewer blue cones.

33. © Cengage Learning 2016 Distribution of Cones in Two Human Retinas

34. © Cengage Learning 2016 Color Vision Trichromatic Theory (1800’s) –Color vision based on three primary colors: red, green, and blue “RGB let’s us see!” –Color is determined by the responses of the different cone types –Each cone responds to some wavelengths more than others –The ratio of activity across the three types of cones determines the color

35. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

36. © Cengage Learning 2016 Color Vision Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

37. © Cengage Learning 2016 Color Vision Trichromatic Theory –Can explain different types of color blindness Examples of color-deficient vision 1 in 20 males, 1 in 400 females –Genes for pigments on X chromosome –Limitation: Four basic colors: red, green, yellow, and blue Cannot explain afterimages –Red-green; blue-yellow Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

38. © Cengage Learning 2016 Demonstrating Afterimages Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

39. © Cengage Learning 2016 Demonstrating Afterimages Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

40. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 Color Vision Opponent-Process Theory –Ewald Hering –Perceive colors in terms of opposites Red versus green, blue versus yellow, black vs. white –Opponent processing occurs in bipolar cells Cells excited by one set of wavelengths and inhibited by another –Ex: some neurons are “turned on” by red and “turned off” by “green”

41. © Cengage Learning 2016 Limitations of Color Vision Theories Both theories have limitations –Can’t explain color constancy ability to recognize color stays same despite changes in lighting Retinex theory –Cortex compares info from different parts of retina to determine brightness, color

42. © Cengage Learning 2016 The Dress

43. © Cengage Learning 2016 Why do people see different colors? Two explanations, one paragraph each, of why people see different colors. One paragraph discussing explanation is most convincing to you and why. Please cite sources. 15 points possible The Dress

44. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 [Insert Fig. 9-10]

45. © Cengage Learning 2016 Processing of Visual Information Lateral geniculate nucleus (LGN) –Part of the thalamus –Specialized for visual perception –Destination for most ganglion cell axons –Sends axons to other parts of the thalamus and to the visual areas of the occipital cortex The cortex and thalamus constantly feed information back and forth to each other

46. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 Further Processing Retinal Ganglion Cells (RGC) - Magnocellular cell (M-cell) Magno = large Receives input from rods Sensitive to light, pattern and moving stimuli –Parvocellular cell (P-cell) Parvo = small Receives input from cones Sensitive to color, fine details

47. © Cengage Learning 2016 The Primary Visual Cortex Primary visual cortex (area V1) –receives information from the LGN –first stage of visual processing Damage to V1 –blindsight

48. © Cengage Learning 2016 5.3 Parallel Processing in the Visual Cortex At least 80 brain areas that contribute to vision in different ways. –Shape, color, movement, location

49. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 Dorsal and Ventral Visual Paths Dorsal Visual Stream –Pathway from occipital lobe to the parietal lobe –The “how” pathway Responds to image movement Tell us how to act toward objects –Ex: reaching to catch a ball

50. © Cengage Learning 2016 Dorsal and Ventral Visual Streams Ventral Visual Stream –Pathway from occipital lobe to the temporal lobe –The “what” pathway Recognition and identification –Ex: faces Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

51. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

52. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 Agnosia = not knowing Visual-Form Agnosia –Inability to recognize objects or drawings of objects despite having vision –Video clip (5:00 minutes)Video clip –Cannot recognize objects, but can: Copy objects and draw objects from memory Correctly shape hands when grasping for objects, despite not recognizing those objects Injury to the “What” Pathway

53. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

54. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

55. © Cengage Learning 2016 Injury to the “What” Pathway Color Agnosia (achromatopsia) –Inability to recognize colors Face Agnosia (prosopagnosia) –Inability to recognize faces –Damage to fusiform gyrus –60 Minutes segment (12:00 minutes)60 Minutes segment Capras delusion –Secrets of the Mind (start at 7:30) Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

56. © Cengage Learning 2016 Face Recognition – The Fusiform Gyrus

57. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9 Injury to the Pathway Leading to the Cortex Monocular Blindness –Destruction of the retina or optic nerve of one eye –produces loss of sight in that eye Homonymous Hemianopia –Blindness of an entire left or right visual field –Damage to LGN, optic tract or visual cortex –Related to visual neglect (start at 3:30)Related to visual neglect

58. © Cengage Learning 2016 Injury to the Pathway Leading to the Cortex Quadrantanopia –Blindness of one quadrant of the visual field Scotoma –Small blind spot in the visual field –Caused by a small lesion in visual cortex –Eyes are always moving, brain fills in gap Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9

59. © Cengage Learning 2016 Kolb & Whishaw, An Introduction to Brain and Behavior, Fourth Edition - Chapter 9