UNIT 2: Cerebral Hemispheres Flashcards

1
Q

what divisions are included under the CNS

A

Cerebral cortex
cerebellum
diencephalon
brainstem
spinal cord

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2
Q

what divisions are included under the PNS

A

cranial nerves
spinal nerves

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3
Q

what are the 2 functional divisions of the NS

A

somatic and autonomic

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4
Q

somatic sys

A

aspects of bodily function under conscious and voluntary control (motor control sys and sensory sys)

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5
Q

autonomic sys

A

involuntary activities of visceral muscle (smooth muscle, glands) and maintenance of homeostasis

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6
Q

where does motor control arise in the somatic NS

A

from the precentral region of the cortex - descending motor tracts thru brainstem and spinal cord

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7
Q

what are the 2 divisions of the autonomic NS

A

sympathetic and parasympathetic

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8
Q

sympathetic NS

A

vasoconstriction, inc blood pressure, pupil dilation, cardiac acceleration - “flight, fight, fright”

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9
Q

parasympathetic NS

A

slowing heart rate, dec blood pressure, pupillary constriction - counteracts preparatory action of sympathetic sys - “energy saving”

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10
Q

where does the autonomic NS arise from aka controls from

A

prefrontal crotex, hypothalamus, thalamus, hippocampus, brainstem, cerebellum, spinal cord

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11
Q

functional unit of the NS

A

neuron aka communicating tissue… responds to stimulation w inc activity (excitation) or dec activity (inhibition)

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12
Q

3 types of neurons

A

sensory (afferent), motor (efferent), interneurons

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13
Q

sensory (afferent) neurons

A

classified by sensory properties - ex. mechanical, thermal, pain, visual, auditory, taste

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14
Q

motor neurons (efferent)

A

activate response in muscles or glands, known for long myelinated axons, differ by size/conduction velocity/myelination

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15
Q

interneurons

A

most common
communication bw other neurons
confined to CNS

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16
Q

white matter

A

collections of myelinated axons - in the CNS can be tracts/fibre tracts/ pathways/ peduncles/ fasciculus/lemniscus/ capsules/commissures - in the PNS can be nerve/nerve fascicles

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17
Q

Gray matter

A

neural tissue consisting of cells bodies - grouped into a cortex/nucleus/ganglion

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18
Q

at week 3 in development of the embryo what are the 3 cell layers

A

ectoderm, mesoderm, endoderm

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19
Q

ectoderm becomes

A

CNS and skin

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20
Q

mesoderm becomes

A

muscles

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21
Q

endoderm becomes

A

insides like digestive tract and lungs

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22
Q

what is neurulation

A

to develop the CNS/PNS there is a thickening of the ectoderm called the neural plate - cells migrate and proliferate to form the neural plate - notochord signals the dec of the neural plate to start happening

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23
Q

what does the neural plate further develop into

A

the neural folds and neural groove - creates a trough and folds come into contract to fuse w one another

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24
Q

what does the neural groove further develop into

A

neural tube and some of the cells break off to create neural crest cells (dorsal to neural tube) which becomes the PNS and meninges

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25
Q

spina bifida occurs because of

A

a lack of fusion of the neural tube

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26
Q

mesencephalon and rhombencephalon

A

spinal cord

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27
Q

prosencephalon becomes

A

cerebrum

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28
Q

telencephalon becomes

A

cerebrum… most neurons accumulating here

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29
Q

the diencephalon becomes

A

thalamus and third ventricle

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30
Q

cerebrum function

A

higher functions (cognition, language, memory)
integrates sensorimotor functions and perception

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31
Q

limbic system

A

regulates motivational and emotional states

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32
Q

basal ganglia

A

regulates motor movements and muscle tone

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33
Q

thalamus

A

mediates sensation to cerebral cortex

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34
Q

hypothalamus

A

regulates body functions such as temp, satiation, water balance, emotional behaviour, sexual response

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35
Q

cerebellum

A

regulates coordination of skilled movements

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36
Q

midbrain

A

mediates auditory and visual reflexes
maintains cortical arousal
houses cranial nerve nuclei

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37
Q

pons

A

houses cranial nerve nuclei

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38
Q

medulla

A

regulates respiration, phonation, heartbeat, blood pressure
regulates reflexes

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39
Q

how are the 2 symmetrical cerebral hemispheres organized in terms of gray and white matter?

A

external gray matter - cerebral cortex
internal white matter - fibre tracts (association, commissural, projection)
internal gray matter (basal ganglia, amygdala, hippocampal formation)

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40
Q

what is the cerebral cortex?

A

the thin rim of gray matter that covers the cerebral hemispheres - about 2-4 mm thick and contains billions of neurons

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41
Q

how many cell layers are in the cerebral cortex

A

6 cell layers

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42
Q

what is in layer I of the cerebral cortex

A

axons, glial cells

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43
Q

what is in the layer II of the cerebral cortex

A

many stellate and small pyramidal

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44
Q

what is in layer III of the cerebral cortex

A

some stellate and medium pyramidal

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45
Q

what is in layer IV of the cerebral cortex

A

densely packed stellate cells (sensory afferents)

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46
Q

what is in layer V of the cerebral cortex

A

large pyramidal cells only (motor efferents)

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47
Q

what is in layer VI of the cerebral cortex

A

stellate and pyramidal (back to thalamus)

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48
Q

5 lobes of the cerebral cortex

A

frontal, parietal, occipital, temporal, insular

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49
Q

what are the 3 main sulcus/fissure of the cerebral cortex

A

longitudinal fissure, central sulcus, lateral sulcus

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50
Q

what are brodmann’s areas? (BA)

A
  • Brodman examined cytoarchitecture of the cerebrum
  • labelled approx 50 diff areas based on function
  • can describe the function of the various regions as: primary regions, association regions (unimodal or multimodal), or limbic regions
  • aka mapped the brain based on the cell layers: where it is thick w sensory cells and where is it thick with motor cells
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51
Q

pyramidal cells refer to

A

motor cells aka motor efferents (carry signals from brain to PNS to initiate an action)

52
Q

stellate cells refer to

A

sensory cells aka sensory afferents (bring sensory info from outside world to brain)

53
Q

what are primary areas

A

have a 1 to 1 correlation w sensory and motor functions

54
Q

describe sensory primary regions

A

receive projections from thalamic nuclei - have a thick layer of IV (stellate cells)

55
Q

describe motor primary regions

A

send projections to motor nuclei - thick layer of V (pyramidal cells)

56
Q

what are association areas

A

neural signals are integrated and organized for purposeful plans

57
Q

unimodal

A

integrate info related to a single modality (ex. motor planning, auditory comprehension)

58
Q

multimodal

A

integrate multiple sensory inputs

59
Q

what are the 3 sulci of the frontal lobe

A

lateral fissure, central sulcus, precentral sulcus

60
Q

what are the 4 gyri of the frontal lobe

A

precentral gyrus, superior frontal, middle frontal, inferior frontal

61
Q

describe the primary motor cortex (M1)

A

located in the frontal lobe at the precentral gyrus which is BA4 …. origin of corticospinal and corticobulbar tracts, preponderance of pyramidal (motor cells), origin of simple motor acts

62
Q

what is the motor homunculus (somatotopic)

A

body is represented via the homunculus
- face, larynx, pharynx have large representation on lateral precentral gyrus
- involved in selection, preparation, initiation, and temporal sequencing of speech/mastication and other movements

63
Q

what are the 3 unimodal association regions of the frontal lobe

A

premotor cortex, supplementary motor area, inferior frontal gyrus

64
Q

premotor cortex

A

BA6, inferior
sensory guided movement, mirror neurons
organizing complex movements

65
Q

supplementary motor area

A

BA6, Superior and medial
internally-generated movement (making a decision to move)
planning and rehearsing movements
decision making about movement (ex. tongue elevation vs tongue protrusion)

66
Q

inferior frontal gyrus

A

BA 44/45
Planning and articulation of speech = Broca’s area

67
Q

what is the multimodal association region of the frontal lobe

A

prefrontal cortex

68
Q

prefrontal cortex

A

BA 8, 9, 10, 11, 12, 46
- Converging info from brain and thalamus
- higher cog processes (attention, memory, visuospatial processes, linguistic processes)
- executive functions (inhibition, accessing memory, planning and sequencing)

69
Q

what are the sulci of the parietal lobe

A

lateral sulcus, central sulcus, parieto-occipital

70
Q

what are the gyri of the parietal lobe

A

postcentral gyrus, supramarginal gyrus, angular gyrus

71
Q

what is the primary region of the parietal lobe

A

primary sensory cortex (S1)

72
Q

primary sensory cortex

A

located at postcentral gyrus -BA 3, 1, 2
- virtual lack of pyramidal cells (layer V); Predominance of granule cells (layer IV) which receive input from thalamus
- receives contralateral somatic sensation from body regions

73
Q

what is the sensory homunculus (somatotopic)

A

primary sensory cortex is mapped as a homunculus
- face, larynx, pharynx have large representation on inferior portion of postcentral gyrus

74
Q

what is the unimodal association region of the parietal lobe

A

somatosensory association area (BA5,7)

75
Q

Somatosensory association area

A

posterior to postcentral gyrus
- integration of sensory input to form sensory perception

76
Q

what are the 3 multimodal association areas of the parietal lobe

A

parieto-temporo-occiputal region, supramarginal gyrus, angular gyrus

77
Q

parieto-temporo-occipital region

A

BA39,40
- Integration of multiple sensory inputs

78
Q

supramarginal gyrus

A
  • at caudal border of lateral fissure
    -receives auditory, visual, somatosensory info
  • involved in speech, reading, writing (participates in phonological processing)
79
Q

angular gyrus

A
  • at caudal border of superior temporal sulcus
  • receives auditory, visual, and somatosensory info
  • involved in speech, reading, writing (participates in semantic processing)
80
Q

what is the sulci of the temporal lobe

A

lateral sulcus

81
Q

what are the gyri of the temporal lobe

A

superior temporal (BA22)
heschl’s gyrus (BA41, 42)

82
Q

what is the primary region of the temporal lobe

A

primary auditory cortex (A1)

83
Q

primary auditory cortex (A1)

A

-heschl’s gyrus (transverse temporal gyrus) - BA 41, 42
- from upper surface of the superior temporal gyrus, the transverse temporal gyrus, or Heschlls gyrus, projects medially
- distinct tonotopic (low to high freq) organization has been identified in the primary auditory cortex (Heschl’s gyrus and insula)

84
Q

what is the unimodal association area in the temporal lobe

A

auditory association area BA22

85
Q

Auditory association area (BA22)

A
  • wernicke’s area
  • planum temporale - posterior portion of temporal operculum (from heschel’s G to the end of the lateral sulcus)
    posterior half of the superior temporal gyrus
  • important for language comp (receptive language processing) - applies meaning to what we hear
  • auditory word recognition
86
Q

2 sulci of the occipital lobe

A

parieto-occipital, calcarine sulcus

87
Q

3 gyri of the occipital lobe

A

cuneus gyrus, lingula gyrus, occipital gyri

88
Q

primary region of the occipital lobe

A

calcarine sulcus BA 17

89
Q

Calcarine sulcus

A

primary reception area for visual input
- visual image is projceted onto calcarine sulcus (left for right), upside down

90
Q

what is the unimodal association area for the occipital lobe

A

BA 18, 19, 7, 21, 20

91
Q

BA 18, 19, 7, 21, 20

A

Higher level processing of visual input
pathology in this region leads to cortical blindness, visual agnosia

92
Q

insula

A

hidden lobe of the cortex
- role in human emotion and behaviour (addiction, anxiety, depression)
- sensory processing
- motor planning and execution

93
Q

describe the insula’s role in sensory processing and integration

A
  • contains neurons that are responsive to somatic, visceral, visual, gustatory, and auditory stimulation
  • the seat of “subjective reality” - how you relate to what is going on in your body
  • includes vestibular cortex, gustatory cortex, visceral sensory cortex, auditory association cortex
94
Q

vestibular cortex

A

conscious awareness of sense of balance

95
Q

gustatory cortex

A

conscious awareness of taste stimuli

96
Q

visceral sensory cortex

A

conscious awareness of sensory input from thoracic and abdominal organs

97
Q

auditory association cortex

A

posterior region, closest to Heschl’s gyrus

98
Q

describe the insula’s role in motor programming

A
  • swallowing = coordinates motor activity of oral musculature w taste and autonomic functions
  • speech = coordination of articulatory seq, translation of phonologic code into previously learned kinematic plans, damage may lead to apraxia of speech (AOS)
99
Q

describe the insula’s role in viseceral motor activities (ANS)

A

involved in GI motility, cardiovascular responses, respiration, salivatory responses (ex. damage can lead to cardiac abnormalities including arrhythmias and even sudden cardiac death)

100
Q

within the telencephalon (internal white matter), what 3 types of fibre tracts travel beneath the cortex

A

association tracts, commissural tracts, projection tracts

101
Q

what is the finger trick for the 3 internal white matter fibre tracts

A

association = pointer fingers
commissural = middle fingers
projection = thumbs

102
Q

association fibres

A

connect cortical areas w/i a hemisphere

103
Q

2 types of association fibres

A

short fibres and long fibres

104
Q

short association fibres

A
  • connect primary areas to unimodal association areas w/i a cortical lobe (take info from primary to association)
  • lesions to primary sensorimotor areas can result in degeneration in the association areas due to lack of info sharing
105
Q

long association fibres

A

connect more distant cortical regions across cortical lobes

106
Q

arcuate fasciculus

A

extends from wernicke’s area to broca’s area (language comprehension/langauge programming to motor programming) - hears something which goes to temporal lobe, now need to respond which sends it to broca’s area so that we know what to say

107
Q

commissural fibres

A
  • corpus callosum and 2 smaller pathways (anterior commissure and posterior commisure) connect the 2 cortical hemispheres
  • other non-cortical structures are also connected by commissural fibres (ex. thalamus and hippocampus)
108
Q

corpus callosum

A
  • commissural fibres
  • connection bw the hemispheres (takes info from same place on one side to same place on other side)
  • comprised of at least 200 mill fibres
  • ## fibres of corpus callosum are primarily homolateral - travel bw homologous loci in the 2 hemispheres (ex. auditory cortex in primates has mostly homolateral projections; the fibres are often referred to as the transcollasal auditory pathway)
109
Q

projection fibres

A

connect regions of cerebral cortex to lower parts of the CNs (ex. thalamus, brainstem, spinal cord)

110
Q

all projection fibres entering/exiting the cortex come together as the?

A

internal capsule - travelling bw the nuclei of the basal ganglia (both afferent and efferent fibres)

111
Q

the pathway of sensory projection fibres for audition is

A

medial geniculate body (thalamus) sends projection fibres to Heschl’s gyrus (A1)

112
Q

the pathway of sensory projection fibres for touch/pressure is

A

from thalamus to S1 in postcentral gyrus

113
Q

the pathway of motor projection fibres is

A

cortical motor fibres from M1 descend the pyramidal tract

114
Q

Within the telencephalon’s internal gray matter (deep gray matter), what are the 3 subcortical regions?

A

Basal ganglia, amygdala, hippocampal formation

115
Q

what are the 3 structures the basal ganglia is comprised of

A

caudate nucleus, putamen, globus pallidus

116
Q

globus pallidus

A

w/i basal ganglia - nuclei participate in control of body posture and muscle tone, and planning/initiating movements

117
Q

what are the 2 functional units of the basal ganglia

A

substantia nigra and subthalamic nucleus

118
Q

what do the substania nigra and subthalamic nucleus do?

A
  • both areas function like the basal ganglia (v connected) and act like the BG
  • Substantia N - axons from SN in midbrain terminate in caudate N and putamen
  • Subthalamic N - axons from subthalamic N innterconnect w globus pallidus
119
Q

how is parkinsons related to the basal ganglia

A

motor disease of the BG - difficulty planning/initiating/terminating movement - but often BG has no pathology - instead pathology in substantia nigra - SN causes BG to dysfunction

120
Q

how does the basal ganglia communicate w the cortex

A

communicates extensively w the cortex: receives input from many cortical regions, and all output is sent back to motor cortex, via the thalamus

121
Q

Basal ganglia’s major functions

A

assist in regulating initiation and termination of movements, regulating intensity - also controls subconscious contractions of muscles (ex. arm swinging w walking) - also involved in initiating and terminating cog processes (attention, memory, planning) …. may work w limbic sys to regulate emotional behaviour (OCD)

122
Q

limbic system

A

functional brain system comprised of a group of structures on the medial aspect of the cerebral hemispheres - connects to cortex so that we can regulate our emotions (especially connected to frontal cortex)
“emotional brain”

123
Q

what structures does the limbic sys include

A

cingulate gyrus, parahippocampal gyrus, amygdala, hippocampal formation

124
Q

amygdala

A

a part of the limbic system, involved in processing and responding to fear, forms and retrieves memories based on emotional impact

125
Q

hippocampal formation aka hippocampus

A

encodes, consolidates, retrieves memories of facts and events