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anat 312 > lecture 17 > Flashcards

lecture 17 Flashcards

1
Q

what is the cerebral cortex?

A

thin sheet of neurons and their interconnections

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2
Q

the cerebral cortex is organized into ____ and ____ to ____________?

A

gyri, sulci, increase the surface area

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3
Q

evoluntionarily, the cerebral cortex has increased in both ____ and ____ due to ____________?

A

size of hemispheres, area of cerebral cortex, its role in language and abstract thinking

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4
Q

what are the areas of the cerebral cortex?

A
  • paleocortex (old)
  • archicortex (begining)
  • neocortex (new)
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5
Q

what is encompased by the paleocortex?

A

some of the base of the telencephalon

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6
Q

what is encompased by the archicortex?

A

hippocampus

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7
Q

what is encompased by the neocortex?

A

what can be seen on the outside of the brain - 95% of total cortical area in primates

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8
Q

what are the 2 cell types of the neocortex?

A

pyramidal cells and non-pyramidal cells

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9
Q

describe pyramidal cells

A
  • most numerous cell type and principal output neuron of neocortex
  • named after shape
  • have long axons to reach other cortical areas/subcortical areas where they synapse
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10
Q

what are Betz cells?

A
  • giant pyramidal cells in neocortex

- axons can project several feet to the spinal cord

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11
Q

where can Betz cells be found?

A

corticospinal, corticobulbar and corticothalamic tracts

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12
Q

describe non-pyramidal cells

A
  • granule (stellate) cells
  • principle interneurons
  • varied shapes
  • multipolar
  • short axons that remain in the cortex
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13
Q

the neocortex is subdivided into a ___ layered structure?

A

6

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14
Q

what are the 6 layers?

A

(1) molecular layer
(2) external granular layer
(3) external pyramidal layer
(4) internal granular layer
(5) internal pyramidal layer
(6) multiform layer

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15
Q

describe the molecular layer

A
  • cell poor layer

- contains axons and dendrites of neurons from deeper layers

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16
Q

describe the external granular layer

A

projects to other areas of the cortex and is thought to participate in higher cognitive function

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17
Q

describe the external pyramidal layer

A

projects to other areas of the cortex and is though to participate in higher cognitive function

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18
Q

describe the internal granular layer

A

receives input from the thalamus

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19
Q

describe the internal pyramidal layer

A

output layer that sends information from the cortex to the brainstem, spinal cord, and basal ganglia

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20
Q

describe the multiform layer

A
  • made of fusiform shaped, modified pyramidal cells

- projects to the thalamus

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21
Q

what are minicolumns?

A

cells in the layers of the neocortex line up in columns perpendicular to the sheets of cells

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22
Q

describe how the neurons within minicolums will synapse

what is the result?

A

they synapse with those in layers above and below, forming a functional unit

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23
Q

are the layers equally prominent throughout the neocortex?

A

no

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24
Q

describe the distribution of layers throughout the granular neocortex

A

layers 2-5 are dominated by small granule and pyramidal cells

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25
Q

the lack of what makes the granular cortex look like on continuous layer? provide an example

A

large pyramidal cells

-e.g. primary sensory areas

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26
Q

describe the distribution of layers throughout the agranular neocortex

A
  • layers 2-5 are dominated by large pyramidal cells

- smaller granule cells appear minor in comparison

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27
Q

provide an example of agranular neocortex

A

primary motor area

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28
Q

what is the result of the differing size and types of cells across cortical areas?

A

can see a difference in thickness of the neocortex (1.5-4.5 mm)

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29
Q

what is the thickest cortical area?

A

precentral gyrus (primary motor area)

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30
Q

what Is the thinnest cortical area?

A

postcentral gyrus (primary somatosensory area)

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31
Q

what are Brodmann’s areas?

A
  • 52 functionally and organizationally distinct regions of the cortex
  • developed by Korbinian Broadman in 1909
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32
Q

what is BA4?

A

primary motor cortex

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33
Q

where is BA4 located?

A

anterior wall of central sulcus, tapering the strip of the precentral gyrus

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34
Q

BA4 is the _____ cortex of the brain

A

thickest

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35
Q

describe the cells of BA4

what do they give rise to?

A
  • contains Betz cells
  • these extend to the spinal cord where they synpase on motor neurons
  • gives rise to much of the corticospinal tract
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36
Q

what is unique about BA4 cells?

A

85% of fibers cross to the opposite side of the body

decussation of the pyramids

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37
Q

how are BA4 cells organized?

A

somatotopically
-anatomical map of the body is based on the areas of the cortex that process those motor functions - areas with more intricate motor functions have a larger representation in the cortex

38
Q

what is the function of BA4?

A

generate impulses that control the execution of movement for the opposite side of the body (inititation of movement)

39
Q

what would be the result of a lesion to BA4?

A

hemiparesis of the opposite side

40
Q

what is BA6?

A

premotor and supplementary motor area

41
Q

where is the premotor area located?

A

anterior to the primary motor cortex (BA4) on lateral surface of hemisphere

42
Q

what is the function of the premotor area?

A

externally (sensory) guided movement (e.g. catching a ball)

43
Q

where is the supplementary motor area located?

A

anterior to the primary motor cortex, dorsal to the premotor area, and extends medially to the surface of the hemisphere

44
Q

what are the functions of the supplementary motor area?

A
  • internally guided movement
  • sequence of learned actions
    (e. g. playing piano)
45
Q

what would be the result of a lesion to BA6?

A

problems preforming purposeful, coordinated movement (apraxia)

46
Q

what is BA8?

A

frontal eye field

47
Q

where is BA8 located?

A

medial surface of hemisphere, anterior to the motor cortex

48
Q

what are the functions of BA8?

A
  • controls eye movements

- generates saccades in contralateral direction via connection to contralateral paramedian pontine reticular formation

49
Q

what would be the result of a lesion to BA8?

A

impaired eye movement in contralateral direction

50
Q

what is BA 44&45?

A

Broca’s area

51
Q

where are BA 44&45 located?

A

inferior to frontal gyrus, on the left side in most individuals

52
Q

what is the function of Broca’s area?

A

production of written and spoken language

53
Q

what would be the result of a lesion to BA44/45?

A

broca’s aphasia

  • nonfluent aphasia
  • trouble producing language
  • no issues with comprehension of language
54
Q

what is BA 1,2&3?

A

primaey somatosensory area

55
Q

what is a unique feature of BA 1,2&3?

A

somatotopically organized

56
Q

where is BA 1,2&3?

A

three parallel strips in the parietal lobe
BA1: postcentral gyrus
BA2: on anterior wall of postcentral gyrus
BA3: on posterior wall of the central sulcus

57
Q

what is the function of BA 1,2,&3?

A

initial processing of touch, pain, temperature sense ans proprioception for opposite site of the body

58
Q

what is the pathway for BA 1,2&3?

A

medial lemniscus and spinothalamic tracts –>
relay in ventral posterolateral nucleus –>
projects through posterior limb of internal capsule to BA 3, then 1, then 2

59
Q

what is BA 5&7?

A

somatosensory association area

60
Q

where is BA 5&7?

A

ventral to the primary somatosensory cortex

61
Q

what are the functions of BA 5&7?

A
  • orientation of objects to self and other objects by touch

- oject recognition by touch

62
Q

what would be the result of a lesion to BA 5&7?

A

inability to recognize objects based on touch (called asterognosis, or tactile agnosia if one sided)

63
Q

what is BA 17?

A

primary visual cortex

64
Q

where is BA 17?

A

medial surface of hemispheres, surrounding the calcarine sulcus, extends slightly to occipital lobe

65
Q

what is the function of BA 17?

A

communicated informatoin about contralateral visual field

66
Q

what is the primary visual pathway?

A

optic nerve –> optic chiasm –> lateral geniculate nucleus (in the thalamus) –> banks of calcarine sulcus

67
Q

what is a unique feature of BA 17?

A

retinotopic organization

68
Q

explain retinotopic organization

how does this impact the way information from the visual field is projected onto the calcarine sulcus?

A
  • image from visual field is flipped vertically and horizontally onyl the retina and projected to the primary cortex
  • information from upper part of visual field is projected to lower banks of calcarine sulcus
  • information from lower part of visual field is projected to upper banks of calcarine sulcus
69
Q

what would be the result of a lesion to BA 17?

A

cortical blindness

  • total or near loss of conscious awarness of visual stimuli
  • information cannot be turned into meaningful input
70
Q

what is BA 18&19?

A

visual association cortex

71
Q

where is BA 18&19?

A

surrounds BA 17, occupies the remainder of the occipital lobe, and extends into temporal lobe

72
Q

what is the function of BA 18/19?

A

higher order processing of information from primary visual cortex to recognize features as objects or people

73
Q

what is BA 41?

A

primary auditory cortex

74
Q

where is BA 41?

A

superior surface of the temporal lobe and transverse temporal gyri

75
Q

what is the function of BA41?

A

perception of sound (frequency)

76
Q

what is unique to BA41?

A

tonotropic organization

77
Q

explain tonotropic organization

A

auditory information is projected to the primary auditory cortex tonotopically - layout of neurons in based on the frequency of sound

78
Q

where is auditory information from BA 41 relayed?

A

medial geniculate nucleus

79
Q

what would be the result of a lesion to BA 41?

A

unilateral lesions do not affect hearing bc of bilateral representation

80
Q

what are BA 42 & 22?

A

auditory association areas

81
Q

where are BA 42 & 22 located?

A

inferior to BA 41, forms most of superior temporal gyrus

82
Q

what is the function of BA 42/22?

A

aids in the perception of auditory inputs (necessary to recognize sounds)

83
Q

what would be the result of a lesion to BA 42/22?

A

can still hear sounds but unable to tell the difference btwn them

84
Q

what is part of BA 22?

A

Wernicke’s area

85
Q

where is Wernicke’s area located?

A

posterior aspect of superior temporal gyrus

on left side in most people

86
Q

what is teh function of Wernicke’s area?

A

required for understanding written and spoken language

87
Q

what would be the result of a lesion to Wernicke’s area?

A
  • fluent aphasia
  • ability to produce written and spoken word
  • words/sequences have little to no meaning
  • trouble comprehending language (written and spoken)
88
Q

describe hemispheric specialization

A

-left side of cerebral cortex is the dominant hemisphere in 95% of right handed people and 60-70% of all ppl
-left handed people who are not left brain dominant can be either right brain or bilateral
^these people will recover faster from damage to lesions of language centers

89
Q

what functions are associated with the left brain?

A
  • language (broca’s and wernicke’s)
  • skilled complex motor tasks
  • detailed analytical abilities
  • logic and problem solving
90
Q

what functions are associated with the right brain?

A
  • complex visual-spatial skills
  • music perception
  • imparting emotional significance to events and language
  • creativity and imagination
91
Q

describe structural asymmetries using planum temporale as an example

A

planum temporale is the heart of wernicke’s area - leftward asymmetry is seen in 60-70% of people, atypical (rightward) asymmetry has been correlated to familial risk of dyslexia

anat 312 (18 decks)

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