Cerebral Asymmetry Flashcards

1
Q

what does laterality mean?

A

the 2 hemispheres have separate functions

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2
Q

what is the left hemisphere specialized for and what does it control?

A

language, controls R side of body

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3
Q

what is the right hemisphere specialized for and what does it control?

A

spatial nonverbal info, controls L side of body

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4
Q

lateralization is ________, not absolute

A

relative`

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5
Q

what 2 factors influence how lateralized a skill is?

A

environmental and genetic factors

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6
Q

what is the planum temporale?

A

wernicke’s area

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7
Q

what is the frontal operculum?

A

Broca’s area

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8
Q

what is the hemispherical difference in the planum temporale on the superior temporal gyrus in MOST individuals?

A

planum temporale is larger in the LEFT hemisphere than in the right

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9
Q

which primary cortex (located adjacent to planum temporale) is usually larger in the right hemisphere?

A

primary auditory cortex

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10
Q

what is Heschel’s gyrus?

A

primary auditory cortex

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11
Q

what are the 8 hemispheric differences identified by MRI?

A

1) right hemisphere larger/heavier, but left hemisphere has more gray matter
2) anatomical differences btw the left and right temporal lobes may be related to their relative differences in language and music abilities respectively
3) anatomical differences in the thalamus are related to anatomical differences in the temporal lobe, with the left thalamus specialized for language (left thalamus bigger)
4) slope of lateral fissure is less angled in the left hemisphere than in the right
5) frontal operculum is organized different in the L and R hemispheres
6) there are asymmetries in the distribution of neurotransmitters
7) the R hemisphere extends father anteriorly, and the L hemisphere extends farther posteriorly (cerebral torque)
8) meta-analysis of 17,000 brains finds asymmetry patterns across 34 areas of the brain

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12
Q

neurons in different parts of the lobe have different patters of…

A

dendritic branching

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13
Q

in terms of neuronal asymmetry, the left operculum has…

A

more branching, more connections

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14
Q

why are left handers typically excluded from brain imaging studies of language?

A

their lateralization is less asymmetrical than right handers

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15
Q

can gene expression vary between hemispheres?

A

yes, some genes are expressed differently in the two hemispheres, with such differences being observed as early as 5 weeks postconception

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16
Q

how could differences in gene expression affect later anatomical and neuronal asymmetries?

A

it is possible that the differences in gene expression give rise to later anatomical and neuronal asymmetries

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17
Q

how was asymmetry in the brain initially observed?

A

in neurological patients, specifically epileptic patients. they had electrodes implanted into the brain for treatment, surgery, etc and observing the results of these medical investigations revealed much about the functioning of the brain

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18
Q

why is observing the asymmetries of neurological patients tricky?

A

because any functional localization or lateralization that is observed could actually be due to the result of brain changes in a clinical condition and therefore cannot be generalized to healthy brains

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19
Q

what was one early treatment for epilepsy (Dr. Walter Penfield)

A

to remove the cortex where seizures originated

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20
Q

what functions of the brain seem to be symmetrical?

A

motor control and sensation

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21
Q

what function of the brain seems to be asymmetrical?

A

language

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22
Q

right hemisphere has increased ________ functions compared with the left

A

perceptual

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23
Q

stimulation of the left frontal or temporal lobes facilitated ______ ________

A

speech production

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24
Q

what is double dissociation?

A

experimental technique that is used to show that a particular function is associated with a particular brain region

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25
Q

describe the double dissociation found in patients PG and SC?

A

PG: had a left temporal lobotomy
-memory quotient and verbal recall were diminished
-no change in nonverbal recall

SC: had a right temporal lobotomy
-performance IQ and non verbal recall diminished
-no change in verbal recall

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26
Q

what is a classical clinical example of double dissociation?

A

functioning of brocas and wernicke’s areas

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27
Q

what is true in about 98% of right-handers’ brains?

A

speech lateralization is in the left hemisphere

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28
Q

what would left hemisphere lesions produce in right handers?

A

consistent deficits in language such as speech, reading, writing

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29
Q

what would right hemisphere lesions produce in right handers?

A

spatial tasks (singing, picking out musical instruments, etc) are disrupted

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30
Q

what is a commissurotomy?

A

when the corpus callosum and anterior commissure are severed to prevent the spread of seizure activity between both hemispheres

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31
Q

what is the initial behavioural result of commissurotomy?

A

greatly reduced seizure activity

32
Q

what is the main effect of commissurotomy?

A

hemispheres function independently of each other and without access to the others’ sensations, thoughts, or actions.

33
Q

what is not affected by commissurotomy?

A

cortical connections with sensory and motor systems and their bodily receptors and effectors

34
Q

information presented in the ____visual field goes to the right hemisphere

A

left

35
Q

information presented in the ___ visual field goes to the left hemisphere

A

right

36
Q

after commissurotomy, brief presentation in just the left or right visual field presents the information to…

A

a single hemisphere, and information cannot be shared with the other hemisphere

37
Q

ex: when spoon is presented to R visual hemisphere, what happens?

A

information goes to the left hemisphere, which can talk, and the subject can verbally report seeing the spoon

38
Q

ex: when spoon is presented to L visual hemisphere, what happens?

A

information goes to the right hemisphere, which cannot talk, and subject cannot verbally report seeing the spoon but the left hand can pick it out of a lineup

39
Q

when a patient is presented with images in both visual fields and asked to choose an appropriate related image out of a lineup, what happens?

A

both left and right hands will select appropriate images, then when asked to explain why, left hemisphere will accurately explain why the right hand selected what it did and then make up a reason for the left hand’s choice even though it does not understand

40
Q

what is chimeric stimuli in terms of facial recognition?

A

two sides of a face impossibly put together

41
Q

what happens when split-brain patients are presented with improbably chimeric stimuli and are asked to choose the face they had seen in the original array of normal faces?

A

patients will choose the face that was presented to left visual field, because right hemisphere is stronger for nonverbal spatial stimuli and is better at facial recognition

42
Q

what takes place in the Wada test?

A

sodium amobarbital is injected in the femoral artery and will briefly anesthetize the ipsilateral hemisphere

43
Q

in the Wada test, what happens if sodium amobarbital is injected into the left hemisphere?

A

right limbs fall, aphasia (cannot continue counting)

44
Q

in the Wada test, what happens if sodium amobarbital is injected into the right hemisphere?

A

left limbs fall, but can continue counting

45
Q

what does the Wada test prove?

A

that language seems to be localized to the left hemisphere

46
Q

why is the Wada test no longer used?

A

dangerous, used to be injections into carotid artery

47
Q

in an intact brain, which hemisphere is better at language processing?

A

left

48
Q

in an intact brain, which hemisphere is better at facial recognition and processing visuospatial information?

A

right

49
Q

the auditory system is ____ ________ than the visual system

A

less differentiated

50
Q

the predominant and fastest input to the auditory cortex comes from the __________ ear

A

contralateral

51
Q

language stimuli presented to which ear/hemisphere are more memorable?

A

right ear, left hemisphere

52
Q

melodies presented to which ear/ hemisphere are more memorable?

A

left ear, right hemisphere

53
Q

in Kimura’s dichotic listening model, when sound is presented to just one ear, what happens?

A

both ipsilateral and contralateral pathways are formed

54
Q

in Kimura’s dichotic listening model, when sound is presented to both ears, what happens?

A

sound goes to be processed in contralateral side, ipsilateral representation is suppressed

55
Q

what happens in split-brain patients subjected to Kimura’s dichotic listening model?

A

they wont report hearing the syllable presented to the opposite ear, because signal cannot go contralaterally

56
Q

somatosensory input is…

A

almost completely crossed

57
Q

which hand has an advantage to reading braille, and why?

A

left hand, supports the specialization of the right hemisphere to recognizing and processing patterns

58
Q

when recognizing objects that were previously touched while blindfolded, there was a right hand advantage for ______ and a left hand advantage for _________

A

recognizing letters
recognizing other shapes

59
Q

damage to the left-hemisphere motor regions results in what?

A

apraxia, which is the loss of skilled fine movements

60
Q

studies that quantified movements while subjects manipulated blocks suggests what?

A

that the two hemispheres play a complementary role in controlling movements based on native hand preference

61
Q

what do observations of mouth movements while speaking suggest?

A

that such movements start on the right side, suggesting control by the left hemisphere

62
Q

which side of the face are emotions displayed more strongly on and why?

A

left side of the face, relating to the right hemisphere specialization for emotions

63
Q

in pianists, speaking disrupted playing with which hand?

A

right hand

64
Q

in pianists, humming disrupted playing with which hand?

A

left hand

65
Q

how can the laterality effects of dichotic listening be negated?

A

telling subject to focus on verbal information being presented to left ear

66
Q

PET and fMRI studies reveal what type of support for lateralization?

A

left hemisphere lateralization for language tasks

67
Q

what type of lateralization do changes in blood flow velocity support?

A

left hemisphere lateralization of language

68
Q

what do specialization theories suggest?

A

that different hemispheres have unique functions

69
Q

what does one extreme specialization theory suggest?

A

that left hemi is specialized for fine motor control and speech requires this very detailed motor control, so therefore speech is localized to left hemisphere because of the need for this motor control

70
Q

what do interaction theories suggest?

A

that one hemisphere may be better at a task, but both cooperate in performing the task. ie, two hemispheres both work on different parts of processing at the same time

71
Q

what is meant by preferred cognitive mode?

A

individual differences will cause people to usee one type of thought process instead of another (ex: some people prefer logic and math, others prefer looking at the larger picture, etc)

72
Q

what is cognitive set and how does it relate to lateralization?

A

the biases in how individuals approach problems, and can influence the results of tests of lateralization

73
Q

where is vocalization lateralized in frogs and salamanders?

A

left hemi

74
Q

what do bees show lateralization in?

A

learning odors associated with reward and remembering the associations

75
Q

what do many birds have a specialization for and where?

A

left hemisphere specialization for production of song

76
Q

what type of homologus asymmetries do chimpanzees exhibit?

A

asymmetries in the homologues of Broca’s and Wernicke’s areas that mimic those observed in humans

77
Q

in primates, some research suggests that…

A

right hemisphere is specialized for rapid unimanual movements and left hemisphere specialized for whole-body movements