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Neuro Block 8 > Thalamus And Hypothalamus > Flashcards

Thalamus And Hypothalamus Flashcards

1
Q

Where is the 3rd ventricle relative to the thalamus (diencephalon)

A

Medial to it

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2
Q

Where does the diencephalon run along

A

3rd ventricle

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3
Q

Thalamus and hypothalamus are deep (lateral) to

A

3rd ventricle wall

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4
Q

What is the thalamus superior to

A

Hypothalamus and midbrain

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5
Q

Hypothalamus is anterior to

A

Midbrain

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6
Q

Anterior border of diencephalon is marked by

A

The crossing of anterior commissure and optic chiasm

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7
Q

What runs right between the thalamus

A

3rd ventricle

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8
Q

What is the thalamus

A

A bunch of nuclei

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9
Q

Where are the LGN and MGN

A

Thalamus

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10
Q

What sits underneath the thalamus

A

LGN and MGN

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11
Q

What sits int he back near the bottom of the thalamus,us

A

Pineal body

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12
Q

Thin gray zone separating lateral vs anterior vs medial groups of nuclei on the thalamus

A

Intralaminar zone

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13
Q

Contains intralaminar nuclei, part of reticular activating system

A

Intralaminar zone

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14
Q

Midline nuclei

A

Single (un paired nuclei)

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15
Q

Means pillow. Posterior postion, related to visual system

A

Pulvinar

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16
Q

MD nucleus

A
  • olfactory and emotional information

- amygdala, olfactory cortex, basal ganglia

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17
Q

Anterior nucleus of thalamus

A
  • from hypothalamus talks to cortex and pays attention to stressful events
  • mammillothalamic tract, fornix
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18
Q

VA/VL nucleus of thalamus

A

Substantia nigra pars reticulata, GPi

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19
Q

VL nucleus of thalamus

A

Medial leminscus, spinothalamic tracts

SOMATOSENSORY FOR BODY

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20
Q

VPM nucleus of thalamus

A

-trigeminal lemniscus, trigeminothalamic tract, gustatory inputs

SOMATOSENSORY FOR FACE

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21
Q

What are the two somatosensory nuclei of the thalamus

A

VPL and VPM

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22
Q

LGN

A

Visual, from optic tract

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23
Q

MGN

A

From inferior collilcus

-auditory

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24
Q

Where does the anterior thalamus project to

A

Cingulate gyrus

-respond to situations that are stressful or rewarding

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25
Q

Where does the MD nucleus project to?

A

Prefrontal cortex

-normal motivational state and learning about reward/stressful events

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26
Q

What are the two major systems that have a role in maintaining the conscious state

A
  • reticular activating system

- sensory, motor, anterior and dorsomedial nuclei

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27
Q

What is the most important system for maintaining the conscious state

A

Reticular activating system

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28
Q

Reticular activating system

A
  • involves the intralaminar nuclei

- project diffusely throughout cortex to maintain the conscious state and alertness

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29
Q

Disruption of the reticular activating system

A

Disruption at any level causes a loss of consciousness

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30
Q

Sensory, motor, anteiror and dorsomedial nuclei

A

Reciprocal connections with their cortical targets, creates a positive feedback loop that assists in maintaining alertness and the conscious state, but is less critical than the reticular activating system

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31
Q

What happens when the sensory, motor, anterior, and dorsomedial nuclei of the thalamus get disrupted

A

Just a reduced level of alertness

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32
Q

Anteiror nucleus and cognition

A

AN receives input from hypothalamus and projects to cingulate gyrus. Function not well understood, probably promotes working memory, or learning during stressful or rewarding moments

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33
Q

Mediodorsal nucleus and emotion

A

Receives input from amygdala and is part of the basal nuclei “motivational loop”. Possible role in regulating mood, motivation, and executive functions

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34
Q

What does the anterior nucleus have interactions with

A

Cingulate gyrus, indirect influence on working memory function

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35
Q

Proposed role for lesions in AN

A

Diencephalic amnesia

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36
Q

Infarct or alcoholism-associated degernation of AN

A

-thiamine deficiency
Korsakoff’s syndrome
-impaired info transfer from working memory to long term memory: AN projects to cingulate gyrus, which projects to hippocampus

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37
Q

Mediodorsal nucleus

A

Projections to prefrontal cortex support prefrontal functions, including working memory, intellectual functions, planning, behavioral regulation, and mood

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38
Q

Lesions to mediodorsal nucleus

A

Lead to disorientation in immediate environment or social situation, learning/memory impairment, possibly related to clinical depression (MDD)

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39
Q

Blood supply to diencephalon

A

Branches from circle of willis vessels penetrate DORSALLY into hypothalamus and continue to reach thalamus
-arterial branches also supply optic nerves, chiasm, tracts: could lead to VF defect if ischemia

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40
Q

What is the hypothalamus vulnerable to

A

Invading tumors

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41
Q

What are some arteries that supply the thalamus

A
  • posterior medial choroidal artery (from PCA)
  • thalamogeniculate artery (PCA)
  • paramedian branches (from PCA)
  • tuberothalamic branches (posteiror comm artery)
42
Q

Key arteries for thalamus

A

Branches of proximal PCA and posterior comm artery

43
Q

Does the thalamus have the same blood supply as the internal capsule and the basal ganglia

A

No. Can damage one of these areas and the other will remain intact

44
Q

Damage to left LGN

A

Right homonomyous hemianopsia

45
Q

Damage to MGN

A

Impaired binaural processing

46
Q

Damage to VPL and VPM

A

Right face and body deficit

47
Q

Damage to VPM

A

Spared. Fibers from each side ascend bilaterally with ALS

48
Q

Damage to VA.VL

A

Impairment in motor coordination and fine-tuning

No motor strength loss!

49
Q

Would you get motor strength loss if you damaged the left Va/VL?

A

Nope

50
Q

Venous drainage of the thalamus

A

Thalamostriate vein and the internal cerebral vei

51
Q

Venous accidents

A

Not likely in the thalamus

-elsewhere in larger vessels can result in back filling, increased ICP, and risk of hemorrhage

52
Q

What is the main venous drainage for the thalamus

A

Thalamostriate vein

-then to the internal cerebral vein-great cerebral vein-straight sinus-confluence of sinuses

53
Q

Anteiror boundaries of the hypothalamus

A

Lamina terminals

Preoptic area

54
Q

Ventral anatomical borders of the hypothalamus

A
  • optic chiasm
  • infundibulum
  • tuber cinereum
55
Q

Posteiror/caudal anatomical boundaries of the hypothalamus

A
  • midbrain

- mammillary bodies

56
Q

Major functions of the hypothalamus

A
  • endocrine regulation
  • reproductive behavior
  • thermoregulation
  • conscious state
  • feeding/appetite
  • circadian rhythm
  • autonomic NS regulation
57
Q

What are structures that sit below the hypothalamus

A

The pituitary gland sitting in the cella tursica that is attached by the infundibulum

58
Q

Major arterial supply to the hypthalamus

A

Branches from circle of willis vessels penetrate dorsally into hypothalamus

  • has very high density of arteries, arterioles, and capillaries. This, small risk and incidence of ischemic or hemorrhagic infarcts in hypothalamus
  • no defined vascular territories
59
Q

Hypothalamic regulation of the autonomic nervous system

A

Nuclei with descending projections directly to sympathetic or parasympathetic pre-ganglionic neurons or with indirect effects via reciprocal interactions with projections brainstem regions

60
Q

Anterior hypothalamic area and autonomic nervous system

A
  • promotes sweating (sympathetic)

- promotes GI function (parasympathetic)

61
Q

Autonomic function of paraventricular N (hypothalamic nuclei)

A

Can increase blood pressure and heart rate (symp)

62
Q

Autonomic nervous system function of dorsomedial N (hypothalamic nuclei)

A

Can increase blood pressure and heart rate (symp)

63
Q

Autonomic nervous system function of posterior hypothalamic nucleus/area

A

Vasoconstriction (symp)

64
Q

Where does heat dissipation occur

A

Anterior hypothalamic area

65
Q

Where does heat conservation occur

A

Posterior hypothalamic area/nucleus

66
Q

Heat dissipation in the anterior hypothalamic area

A
  • contains the rose story neurons (ambient hypothalamic temp)
  • cold activated and heat activated neurons
  • contributes to set point body temp, like thermostat
  • hyperthermic-sensitive neurons activate sweating, vasodilation in skin
  • pyrogens inhibit anterior H area
67
Q

What contributes to set point of body temperature like a thermostat

A

Anterior hypothalamic area

68
Q

Lesions to anterior hypothalamic area and heat regulation

A

Hyperthermia

69
Q

What do hyperthermic-sensitive neurons in the anteiror hypothalamic area do

A

Activate sweating, vasodilation in skin

70
Q

Pyrogens and anterior hypothalamic area

A

Inhibit it

  • prostaglandins
  • cytokines
  • infectious pathogen molecules
71
Q

Thermosensitive neurons in the anterior hypothalamic area are activated by what

A

Drop in body temperature

  • mediates vasoconstriction in skin, shivering, and stimulation of TRH
  • in infants, activates brown adipose tissue
72
Q

Lesions to the posteiror H area

A

Produce loss of thermoregulation due to impaired heat conservation and collateral damage to descending projections from anterior H area

73
Q

Histamine and hypothalamus

A

Promotes alertness/arousal

74
Q

Where is the histamine system located

A

In posterior H nucleus and tuberomammillary nucleus

75
Q

Targets of histamine system

A

Widespread projection targets include cerebral cortex and limbic system

76
Q

What is the mechanism of drowsy side effects of early anti-histamine

A

Histamine system having widespread projection targets including cerebral cortex and limbic system

77
Q

What does the hypocretin/orexin system promote

A

Wake state

78
Q

Orexin

A

Part of a system that promotes wake state and has a role in promoting feeding

79
Q

Where are the hypocretin/orexin neurons located

A

Diffuse population of neurons mostly located in lateral hypothalamic area

80
Q

What are the projection targets of the hypocretin/orexin system

A

Cerebral cortex, limbic system, brainstem sites

81
Q

Hypocretin/orexin deficiency

A

Narcolepsy

-sudden “sleep-attacks” no voluntary control, often begins with REM sleep

82
Q

Feeding and ventromedial nucleus

A

Feeding suppressive

83
Q

Lateral hypothalamic area (orexin neurons) and feeding

A

Feeding promoting

84
Q

Lateral hypothalamic area lesions and feeding

A

Reduce body weight (temporarily )

85
Q

What is the satiety center in the hypothalamus

A

VMN

86
Q

What is the appetite center in the hypothalamius

A

LHA

87
Q

What would VMN lesions disrupt

A
  • impair signaling of stomach dissension
  • impair signaling of adequate nutrients
  • impair insulin regulation
  • impair signals to brain from white adipose
  • impair stress-induced suppression of feeding
88
Q

Accurate nucleus of hypothalamus and feeding

A

Arcuate neurons detect nutrient in blood (glucose sensing, lipid sensing, amino acid sensing)

89
Q

Released in response to porting/fat ingested, limits meal size

A

CCK (cholecytokinin)

90
Q

Where is CCK released from

A

Arcuate nucleus

91
Q

What do arcuate and VMH together typically do to feeding

A

Inhibit

92
Q

What does LHA generally do

A

Promotes feeding

93
Q

What is LHA activated by

A

Glucocorticoids, reduced levels of satiety signal, release of “craving” signals

94
Q

Paraventricular N and feeding

A

Bidirectional effects on feeding

95
Q

Stress and feeding

A

Can have bidirectional effects on feeding

  • inhibitory mechanisms: stress-induced activation of brainstem norepi and serotonin systems with projections to feeding related nuclei act to suppress hunger/craving/eating
  • stress induced release of glucocorticoids (from HPA axis) can act in the hypothalamus and other rain trigger hunger/eating
96
Q

What nucleus regulates the circadian rhythm

A

Suprashiasmatic nucleus (SCN)

97
Q

When does pineal release melatonin

A

Dark, inhibited by light

98
Q

What does light to in pineal gland

A

Activates melanopsin ganglion cell neurons, which send excitatory projections to SCN via retina-hypothalamic tract

  • SCN sends excitatory projections to PVN (PVH), which projects to pre-ganglionic sympathetic neurons and activates them
  • postganglionic projections to pineal inhibits melatonin secretion
99
Q

Targets and rhythms of circadian rhythm

A

Multiple targets, multiple rhythms

100
Q

Experimental demonstration of 25 hour free running circadian rhythms in hamsters and humans and role of SCN

A
  • 24/7 constant light
  • activity beceoms 25 hour daily routine
  • SCN lesions, daily rhythm is totally chaotic
101
Q

Mammillary bodies role in memory function/deficits

A

Are indirectly connected to limbic structures that are critical for memory function

102
Q

Maxillary body and Korsakoff’s syndrome

A
  • damage due to thiamine deficiency (alcoholism or malnourishment)
  • short term and long term memory impairment
  • confabulation (making up memories)
  • shorter term memory function also impacts language comprehension and ability to communicate during convo
  • sometimes oculomotor deficit and ataxis (Wernicke-Korsakoff)

Neuro Block 8 (11 decks)

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