PSY 241 Lecture 10

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PSY 241 Lecture 10
2013-03-12 21:44:17
psychobiology zavala

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  1. Iris
    controls amount of light that enters through the pupil (opening of the iris)
  2. Retina
    Contains the photoreceptors that convert light to a neural impulse (contains 6 different types of cells)
  3. Lens
    Structure that focuses light onto the back of retina
  4. Ciliary muscle
    controls the shape of the lens
  5. Optic nerve
    bundle of axons that leave eye
  6. Optic disk
    portion of the retina that does not contain photoreceptors
  7. fovea
    sharp vision
  8. Accomodation
    change in the shape of the lens b the ciliary muscles to maintain focus of an image onto the back of the retina and maintain sharp vision
  9. Eye movement is controlled by 3 pairs of _____________.
    extraocular muscles
  10. Nearsighted Vision
    Lens does not project the image perfectly onto back of the eye, so you experience blurry vision
  11. Light can be thought of as:
    • Particles of energy (photons)
    • Waves of electromagnetic radiation
  12. Waves of electromagnetic radiation
    • Amplitude/Intensity = brightness
    • Wavelength = hue (frequency of oscillation)/color
    • Purity (one wavelength)
  13. Two types of retina
    Rods and cones
  14. Bipolar cells
    receive input from photoreceptors and synapse on ganglion cells whose axons form the optic nerve, which carries information to the brain
  15. Horizontal cells in the retina
    contact photoreceptors and bipolar cells
  16. amacrine cells
    contact bipolar and ganglion cells
  17. Fovea is made of many rods or cones?
  18. Scotopic system (rods)
    works in dim light (high sensitivity) but is insensitive to color (colorless)
  19. Convergence
    information from many rods converges onto each ganglion cell
  20. Photopic system (cones)
    requires more light and allows color vision
  21. Amacrine and Horizontalcells help to....
    spread activity to nearby cells bipolar and ganglion cells
  22. Rods are normally active when ....
    no light is present and are constantly inhibiting the bipolar cells
  23. Bipolar cells release an
    excitatory neurotransmitter
  24. rods release an __________
    inhibitatory neurotransmitter
  25. Photoreceptors in the dark continually release neurotransmitter - light triggers a _____________ of the cell, so it releases ______ neurotransmitter
    hyperpolarization; less
  26. The ______ of the hyperpolarizing signal determines how much neurotransmitter is released
  27. Lamella
    a layer of membrane containing photopigments; found in the rods and cones
  28. Photopigment
    Responsible for the transduction of visual information, and contains "opsin" (protein) and "retinal" (lipid)
  29. Opsin
    a protein found in rods and cones (each have a different type) that is responsive to different wavelengths of light
  30. Retinal
    a chemical synthesized from vitamin A
  31. Rodopsin
    type of photopigment found in rods
  32. What happens to bipolar and ganglion cells?
    becomes active
  33. Trichromatic Theory
    • 3 kinds of photoreceptors (3 cones)
    • each cone max sensitive to short, medium, or long wavelengths
    • determines by 3 opsin within each photoreceptor
    • color perceived through relative rates of response of each cone
    • any response by any coneis ambiguous (CNS processes relative activity across all cones)
  34. Color blindness
    • lack of functional cones
    • rare
    • see objects through stimulation of rods
    • perceive gray
    • poor visual acuity
  35. Protanopia/deuteranopia
    • red/green color deficiency
    • shades of yellow/brown
    • normal visual acuity
    • red cone filled with green opsin/green cone filled with red opsin
    • inherited transmission
    • linked to x chromosome
  36. myopia
    lens does not project directly on retina
  37. cataract
    clouding that develops in the lens and light is obstructed
  38. glaucoma
    loss of retinal ganglion cells (optic nerve is damaged)
  39. macular degeneration
    loss of cells with in the center of the visual field
  40. blind spot
    result of axons exiting retina
  41. saccadic eye movements
    rapid jerky involuntary eye movements for accurate scanning of a visual scene
  42. 3 steps required for perception of visual images
    • Detection
    • Transduction
    • Coding
  43. Detection
    absorption of physical energy by receptors
  44. transduction
    conversion of physical energy to an electrochemical signal that neurons can recognize (an action potential)
  45. coding
    signals are analyzed and we execute a response
  46. Retino-Geniculo-Cortical Pathway
    • Retina
    • Optic Nerve
    • Optic Ciasm
    • Optic Tract
    • Lateral Geniculate Nucleus (Thalamus) - 80-90% of retinal cells
    • -superior colliculus - 10-20%
    • Optic Radiations - Axon from thalamic neuron
    • Primary Visual Cortex (V1 Cortex or Striate Cortex)