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PSY-2 Ch07 Vision
- 1. Ch07: Vision ➔Visual Transduction ➔VisualProcessing in the CNS ➔Receptive Fields for Vision ➔Color Vision
- 2. CASE STUDY: PATIENTD.F. Seeing without perceiving.
- 3. CASE STUDY: PATIENTD.F. Seeing without perceiving.
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- 5. Figure 7.1 Structuresof the Human • CORNEA • PUPIL • IRIS • LENS • CILIARY MUSCLE • RETINA • OPTIC NERVE VISUAL TRANSDUCTION
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- 8. Figure 7.2 FocusingImages on the Retina • ACCOMMODATION: using ciliary muscles to change lens shape • MYOPIA: nearsightedness • HYPEROPIA: farsightedness • PRESBYOPIA: age-related farsightedness VISUAL TRANSDUCTION
- 9. Figure 7.3 Anatomyof the Retina (Part 1) Cells in the Retina – PHOTORECEPTORS: sensory neurons that detect light – BIPOLAR CELLS: connect photoreceptors and ganglion cells – GANGLION CELLS: axons form the optic nerve VISUAL TRANSDUCTION
- 10. Figure 7.3 Anatomyof the Retina (Part 1) Cells in the Retina – HORIZONTAL CELLS: link receptor cells and bipolar cells – AMACRINE CELLS: link bipolar cells and ganglion cells VISUAL TRANSDUCTION
- 11. Figure 7.3 Anatomyof the Retina (Part 1) • Only ganglion cells generate action potentials • CONVERGENCE: info from many photoreceptors converges onto each ganglion cell VISUAL TRANSDUCTION
- 12. 12 SCOTOPIC SYSTEM (RODS): •100million per eye •Low light •Rhodopsin •Insensitive to color •Low visual acuity •Peripheral VISUAL TRANSDUCTION
- 13. 13 PHOTOPIC SYSTEM (CONES): •4million per eye •Bright light •Opsin (3 Types) •Detect color •High visual acuity •Central VISUAL TRANSDUCTION
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- 15. Figure 7.4 Hyperpolarizationof Photoreceptors VISUAL TRANSDUCTION
- 16. • OPTIC DISC:where blood vessels and ganglion cell axons leave the eye • BLIND SPOT: due to lack of photoreceptors in the optic disc • FOVEA: center of retina; high density of smaller, tightly- packed cones VISUAL TRANSDUCTION
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- 21. Ch07: Vision ➔Visual Transduction ➔VisualProcessing in the CNS ➔Receptive Fields for Vision ➔Color Vision
- 22. Visual Processing inthe Brain • LATERAL GENICULATE NUCLEUS (LGN): the visual part of the thalamus • OPTIC RADIATIONS: axons of LGN neurons that terminate in the occipital cortex CNS VISUAL PROCESSING
- 23. Visual Processing inthe Brain • PRIMARY VISUAL CORTEX (V1): region of occipital cortex where most visual information first arrives • EXTRASTRIATE CORTEX: visual cortex outside of V1 CNS VISUAL PROCESSING
- 24. CNS VISUAL PROCESSING OpticNerve Optic Chiasm Lateral Geniculate Nucleus Superior Colliculus Striate Cortex (V1) Optic Radiations Retina
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- 27. TOPOGRAPHIC PROJECTION: organization that preserves thepoint- to-point map between neighboring parts of space CNS VISUAL PROCESSING
- 28. • SCOTOMA: perceptualgap, due to injury • BLINDSIGHT: inability to consciously perceive visual cues, yet able to make visual discrimination CNS VISUAL PROCESSING
- 29. • Where doesinformation go after it leaves V1? CNS VISUAL PROCESSING
- 30. Animation 7.3 Click hereto watch an animation of the visual pathways in the brain.
- 31. Video 7.1 Click hereto watch a video about object recognition.
- 32. Ch07: Vision ➔Visual Transduction ➔VisualProcessing in the CNS ➔Receptive Fields for Vision ➔Color Vision
- 33. RECEPTIVE FIELDS FORVISION At rest, in darkness, photoreceptors release GLU
- 34. RECEPTIVE FIELDS FORVISION GLU depolarizes some bipolar cells and hyperpolarizes others • ON-CENTER BIPOLAR CELLS: turning on light excites the cell • OFF-CENTER BIPOLAR CELLS: turning off light in the center of the field excites the cells
- 35. Bipolar cells alsorelease GLU, which always depolarizes ganglion cells RECEPTIVE FIELDS FOR VISION
- 36. Types of GanglionCells • On-center bipolar cells excite ON-CENTER GANGLION CELLS, when light is turned on • Off-center bipolar cells excite OFF-CENTER GANGLION CELLS, when light is turned off RECEPTIVE FIELDS FOR VISION
- 37. RECEPTIVE FIELD: thestimulus region and features that affect the activity of a cell in a sensory system –On-center/off-surround –Off-center/on-surround RECEPTIVE FIELDS FOR VISION
- 38. Figure 7.13 ReceptiveFields of Retinal Cells (Part 1) RECEPTIVE FIELDS FOR VISION
- 39. Animation 7.4 Click hereto watch a video overview of receptive fields for vision.
- 40. LATERAL INHIBITION: sensoryreceptor cells inhibit information from neighboring receptor cells RECEPTIVE FIELDS FOR VISION
- 41. RECEPTIVE FIELDS FORVISION
- 42. Neurons in thevisual cortex have varied receptor fields: • SIMPLE CORTICAL CELLS: also called bar or edge detectors—respond to an edge or bar of a particular width, orientation, and location • COMPLEX CORTICAL CELLS: also respond to a bar of a particular width and orientation, but may be located anywhere in the visual field RECEPTIVE FIELDS FOR VISION
- 43. RECEPTIVE FIELDS FORVISION
- 44. RECEPTIVE FIELDS FORVISION
- 45. RECEPTIVE FIELDS FORVISION
- 46. RECEPTIVE FIELDS FORVISION
- 47. RECEPTIVE FIELDS FORVISION
- 48. RECEPTIVE FIELDS FORVISION
- 49. Ch07: Vision ➔Visual Transduction ➔VisualProcessing in the CNS ➔Receptive Fields for Vision ➔Color Vision
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- 51. COLOR VISION Dimensions ofcolor perception: 1. Brightness–varies from dark to light 2. Hue–varies throughout all colors 3. Saturation–varies from full colors to gray at the center
- 52. COLOR VISION Cones containone of three pigments, called opsins, with overlapping but different peaks of sensitivity.
- 53. In the secondstage of color processing: – Most ganglion cells and LGN cells fire in response to some wavelengths and are inhibited by others – COLOR OPPONENT CELL: has opposite firing responses to different regions of the spectrum – EX: a plus L/minus M (+L/–M) cell is stimulated above 600 nm and inhibited at shorter wavelengths COLOR VISION
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