Neuroscience unit 2

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Neuroscience unit 2
2010-03-03 04:15:46

neuroscience flashcards unit 2
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  1. the primary _____ cortex is organized tonitopically
  2. the inferior colliculi and medial geniculate nuclei are components of the ______ system
  3. what seperates the left and right cerebral hemispheres?
    the cerebral commissures
  4. what is the most highly lateralized of all cognitive abilities?
  5. aphasia
    brain damage produced defecit in the ability to produce or comprehend language - left hemisphere damage/Broca's area
  6. where is Broca's area?
    inferior prefrontal cortex
  7. apraxia
    associated with left hemisphere damage, but the symptoms are bilateral. difficulty performing movements when asked to perform them out of context
  8. left hemisphere functions
    language, voluntary movement
  9. what were the results of the cat experiments by Myers and Sperry?
    the function of the corpus callossum is to transfer learned information between hemispheres. when it is cut, each hemisphere can function independently. one hemisphere working alone can learn simple tasks as rapidly as two. transferring the eye patch, however, tested the other hemisphere and performance immediately dropped
  10. cross cuing
    the means by which the two hemispheres communicate through indirect pathways through the brain stem/external route
  11. lateralization of function: VISION
    • left: words, letters
    • right: faces, geometric patterns, emotional expression
  12. lateralization of function: AUDITORY
    • left: language sounds
    • right: nonlanguage sounds, music
  13. left hemisphere interpreter
    a cognitive approach/hypothetical neuronal mechanism that asseses patterns of events and tries to make sense of them
  14. what do free nerve endings detect?
    temperature and pain
  15. outer ear (three parts)
    pinna, ear canal, tympanic membrane
  16. what is the difference between the dorsal column-medial lemniscus system and the anterolateral system?
    • DCMLS: touch and proprioception
    • Anterolateral system: temperature and pain
  17. What is the difference b/w pacinian corpuscles, ruffini corpuscles, and merkel's disks
    • pacinian corpuscles: rapid response, deeper pressure
    • Ruffini corpuscles: slower response, shallow pressure
    • Merkel's disks slower response, stretching
  18. Cortex of the left inferior prefrontal lobe is known as
    Broca's area
  19. damage to the ____ hemisphere is more likely to produce ipsilateral motor problems
  20. musical ability, spatial ability,and _____ are viewed as right-hemisphere specialization
  21. three common theories of cerebral lateralization are analytic synthetic theory, the motor theory, and the ____ theory
  22. alexia v. agraphia
    • alexia: inability to read
    • agraphia: inability to write
  23. what is the role of the left angular gyrus in language?
    posterior to wernicke's area, comprehending language related visual input
  24. conduction aphasia
    damage to the pathway connection Broca's and Wernicke's area (arcuate fascilculus). difficulty repeating words that had just been heard, although comprehension and spontaneous speech would be intact
  25. the ____ gyrus translates the visual form of a read word into an auditory code
  26. the ____ cortex controls the muscles of articulation
    primary motor
  27. the ____ cortex perceives the written word
    primary visual
  28. the ____ gyrus translates the visual form of a read word into an auditory code
  29. the _____ cortex perceives the spoken word
    primary auditory
  30. unilateral neglect syndrome
    • lack of attention to the left half of things
    • neglect usually dissipates over a few months
    • right parietal lobe damage
  31. opponent process theory
    complementary afterimages
  32. retinex
  33. blobs
    cytochrome oxidase
  34. ocular dominance columns
    striate cortex
  35. the axons of retinal ganglion cells leave the eyeball at the
    blind spot
  36. the area of the retina tha tmediates high acuity vision is the
  37. cones are the receptors of the ____ system, which functions only in good lighting
  38. the retinal ganglion cells from the nasal hemiretinas decussate via the
    optic chiasm
  39. the photopigment of rods is
  40. the high degree of _____ characteristic of the scotopic system increases its sensitivity but decreases its acuity
  41. areas of the cortex that receive input from more than one sensory system are called
  42. the three principles of sensory system organization
    • 1. hierarchical organization
    • 2. functional segregation
    • 3. parallel processing
  43. the middle ______ is is the incus
  44. the auditory nerve is a branch of cranial nerve VIII via the _____ nerve
    auditory vestibular
  45. the axons of the auditory nerves synapse n the ipsilateral ____ nuclei
  46. one function of the superior olives is sound _____
  47. many studies of visual auditory interactions have focused on association cortex in the ________
    posterior parietal lobe
  48. the inferior colliculi and medial geniculate nuclei are components of the ______ system
  49. the dorsal column medial lemniscus system and anterolateral system are pathways of the _________
    somatosensory system
  50. the ventral posterior nuclei, the intralaminar nuclei, and the parafasicular nuclei are thalamic nuclei of the ____ system
  51. one pathway of the ____ system projects from the amygdala and piriform cortex to the orbitofrontal cortex
  52. unlike the neuronal projections of all other sensory systems those of the ________ are primarily ipsilateral
  53. rods versus cones
    rods: 120 million/abundant in PERIPHERAL retina/best for low light conditions/detect brightness and movement/low acuity

    cones: 6 million/abundant in fovea/best for bright light conditions/detect color/high acuity
  54. magnocelluar / parvocellular/ koniocellular
    • magnocellular: lower two layers of LGN
    • parvocellular: top 4 LGN layers
    • koniocellur: ventral to each layer
  55. primary sensory cortex
    • the area of sensory cortex that receives most of its input directly from
    • the thalamic relay nuclei of that system. For instance, the primary visual
    • cortex is the area of the cerebral cortex that receives most of its input from
    • the lateral geniculate nucleus of the thalamus.
  56. secondary sensory cortex
    • comprises the areas of the sensory cortex that receive most
    • of their input from the primary sensory cortex of that system or from other
    • areas of the secondary sensory cortex of the same system.
  57. association cortex
    • any area of cortex that receives input from more than one sensory
    • system. Most input to areas of association cortex come from areas of secondary
    • sensory cortex.
  58. Parallel systems
    • ystems in which information flows through the components over multiple
    • pathways. Parallel systems feature parallel processing, the simultaneous analysis
    • of a signal in different ways by the mulitpl eparallel pathways of a neural
    • network.
  59. frontal operculum
    • the area of frontal lobe cortex that lies just in front of the face area of the primary motor cortex. in the left hemisphere it is the location of brocas area.
    • anatomical assymetry b/w hemispheres
  60. planum temporale
    posterior region of lateral fissure; role in comprehension of language (wernicke's area)
  61. heschl's gyrus
    lateral fissure anterior to planum temporale in temporal lobe- location of primary auditory cortexes
  62. process of auditory hearing w/in ear
    vibrations in stapes trigger vibration sof the oval window, which transfers vibration to the fluid of the cochlea. teh cochlea has an internal membrane called the organ of corti
  63. organ of corti
    auditory receptor organ
  64. basilar membrane/tectorial membrane
    • basilar membrane: auditory receptors are mounted here
    • tectorial membrane: rests on the hair cells
  65. round window
    vibrations of cochlear fluid are dissipated by round window, as elastic membrane in cochlea wall
  66. semicircular canals
    receptive orans of the vestibular system, which carries information about the direction and intensity of head movements, maintainting balance
  67. network of auditory pathways
    axons of each auditory nerve synapse in the ipsilateral cochlear nuclei, from which many projections lead to the superior olives on both sides of the brain stem at the same level the axons of the olivary neurons project via the lateral lemniscus to the inferior colliculi, where they synapse on neurons that project to the medial geniculate nuclei, which project to the primary auditory cortex. signals are transmitted to both ipsilateral and contralateral cortices.
  68. primary auditory cortex
    receives input from medial geniculate nucleus, located in temporal lobe, within lateral fissure. surround by "belt" of secondary cortex.
  69. primary auditory cortex organization
    functional columns. all neurons encountered tend to respond optimally to same-frequency sounds; organized tonotopically, on the basis of frequency
  70. where are auditory signals ultimately conducted to?
    association cortex: prefrontal cortex and posterior parietal cortex
  71. auditory cortex damage
    • complicated because most auditory cortex is in the lateral fissure; few permanent hearing deficits following lesions. system is partially contralateral.
    • -conductive deafness: ossicle damage
    • -nerve deafness: cochlea/auditory nerve
  72. free nerve endings
    simplest cutaneous receptors; neuron endings with no specialized structures. sensitive to temperature change and pain
  73. two major somatosensory pathways
    • dorsal column medial lemniscus system: touch and prioception
    • -enter via a dorsal root
    • -ascend ipsilaterally in dorsal columns
    • -synapse in dorsal column nuclei of medulla
    • -decussate and ascend in medial lemniscus to contralateral ventral posterior nucleus of thalamus
    • -also input from trigeminal nerve
    • -most neurons project to primary somatosensory cortex

    anterolateral: pain and temporature
  74. bimodal neurons
    posterior parietal cortex: respond to activation of 2 different sensory systems (somatosensory and visual)
  75. hemianopsia
    a scotoma covers half the visual field
  76. somatosensory agnosia (2 types)
    1. asterognosia: inability to recognize objects by touch

    2. asomatognosia: inability to reconize parts of one's own body (unilateral-left side) damage to right posterior parietal
  77. paradox of pain
    • 1) adaptiveness of pain: important for survival
    • 2) lack of clear cortical representation of pain- areas of activation vary from person to person. removal of somatosensory cortex to not change the threshold for pain.
    • 3) descending pain control: pain can be supressed by cognitive and emotional factors
  78. gate control theory
    ability of cognitive and emotional factors to block pain; signals coming from brain can activate neural gating circuits in spinal cord to block incoming pain signals
  79. cortical area most associated with pain
    anterior cingular cortex (cortex of anterior cingulated gyrus) -EMOTIONAL reaction to pain rather than the perception of pain itself
  80. the chemical senses
    olfaction and gustation; function is to mnitor the chemical content of the environment.
  81. phemones
    chemicals that influence the physicology and behavior of others in the same species
  82. olfactory receptors
    upper part of the nose, dendrites in nasal passages. axons pass through skull enter olfactory bulbs, synapse on neurons thea tproject via olfactory tracts to the brain
  83. one olfactory receptor one neuron rule
    each olfactory receptor cell contains only one type of receptor protein molecule. receptors are scattered throughout olfactory mucosa,
  84. where does each olfactory tract project to?
    • medial/temporal lobes
  85. olfactory system is the only major sensory system whose major sensory pathway reaches the cerebral cortex without first passing through the
  86. two major olfactory pathways leaving the amygdala-piriform area
    • 1) projects diffusely to limbic system
    • 2) projects via medial dorsal nuclei to orbitofrontal cortex
  87. gustatory system
    • taste receptors (clusters of 50) located around papillae
    • do not have their own axons; each neuron that carries impulses away from ataste bud receives input from many receptors
  88. anosmia/ageusia
    • anosmia: inability to smell
    • ageusia: inability to taste
  89. selective attention
    we can only perceive a small amount of the many stimuli that excite our sensory organs at any time; ignore the rest
  90. properties of light
    • wavelength: perception of color
    • intensity: perception of brightness
  91. binocular disparity
    difference in position of the same image on two retinas
  92. retina layers
    • -receptors
    • -horizontal cells
    • -bipolar cells
    • -amacrine cells
    • -retinal ganglion cells
  93. retinal ganglion cells
    axons project across teh inside of th retina before gathering in a bundle and leaving eyeball (through blind spot)
  94. amacrine and horizontal cells
    lateral communication: communication across the major channels of sensory input
  95. "inside out" arrangement
    light reaches receptors after passing through the other four layers, then the message goes back through the layers to the retinal ganglion cells, then through those axons in a bundle out of the eyeball
  96. problems with inside out arrangement
    • 1) incoming light is distorted by retinal tissue it has to first pass through
    • -fovea helps: indentations specialized for high acuity, retinal ganglion layer in very thin here
    • 2) for bundle of retinal ganglion axons to exit eyeball t here must be a blind spot
    • -completion: filling in. visual system fills in gaps in retinal images
  97. surface interpolation
    how we perceive surfaces; visual system extracts information about edges and fills it in
  98. convergence: rods/cones
    retinal ganglion cells may receive signals from hundreds of diff. rods, but signals from only a few cones. effect of dim lighting stimulating tons of rods can summate in the firing of a retinal ganglion cell when the same stimulation in cones does not summate to the same degree
  99. cones and rods distribution on retina
    • only cones in fovea, no rods
    • more rods in nasal hemiretina than temporal hemiretina
  100. spectral sensitivvity
    lights of same intensity but different wavelengths differ in brightness due to visual system not being equally sensitive to all wavelengths in the visual spectrum
  101. spectral sensitivity curve
    • a graph of the relative brightness of lights of the same intensity at different wavelengths
    • -visual system is most sensitive to wavelengths (yellow, bright warm colors) - will look the brightest
    • -in scotopic conditions, most sensitive to cool blue/violet colors
  102. purkinje effect
    • before dusk, yellow and red flowers seem brighter than blue ones
    • at night, blue flowers seem brighter than yellow
  103. how do we see color and acuity when cones are crammed into fovea at center of visual field?
    eyes continuously scan the visual field, and our visual perception at any instant is the summation of recent visual information (TEMPORAL INTEGRATION)
  104. fixational eye movements
    • tremor
    • drifts
    • saccades: small jerky movements
    • visual neurons respond to change
  105. rhodopsin
    • g protein receptor responding to light rather than neurotransmitters.
    • rods are in darkness: sodium channels are partially open which keeps them slightly depolarized, allows a steady flow of excitatory glutamate to come from them
    • light: series of events closes sodium channels and hyperpolarizes the rods, reducing release of glutamate
  106. retinal geniculate striate pathways
    • conduct signals from each retina to primary visual cortex via lateral geniculate nuclei of the thalamus
    • 90 percent of axons become part of RGS pathways; no other sensory system has such a predominant pair of pathways
  107. lateral geniculate nuclei
    6 layers, each layer receiving input ffrom all parts of the contralateral visual field (three from one eye, three from the other)
  108. retinotopic organization
    • RGS system
    • each level of the system is organized like amap of the retina
    • disproportionate representation of the fovea in the Primary visual cortex (25 %)
  109. M and P channels
    • two parallel channels of communication through each LGN
    • parvocellular: small cell bodies
    • -top 4 layers
    • -fien pattern details
    • -stationary, slow moving objects
    • -CONES

    • M layers
    • bottom two
    • movement
    • RODS
  110. edges
    • define extent and position of objects
    • perception of contrast between two adjacent areas of visual field
    • mach bands
  111. receptive fields of the RGS system
    • -receptive fields in th efoveal area of the retina were smaller than the periphery, consistent with high-acuity in fovea
    • -all neurons have circular receptive fields
    • -all neurons were monocular (field in one eye)
    • -excitatory and inhibitory area
  112. one function of neurons in RGS System
    respond to degree of brightness contrast between 2 areas in receptive field
  113. columnar organization of primary visual cortex
    • 1) characteristics of receptive fields can be attributed to flow of signals from neurons with simpler receptive fields to more complex. on center/off center in lower layer IV---simple cells---complex cells
    • 2) primary visual cortex neurons are grouped in functional vertical columns
  114. ocular dominance colummns
    alternating areas of left eye and right eye dominance
  115. implications of plasticity in visual system
    • -research on reactions to simple stimuli cannot provide a complete explanation of how visual system works
    • visual neurons are plastic, capable of changing structure/function
    • -receptive field properties of each neuron change with the elements in the scene
  116. component/trichromatic theory of color vision
    • three different types of cones, each with a differetn spectral sensitivity
    • color of stimulus is encoded byt he ratio of activity in three kinds of receptors
    • three is the minimum number of different wavelengths needed to match every color
  117. opponent process theory of color vision
    • two different classes of cells- BRIGHTNESS v COLOR
    • each classes encoded two complementary color perceptions
    • -red: hyperpolarization green:hypopolaraization
    • complementary colors: produce white or gray when combined in equal measures
  118. color constancy
    perceived color of an object is not a simple function of the wavelengths reflected; its the tendency for an object to stay the same color despite changes in the waelengths of light that it reflects
  119. retinex theory
    color of an object is determined by its reflectance; proportion of light of diff wavelenghts that a surface reflects. efficiency in ABSORBING each wavelength and reflecting unabsorbed does not change
  120. dual opponent color cells
    • respond ON when center is illuminated with one wavelength and suround is stimulated with another wavelength
    • respond OFF when pattern is reversed

    not evenly distributed; concentrated in BLOBS
  121. blobs
    • cytochrome oxidase
    • columsn
    • dual opponent color cells
  122. what happens as you move up primary visual---secondary---association cx
    • larger receptive fields
    • stimuli to which neurons respond are more specific/complex
  123. blindsight
    • damage to the PVC
    • ability to respond to visual stimuli in scotomas even though they have no conscious awareness
    • Perception of MOTION most likely to survive damage
  124. dorsal stream versus ventral stream
    • dorsal: primary visual---- dorsal prestriate cortex----posterior parietal cortex
    • SPATIAL STIMULI (location/direction of movement)
    • ventral: primary visual----ventral prestriate cortex---inferotemporal cortex
  125. control of behavior v. conscious perception
    • dorsal: behavioral interactions w/objects (visually guided behavior)
    • ventral: mediate conscious perception of objects