Cognitive Neuroscience

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Author:
jstagl
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69347
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Cognitive Neuroscience
Updated:
2011-02-27 20:43:43
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Perception
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Exam #2
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  1. Why isn't perception a faithful representation
    Perceptions are constructions by our CNS that are influenced by the nervous systems ability to learn and its dynamic integration, modulations, and flexible controls of stimuli
  2. Perception is heavily influenced by
    top down processes
  3. Transduction
    Transference of stimulus energy to neural firing
  4. transduction is accomplished by _____which are specialized according to ________
    • sensory receptors
    • mechanical, chemical, and thermal
  5. the source of sensory receptors are (4):
    exteroreceptors (stimuli on body: skin, tongue) telereceptors (distant stim.: vision, audition, smell) - proprioceptors (muscles, joints, vestibular system) - interoceptors (internal organs)
  6. Sensory coding by 4 properties
    • Modality (types of receptors)
    • Position (location of receptors and pattern of firing)
    • Intensity (# of neurons and frequency)
    • Timing (Onset)
  7. Principles of Perception
    • 1. Sensory receptors optimized to detect different stimuli
    • 2. Sensory info is carried along labeled lines
    • 3. center-surround organization
    • 4. decussation of sensory fibers
    • 5.topographic representation, but distorted
  8. different types of inputs
    • optimized to detect different stimuli:
    • touch
    • taste
    • smell
    • hear
    • see
  9. Sensory info is carried along labeled lines
    • sensory info is categorized
    • tactile info is perceived as its cannels through different parts of our brains
  10. center surround organization of the receptive field
    • the way the perceptual field is organized
    • the center needs to be stimulated for an excitatory effect
    • peripheral surround portion has an inhibitory effect
    • activity of a cell depends on what part is stimulating
  11. cell is at a
    baseline activity so taht you can easily modulate activity.
  12. if you stimulate the surround
    you go below baseline
  13. if you stimulate the center
    its excitatory and you go above baseline
  14. if you activate both the surround and the center
    you get a summed total effect
  15. the purpose of center surround is to
    make perception more accurate- yes it comes from here and no it didnt come from here
  16. decussation of sensory fibers
    left side is represented in the right and vice versa
  17. Topographic representation/but distorted
    • A. Visual system: over representation of fovea
    • B. Somatosensory system: over-representation of thumb, mouth, tongue
  18. Visual system
    • Visual assocation cortex
    • brain is building our visual perception
    • distance is something you get from visual (auditory too)
  19. Sensory sytems
    • 1.Visual
    • 2.Auditory
    • 3.Olfactory
    • 4.Somatosensory
    • 5.Gustatory
  20. Human visual system
    • 1.50% of human brain is dedicated to vision
    • 2. outgrowth of the brain
    • 3. neural tube in ontogeny
  21. parts of the eye
    • lens
    • iris
    • pupil
    • anterior chamber
    • cornea
    • retina
    • fovea
    • blind spot
    • optic nerve
    • choroid
  22. Cones
    respond to light of different colors, found more in fovea
  23. Rods
    • sensitive to brightness, not colors
    • found in periphery of retina
    • important at night
  24. shooting stars at nigth
    rods
  25. Process of Neural Transduction
    • 1. After converting light into electrical signalsin their cell membranes, rods and cones transmit this information to other neurons in internal circuits in the retina for processing.
    • 2. From these cells, messages go to the final retinal station, the ganglion cells, whose axons exit the eyeball at the optic disc and form the optic nerve, which contains about one million axons.
    • 3. Because all the nerve fibers converge at the optic disc, no rods or cones are in this area and it forms a "blind spot"on the retina: this may be easily demonstrated
  26. choroid is the
    thick blood cells
  27. retina is the
    whole back lining
  28. fovea is the
    subset of the retina that corresponds to the cetnral part of the visual field
  29. optic nerve is hte
    nerves that come together and leave the visual field
  30. blind spot
    the part of the visual scene that no longer has visual representation beceause there are no photoreceptors there due to the departure of the optic nerve
  31. nastagmis
    the eyes are constantly moving so we never actually see our blind spot
  32. more cones in the
    fovea
  33. more rods in teh
    periphery
  34. optic chiasm
    where the decussation occurs and nerve fibers cross over
  35. optic tract
    leads from the chiasm to the thalams (relay station)
  36. nuclei of the thalamus is the
    Lateral Geniculate Nucleus (LGN)
  37. visual path
    • optic nerve
    • optic chiasm
    • optic tracts
    • thalamus
    • LGN
    • optic radiations
    • higher visual areas
    • primary visual cortex
  38. left visual field corresponds with
    right visual field corresponds with
    • right temporal retina
    • left nasal retina

    • left temporal retina
    • right nasal retina
  39. hemifield closest to the fovea is the
    right or left medial hemi fields
  40. hemi-field closest to the peripheral portion
    lateral right and left hemi fields
  41. temporal hemi retina represents
    contralateral hemifields medial portion
  42. nasal hemi retina represents
    ipsilateral fields lateral portion
  43. the relay station for hte perceputal system is
    thalamus (LGN)
  44. which hemi retina crosses over and where
    the nasal hemi retina at the optic chiasm
  45. Vision is generated by photoreceptors in the ____, a layer of cells at the back of the eye.
    retina,
  46. The information leaves the eye by way of the ___, and there is a partial crossing of axons at the ____.
    • optic nerve
    • optic chiasm.
  47. After, the axons are called the __D__. The __D_ then lead to the __E_, where all the axons must synapse.
    • optic tract
    • lateral geniculate nucleus,
  48. From there, the __E__axons fan out through the deep white matter of the brain as the __F__, which will ultimately travel to __G__, at the back of the brain.
    • LGN axons
    • optic radiations
    • primary visual cortex
  49. what type of organization in V1
    Columnar
  50. Within a cortical module:
    set of orientation columns, ocular dominance columns, and blobs … all with similar receptive fieldsWithin
  51. study what each eye sees if there is a lesion at a certain spot! reminder!
  52. Receptive Field
    area of the retina that when stimulated with light, changes the cells membrane potential
  53. Retinotopic map
    neighboring cells in the retina feed information to neighboring places in their target structures

    capture everything in visual scene and corresponds with different visual area
  54. LGN has what type of arrangement
    annual and center surround arrangement for receptive field
  55. Receptive Field tells
    : What partof the visual field does a neuron respond to?
  56. Selectivity tells
    what kind of visual information a neuron responds to
  57. V1 has edge detectors
    cars taht are representations of the receptive field
  58. Parallel processing
    Different kinds of visual information are processed in parallel by different neural populations
  59. What makes a visual region?
    • Cytoarchitecture
    • Intracortical connections
    • Retinotopy
    • Functional properties
  60. Retino-collicular pathway
    • • “rough and ready” vision
    • • responsible for “blindsight”when main pathway is damaged
  61. visual cortex to parietal lobe
    where/how
  62. visual cortex to temporal lobe
  63. what
  64. M1
    part that allows us to detect motion in the visual system
  65. Olfaction and Gustation
    Pleasant tastes and odors of food, drink, andflowers; noxious odors of decay and danger(predators); bitter tastes of toxic substances

    Chemical senses very old, perhaps the first typeof sense to evolve in cells (chemotaxis occurs inbacteria and single cells)
  66. if we want to know where to present stimuli and what is the selectivity process
    we present bars of light in different orientations and find the preferred orientation
  67. if there is no light in the receptive field in a certain location
    tehre is no stimulus so baseline firing
  68. 1st landing spot is
    V1
  69. V1 is sensitive to
    bars of light of different orientations
  70. V4
    contains cells that fire maximally for differnt types of colors
  71. serial-parallel processing
    different regions care about differnt features(color contour, motion)
  72. Olfaction
    • humans are microsomatic
    • sense of smell relatively poor compared to other animals
  73. main olfaction component
    glomeruli (similar to retina)
  74. glomeruli...
    clump together and axons leaving create the olfactory buls
  75. olfaction is different because
    does not have a relay to the thalamus
  76. olfactory cortices
    • primary olfactory cortex
    • orbitofrontal cortex (secondary olfactory area)
  77. odorant with high rate of absorption plus high air flow entering nostril equals
    large neuronal response
  78. odorant with low rate of absorpotion plus low flow of air
    equals large neuronal response
  79. smells are coded by
    don't know yet but elicit spatiotemporal patterns of activation in the olfactory bulb
  80. anosmia
    loss of sense of smell
  81. olfactory hallucinations can be
    result of temporal lobe seizures
  82. odorants and tastes are part of
    chemical stimulations
  83. tastes
    • sour
    • salty
    • bitter
    • sweet
    • umami
  84. how are different tastes coded?
    • little is known, taste nuerons broadly attuned to taste qualities
    • no distint topographic map
  85. gustatory properties
    • taste bud
    • taste nueron/nerve
    • tongue
  86. Audition
    • transduction stimulti connect to neuronal response input (vibrations sound waves),
    • this stimulates the timpanic membrane
    • moves the fluid that moves the hair cells in cochlea to ove
    • neural transductions happens in the hair cells
    • axons leave through auditory nerves
  87. pathway audition
    • auditory nerve
    • cochlear nuclei
    • superior oliveri nucleus
    • auditory cortex
    • medial geniculate nucleus
    • inferior colliculus
  88. auditory pathways summarized
    • Auditory pathway:–primary receptors (hair cells)
    • •inner ear (in the cochlea: the organ of Corti)–intermediate-level relays
    • •medial geniculate nucleus of thalamus
    • •inferior colliculus in the brainstem–primary cortical representation
    • •auditory cortex in temporal lobe–higher integrative areas
  89. sound characteristics
    frequency and amplitude
  90. organization of auditory cortex
    tonotopic

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