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Neuropsych > Chapter 11 > Flashcards

Chapter 11 Flashcards

1
Q

cerebral asymmetry

A

anatomical, physiological, or behavioral differences between the two cerebral hemispheres

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2
Q

laterality

A

two cerebral hemispheres have separate functions

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3
Q

challenges to studying cerebral asymmetry

A
  1. laterality is relative
    • both hemispheres participate in nearly every behavior
  2. environmental and genetic influence on laterality
    • cerebral organization of some left handers and females appears less asymmetrical than that of right-handers in males
  3. a range of animals with asymmetrical brains
    • songbirds, rats, cats, and monkeys
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4
Q

major anatomic differences between two hemispheres

A

identified with MRI

  1. rt hemi: slightly larger and heavier; lt hemi: contains more gray matter (neurons)
  2. temporal lobes: specialization
    1. left: language
    2. right: music functions
  3. temporal lobe & thalamus:
    • anatomical asymmetry in the temporal lobe’s cortex correlates with an asymmetry in the thalamus
    • structural asymmetry compliments apparent functional asymmetry of the thalamus
    • left thalamus, like left hemi, also dominant for language functions
  4. frontal operculum (Broca’s area):
    • organized differently on left and right hemisphere
    • left side: area of cortex buried in the sulci is greater
      • grammar production
    • right side: area visible on surface is 1/3 larger
      • tone of voice (prosody)
    • lateralization of the functions
  5. lateral fissure: slope of lateral fissure is gentler on the left hemisphere than on the right
    • tempororparietal cortex lying ventral to lateral fissure appears larger on the right
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5
Q

neocortical asymmetry

describe

A
  • overall neocortical surface area was the same in both hemispheres
  • rt hemisphere: extends further anteriorly than the left
  • lt hemisphere: extends farther posteriorly than the right
  • overall pattern of asymmetry is evident across both hemispheres
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6
Q

neocortical asymmetry

largest asymmetry favored

A
  • left hemi: in Sylvian and medial temporal regions
  • right hemi: in posterior parietal and dorsal lateral pre-frontal areas
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7
Q

neocortical asymmetry

occipital horns of the lateral ventricles

A

5x likely to be longer on the right side than on the left

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8
Q

neuronal asymmetries

A
  • dendritic fields of pyramidal cells have abundant branches in Broca’s area (left frontal operculum)
  • neurons in each region have a distinct pattern of the dendritic branching
    • important bc: each branch is a potential location for enhancing or suppressing neuronal communication → more branch points = cells w more degrees of freedom w respect to function
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9
Q

gene asymmetries

A
  • human genome project
  • genes expressed differently in the two hemispheres
    • epigenetic changes mimic their relationship between genes
    • experience may differentially influence the two hemispheres
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10
Q

lateralized =

A

= dissociated

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11
Q

double dissociation

A
  • two neocortical areas are functionally dissociated by two behavioral tests
  • performance on each test is affected by a lesion in one zone but not in the other
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12
Q

hemisphere double dissociation ex

A
  • left-hemi lesions: (rt-handed patients) produce deficits in language functions – speech, writing, and reading, that are not produced by right-hemisphere lesions
    • → the two hemispheres’ functions are dissociated
  • rt hemi lesions: performing spatial tasks, singing, playing musical instruments, and discriminating tonal patterns,
  • Because a right-hemisphere lesion disturbs tasks that are not disrupted by left-hemisphere lesions and vice versa, the two hemispheres are doubly dissociated.
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13
Q

case study: double dissociation

conclusion

A
  • Subsequent to removal of the left temporal lobe, PG was impaired only on verbal tests
  • Subsequent to removal of the right temporal lobe, SK was impaired only on nonverbal tests.
  • Both patients performed normal on many tests providing evidence for localization as well as for lateralization of functions
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14
Q

case study: double dissociation

PG

A
  • patient A, PG
  • 31 yo man, developed seizures in 6th year preceding neurosurgery, seizures poorly controlled by medication and subsequent neurological investigations revealed large tumor in anterior part of left temporal lobe
  • preoperative tests: superior intelligence, significant deficits in verbal memory
  • left temporal lobectomy
    • decreased intelligence ratings
    • further decreased verbal memory scores
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15
Q

case study: double dissociation

SK

A
  • patient B, SK
  • preoperative scores: low score on recall of complex drawing
  • right temporal lobectomy
    • decreased intelligence ratings
    • decreased nonverbal memory scores for simple and complex designs
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16
Q

commissurotomy

A
  • surgical disconnection of the two hemispheres by cutting the corpus callosum
  • to prevent the spread of a seizure when meds fail
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17
Q

epileptic seizures

A

may begin in a restricted region of one hemisphere and spread through the fibers of the corpus callosum, the commissure, to the homologous location in the opposite hemisphere

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18
Q

after commissurotomy

A

split brain

  • two hemisphere independent, can’t communicate
  • each receives sensory input from all sensory system and each can control body’s muscle
  • sensory info can be presented to one hemisphere, and its function can be studied without the other hemi having access
  • right hemi: reasonably good recognition ability, but cannot initate speech (bc lacks access to speech mechanisms in left)
    • have a physical key → they can grab it
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19
Q

how vision is affected by split brain

A
  • input from left visual field goes to right hemi
  • input from right visual field goes to left hemi
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20
Q

how speech is affected by split brain

A
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21
Q

when left hemi of split brain pt has access to info

A

it can initiate speech and communicate about the info

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22
Q

when right hemi of split brain pt has access to info

A

can recognize but cannot initiate speech

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23
Q

split brain patients - faces

A
  • unaware of the gross discordance between the pictures two sides
  • right hemisphere plays special role in recognizing faces
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24
Q

tachistoscope

A
  • visual info can be presented to each visual field independently
  • information presented to only one visual field is processed most efficiently by the hemisphere specialized to receive it
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25
Q

CSA injection

non speech hemi

A

may produce no speech arrest or only brief arrest

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26
Q

Stimulation CSA Injection

sodium amobarbital injection (wada test)

A

inject sodium amobarbital into carotid artery to produce brief period of anesthesia of ipsilateral hemisphere

  • advantage: each hemi can be studied separately
  • patients with anesthesia of either hemisphere are totally nonresponsive to visual stimulation to the contralateral visual field
    • about 98% of right-handers and 70% of left-handers show speech disturbance after sodium amobarbital injection into the left hemisphere, but not after injection into the right hemisphere
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27
Q

CSA innjectionn

speech hemi

A
  • results in unequivocal localization of speech bc injection into the speech hemi arrests speech for up to several minutes
  • as speech returns, characterized by aphasic errors
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28
Q

brain stimulation

A

stimulation: to identify speech and movement areas and to localize the extent of a tumor or epileptogenic tissues

surgeon stimulates exposed cortex and records conscious patient’s responses

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29
Q

stimulation of left hemi

A

can block the ability to speak

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30
Q

stimulation of right hemi

A

does not block ability to speak

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31
Q

behavioral asymmetries

A

a specific behavioral symptom associated with damage does not necessarily mean that the region controlled the disrupted function

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32
Q

visual system

behavioral asymmetries

A

present each hemisphere selectively with specific visual information - completely crossed

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33
Q

auditory system

behavioral asymmetries

A
  • not completely as crossed as visual bc both hemis recieve projections from each ear
  • crossed auditory connections are more numerous and more rapidly conducting than ispilateral projections
  • left ear superiority
    • perception of melodies
  • left hemi
    • specialized for processing language related sounds
  • right hemi
    • specialized for processing music related sounds
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34
Q

auditory system

left ear superiority

A

perception of melodies

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35
Q

auditory system

left hemi

A

specialized for processing language related sounds

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36
Q

auditory system

right hemi

A

specialized for processing music related sounds

37
Q

dichotic listening tasks

A
  • subjects recalled more digits that had been presented to the right ear than to the left
  • → when different stimuli are presented simultaneously to each ear, the pathway from the right ear to the speaking hemisphere has preferred access (and ispilateral pathway from left ear is relatively suppressed
38
Q

somatosensory system

behavioral asymmetries

what kind of tasks

A
  • almost completely crossed → allows easy behavioral comparison
  • left hand of rt handed participants is superior at nearly all tasks of recognizing shapes, angles, patterns
  • blind and sighted participants read braille more rapidly with left hand
    • spatial info for rt hemi
39
Q

challenges of laterality studies

A
  1. behavioral measures of laterality do not correlate perfectly with direct measures of cerebral asymmetry
  2. strategies can alter performance significantly
  3. participants’ preconceived biases may affect performance
  4. laterality effects may be a result of experience rather than biological factors
40
Q

specialization theory

A
  • unique functions for each hemisphere
  • extreme unilateral specialization model
    • only one hemisphere facilitates a given psychological process
  • other models
    • the two hemis might process info in distinctly different ways
41
Q

interaction theory

A
  1. cooperation between each hemi
  2. hemispheres function simultaneously, but work on different aspects of the same processing
    1. although the 2 hemis have the capacity to performa a given function, they may inhibit or suppress each other’s activity
  3. either the two hemis receive info preferentially and thus perform different analyses simultaneously or some mech enables each hemi to pay attention to specific types of info → leading to different hemispheric analysis
42
Q

anatomical, physiological, or behavioral differences between the two cerebral hemispheres

A

cerebral asymmetry

43
Q

two cerebral hemispheres have separate functions

A

laterality

44
Q
  1. laterality is relative
    • both hemispheres participate in nearly every behavior
  2. environmental and genetic influence on laterality
    • cerebral organization of some left handers and females appears less asymmetrical than that of right-handers in males
  3. a range of animals with asymmetrical brains
    • songbirds, rats, cats, and monkeys
A

challenges to studying cerebral asymmetry

45
Q
  • although the overall neocortical surface area was the same in both hemispheres, an overall pattern of asymmetry exists throughout the brain
  • rt hemisphere: extends further anteriorly than the left
  • lt hemisphere: extends farther posteriorly than the right
A

neocortical asymmetry

46
Q
  • dendritic fields of pyramidal cells in Broca’s area (left frontal operculum) with those in facial area of the motor cortexin the left precentral cortex compared to right:
  • neurons in each region have a distinct pattern of the dendritic branching
  • important bc: each branch is a potential location for enhancing or suppressing neuronal communication → more branch points = cells w more degrees of freedom w respect to function
A

neuronal asymmetries

47
Q
  • human genome project
  • genes expressed differently in the two hemispheres
    • epigenetic changes mimic their relationship between genes
    • experience may differentially influence the two hemispheres
A

gene asymmetries

48
Q

= dissociated

A

lateralized =

49
Q
  • two neocortical areas are functionally dissociated by two behavioral tests
  • performance on each test is affected by a lesion in one zone but not in the other
A

double dissociation

50
Q
  • Subsequent to removal of the left temporal lobe, PG was impaired only on verbal tests
  • Subsequent to removal of the right temporal lobe, SK was impaired only on nonverbal tests.
  • Both patients performed normal on many tests providing evidence for localization as well as for lateralization of functions
A

case study: double dissociation

conclusion

51
Q
  • surgical disconnection of the two hemispheres by cutting the corpus callosum
  • to prevent the spread of a seizure when meds fail
A

commissurotomy

52
Q

may begin in a restricted region of one hemisphere and spread through the fibers of the corpus callosum, the commissure, to the homologous location in the opposite hemisphere

A

epileptic seizures

53
Q
  • two hemisphere independent, can’t communicate
  • each receives sensory input from all sensory system and each can control body’s muscle
  • sensory info can be presented to one hemisphere, and its function can be studied without the other hemi having access
  • right hemi: reasonably good recognition ability, but cannot initate speech (bc lacks access to speech mechanisms in left)
    • have a physical key → they can grab it
A

after commissurotomy

split brain

54
Q
  • input from left visual field goes to right hemi
  • input from right visual field goes to left hemi
A

how vision is affected by split brain

55
Q
A

how speech is affected by split brain

56
Q

it can initiate speech and communicate about the info

A

when left hemi of split brain pt has access to info

57
Q

can recognize but cannot initiate speech

A

when right hemi of split brain pt has access to info

58
Q
  • unaware of the gross discordance between the pictures two sides
  • right hemisphere plays special role in recognizing faces
A

split brain patients - faces

59
Q
  • visual info can be presented to each visual field independently
  • information presented to only one visual field is processed most efficiently by the hemisphere specialized to receive it
A

tachistoscope

60
Q
  • results in unequivocal localization of speech
  • as speech returns, characterized by aphasic errors
  • injection into non speech hemi - may produce no speech arrest or only brief arrest
  • advantage: each hemi can be studied separately
  • patients with anesthesia of either hemisphere are totally nonresponsive to visual stimulation to the contralateral visual field
    • about 98% of right-handers and 70% of left-handers show speech disturbance after sodium amobarbital injection into the left hemisphere, but not after injection into the right hemisphere
A

Stimulation CSA Injection

sodium amobarbital injection (wada test)

61
Q

stimulation: to identify speech and movement areas and to localize the extent of a tumor or epileptogenic tissues

surgeon stimulates exposed cortex and records conscious patient’s responses

A

brain stimulation

62
Q

can block the ability to speak

A

stimulation of left hemi

63
Q

does not block ability to speak

A

stimulation of right hemi

64
Q
  • cannot speak, move right arm, see on the rt visual field
  • patient cannot speak or later report on the experience
A

injecting CSA left carotid artery

anesthetizes left hemi

65
Q
  • sensory and motor symptoms on the left
  • no speech disturbance unless the pts rt hemi is dominant for speech
A

injecting CSA right carotid hemi

66
Q

a specific behavioral symptom associated with damage does not necessarily mean that the region controlled the disrupted function

A

behavioral asymmetries

67
Q

present each hemisphere selectively with specific visual information - completely crossed

A

visual system

behavioral asymmetries

68
Q
  • not completely as crossed as visual bc both hemis recieve projections from each ear
  • crossed auditory connections are more numerous and more rapidly conducting than ispilateral projections
  • dichotic listening tasks
    • subjects recalled more digits that had been presented to the right ear than to the left
    • → when different stimuli are presented simultaneously to each ear, the pathway from the right ear to the speaking hemisphere has preferred access (and ispilateral pathway from left ear is relatively suppressed
  • left ear superiority
    • perception of melodies
  • left hemi
    • specialized for processing language related sounds
  • right hemi
    • specialized for processing music related sounds
A

auditory system

behavioral asymmetries

69
Q

perception of melodies

A

auditory system

left ear superiority

70
Q

specialized for processing language related sounds

A

auditory system

left hemi

71
Q

specialized for processing music related sounds

A

auditory system

right hemi

72
Q
  • almost completely crossed → allows easy behavioral comparison
  • left hand of rt handed participants is superior at nearly all tasks of recognizing shapes, angles, patterns
  • blind and sighted participants read braille more rapidly with left hand
    • spatial info for rt hemi
A

somatosensory system

behavioral asymmetries

73
Q
  1. behavioral measures of laterality do not correlate perfectly with direct measures of cerebral asymmetry
  2. strategies can alter performance significantly
  3. participants’ preconceived biases may affect performance
  4. laterality effects may be a result of experience rather than biological factors
A

challenges of laterality studies

74
Q
  • unique functions for each hemisphere
  • extreme unilateral specialization model
    • only one hemisphere facilitates a given psychological process
  • other models
    • the two hemis might process info in distinctly different ways
A

specialization theory

75
Q
  1. cooperation between each hemi
  2. hemispheres function simultaneously, but work on different aspects of the same processing
    1. although the 2 hemis have the capacity to performa a given function, they may inhibit or suppress each other’s activity
  3. either the two hemis receive info preferentially and thus perform different analyses simultaneously or some mech enables each hemi to pay attention to specific types of info → leading to different hemispheric analysis
A

interaction theory

76
Q

5x likely to be longer on the right side than on the left

A

neocortical asymmetry

occipital horns of the lateral ventricles

77
Q
  • left hemi: in Sylvian and medial temporal regions
  • right hemi: in posterior parietal and dorsal lateral pre-frontal areas
A

neocortical asymmetry

largest asymmetry favored

78
Q
  • results in unequivocal localization of speech bc injection into the speech hemi arrests speech for up to several minutes
  • as speech returns, characterized by aphasic errors
A

CSA innjectionn

speech hemi

79
Q

may produce no speech arrest or only brief arrest

A

CSA injection

non speech hemi

80
Q
  • subjects recalled more digits that had been presented to the right ear than to the left
  • → when different stimuli are presented simultaneously to each ear, the pathway from the right ear to the speaking hemisphere has preferred access (and ispilateral pathway from left ear is relatively suppressed
A

dichotic listening tasks

81
Q

X hemi lesions produce deficits in language functions,for example, speech, writing, and reading

A

left

82
Q

X hemi lesions disrupt spatial tasks, singing, playing musical instruments, and discriminating tonal patterns

A

right

83
Q

which hemi is larger and heavier?

A

rt hemi: slightly larger and heavier

84
Q

which hemi contains more gray matter?

A

contains more gray matter (neurons)

85
Q

structural asymmetry of lt and rt temporal lobes

A

lt: language
rt: music functions

86
Q

left thalamus function

A

structural asymmetry compliments apparent functional asymmetry of the thalamus

left thalamus, like the left hemisphere, is also dominant for language functions

87
Q

frontal operculum structural asymmetry

left vs right

A

(Broca’s area)

organized differently on left and right hemisphere

  • left side: area of cortex buried in the sulci is greater
    • grammar production
  • right side: area visible on surface is 1/3 larger
    • tone of voice (prosody)
88
Q

lateral fissure

structural asymmetry

A
  • lateral fissure: slope of lateral fissure is gentler on the left hemisphere than on the right
  • tempororparietal cortex lying ventral to lateral fissure appears larger on the right

Neuropsych (15 decks)

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