Reticular Formation and Consciousness Flashcards

1
Q

Where does the brainstem end

A

The thalamus

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2
Q

True or False:

The reticular formation continues into the thalamus a tiny bit

A

True

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3
Q

True or False:

The reticular formation consists of a net like arrangement of neurons

A

True

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4
Q

What is the net like arrangement of neurons within (3)

A
  1. Central core of the brainstem (tegmentum)
  2. Top of the spinal cord
  3. Non-specific thalamic matter
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5
Q

True or False:

Cells of the reticular formation are located in the brainstem tegmentum

A

True

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6
Q

True or False:
The reticular formation lies outside major nuclei and tracts though it is connected to a variety of areas by an immense number of polysynaptic pathways

A

True

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7
Q

True or False:

The reticular formation receives input from nearly all sensory systems

A

True

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8
Q

What is the only sensory system that the reticular formation does not receive info from

A

Dorsal column - Medial lemniscus

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9
Q

True or False:

Has efferent connections, either direct or indirect with all levels of the CNS

A

True

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10
Q

True or False:

The reticular formation affects motor, sensory, and autonomic functions as well as the responsiveness of the cortex

A

True

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11
Q

What does a mesencephalic transection leave an unresponsive animal with (3)

A
  1. Abnormal pupils
  2. A continuously awake state (hypersomnia)
  3. Spontaneous breathing
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12
Q

What does a spinal cord transection leave an alert animal with (3)

A
  1. Sleep wake cycles (though altered)
  2. Normal pupillary reactions
  3. Normal EEG
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13
Q

Is the cat alert or unresponsive with a mesencephalic transection

A

Unresponsive

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14
Q

Is the cat alert or unresponsive with a spinal cord transection

A

Alert

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15
Q

True or False:

The reticular formation is not a diffusely organized set of cells

A

True

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16
Q

True or False:

The reticular formation has numerous specific nuclei that each have a precise and organized projection pattern

A

True

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17
Q

True or False:

The reticular formation is actually not net like

A

True

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18
Q

What are the specific NT released from nuclei in the tegmentum (5)

A
  1. Acetylcholine
  2. Dopamine
  3. Norepinephrine
  4. Serotonin
  5. Histamine
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19
Q

True or False:

Several CN nuclei are buried deep in the reticular formation

A

True

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20
Q

Where do the RF efferent projections travel long and short distances to (3)

A
  1. Forebrain
  2. Spinal cord
  3. Cerebellum
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21
Q

Where do the RF efferent long distance projections originate in

A

The medial 2/3 of the RF

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22
Q

Where do the RF efferent short distance projections originate in

A

The lateral 1/3 of the RF

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23
Q

How are the RF dendritic branches oriented

A

Perpendicular to the axis of the brainstem

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24
Q

What do the RF dendritic branches do

A

Maximize communication

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25
Q

RF efferent projections of the pons and medulla consist of (2)

A
  1. Long descending neurons that synapse with other neurons that contain a long ascending axon
  2. Bifurcating neurons giving rise to both the ascending and descending branches
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26
Q

True or False:

RF efferent projections have collateral connections

A

True

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27
Q

What do the collateral connections provide

A

Additional integrating mechanism

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28
Q

What is the simplified functional and organizational scheme of the RF

A

Consists of a central core of nuclei found in the brainstem tegmentum that run through the entire length of the brainstem

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29
Q

What is the RF continuous with rostrally

A

Certain diencephalic nuclei

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30
Q

What is the RF continuous with caudally

A

Within the intermediate zone of the spinal cord

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31
Q

What is the rostral continuation of the RF responsible for

A

Consciousness

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32
Q

What is the caudal continuation of the RF responsible for

A

Unconsciousness

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33
Q

What is the intermediate zone of the thoracic and sacral levels

A

Where the fibers of the RF come down and synapse on the gray matter

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34
Q

The rostral portion of the RF is in what structures (3)

A
  1. Mesencephalon
  2. Upper pons
  3. Some diencephalic nuclei
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35
Q

What is the function of the rostral portion of the RF

A

Necessary for maintenance of an alert, conscious state in the forebrain

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36
Q

What is another name of the rostral portion of the RF

A

Ascending reticular activating system (ARAS or RAS)

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37
Q

The caudal portion of the RF is in what structures (2)

A
  1. Pons

2. Medulla

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38
Q

What is the function of the caudal portion of the RF

A

Work together with the cranial nerve nuclei and the spinal cord to carry out a variety of motor, reflex, and autonomic functions

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39
Q

True or False:

The caudal reticular formation modulates motor output

A

True

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40
Q

True or False:

The ascending system of the RF is the same as the RF consciousness system

A

True

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41
Q

What does the reticular formation consciousness system consist of

A

Cortical and subcortical networks of the brain that carry out the major functions of consciousness

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42
Q

What is the reticular formation consciousness system formed principally by (2)

A
  1. Medial and lateral frontoparietal association cortices

2. Arousal circuits in the upper brainstem and diencephalon

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43
Q

What do the subcortical arousal systems result from

A

Result from diffuse projection systems

44
Q

True or False:

The diffuse projections of the subcortical arousal system each emanate from a single region to innervate many structures

A

True

45
Q

Where do most of the subcortical arousal system projections in the brainstem that innervate the forebrain arise from

A

Upper brainstem

46
Q

Where do the subcortical arousal system projections of the brain, cerebellum, or spinal cord arise from

A

Lower pons or medulla

47
Q

True or False:
Some of the subcortical arousal system projections have their main source outside the brainstem in the hypothalamus or basal forebrain

A

True

48
Q

The content of consciousness is comprised of systems mediating what (4)

A
  1. Sensory
  2. Motor
  3. Memory
  4. Emotional functions
49
Q

What is the content of consciousness mediated by

A

Brain systems that provide the substrate (content) upon which the consciousness system acts

50
Q

What does the content of consciousness depend on

A

What gets up to the thalamus

51
Q

What is the level of consciousness regulated by

A

The consciousness system

52
Q

What are the 3 processes involved in the level of consciousness

A
  1. Alertness
  2. Attention
  3. Awareness
53
Q

True or False:

Consciousness is intentional integration of memory

A

True

54
Q

Alertness depends on what

A

The RF

55
Q

What circuits of the RF does alertness depend on (3)

A
  1. Rostral brainstem
  2. Diencephalic arousal circuits
  3. Cortex
56
Q

What circuits does attention use (4)

A
  1. Rostral brainstem
  2. Diencephalic arousal circuits
  3. Cortex
  4. Frontoparietal association cortices
57
Q

True or False:

Awareness is the least well understood of the levels of consciousness (alertness, attention, and awareness)

A

True

58
Q

What does awareness refer to

A

Our subjective and personal experiences

59
Q

What does awareness depend on

A

Our ability to combine various higher order forms of sensory, motor, emotional, and memory from wide regions of the brain into a unified summary of current mental activity which presumably can be remembered later

60
Q

True or False:

Working memory is part of awareness

A

True

61
Q

True or False:

Alertness is part of the ascending projection systems

A

True

62
Q

What do lesions of the rostral brainstem and reticular formation and medial diencephalon cause

A

Coma

63
Q

What can stimulation of the rostral brainstem and reticular formation and medial diencephalon lead to

A

Behavioral and electroencephalographic arousal fro deep anesthesia (brain thinks they are alert)

64
Q

True or False:

It is thought that anesthesia interferes with reticular formation Na+ channels

A

True

65
Q

What regions make up the reticular activating system (RAS) (3)

A
  1. Rostral brainstem
  2. Medial diencephalon
  3. Reticular formation
66
Q

True or False:
It was found that the critical systems of the reticular activating system are not all ascending and do not all originate from the reticular formation

A

True

67
Q

What does the RAS not all being ascending and not all originating from the RF cause

A

There to be multiple interconnected arousal systems acting in parallel to maintain consciousness

68
Q

Lesions to what regions can cause coma (3)

A
  1. Upper brainstem RF and related structures
  2. Dysfunction of extensive bilateral regions of cerebral cortex
  3. Bilateral lesions of the thalamus (particularly those involving the medial and intralaminar regions
69
Q

What are the related structures of the upper brainstem RF that can cause coma (2)

A
  1. Lower brainstem (pons and medulla)

2. Ventral midbrain or pons that spare the RF

70
Q

Does a lesion to the lower brainstem (pons and medulla) effect consciousness

A

Nope

71
Q

Does a lesion to the ventral midbrain or pons that spares the RF effect consciousness

A

Nope

72
Q

What happens with lesion to the ventral midbrain or pons that spares the RF

A

Locked in syndrome

73
Q

The upper brainstem neurons contain what NT (4)

A
  1. Norepinephrine
  2. Serotonin
  3. Dopamine
  4. Acetylcholine
74
Q

Where do the neurons of the upper brainstem containing NE, serotonin, and dopamine project (2)

A
  1. Cortical structures

2. Subcortical structures

75
Q

Where do the neurons of the upper brainstem and pontomesencephalic RF neurons that contain acetlycholine project (3)

A
  1. Thalamus
  2. Hypothalamus
  3. Basal forebrain
76
Q

The posterior hypothalamic neurons contain what NTs (2)

A
  1. Histamine

2. Orexin

77
Q

Where do the posterior hypothalmic neurons project (2)

A
  1. Cortical areas

2. Subcortical areas

78
Q

What are histamine and orexin involved in

A

Sleep

79
Q

The basal forebrain neurons contain what NTs (1)

A
  1. Acetylcholine
80
Q

Where do the basal forebrain neurons project (1)

A
  1. Cerebral cortex
81
Q

The neurons in the rostral thalamic intralaminar nuclei and other medial thalamic nuclei contain what NTs (1)

A
  1. Dopamine
82
Q

Where do the neurons in the rostral thalamic intralaminar nuclei and other medial thalamic nuclei project (1)

A
  1. Cerebral cortex
83
Q

Cholinergic projeciton systems release what

A

Acetylcholine

84
Q

What are the functions of the cholinergic projection systems (3)

A
  1. Arousal
  2. Selective attention
  3. Learning and memory
85
Q

Cholinergic inputs to the thalamus cause what

A

Arousal

86
Q

What do direct (mostly facilitory) inputs to cortex of the cholinergic projection system originate in

A

Forebrain

87
Q

What are the functions of the noradrenergic projection systems (5)

A
  1. Arousal
  2. Selective attention
  3. Sleep
  4. Autonomic functions (with hypothalamus and amygdala)
  5. Sensory processing (especially pain)
88
Q

True or False:

Pain will wake you up out of sleep but has no effect on coma

A

True

89
Q

True or False:

The ascending tract of the RF comes to life in dreams while the descending tract of the RF is paralyzed

A

True

90
Q

True or False:

Serotonergic projection systems have the most variations of its receptors

A

True

91
Q

True or False:

Serotonin is thought to have been around the longest

A

True

92
Q

What are the functions of the serotonergic projection systems (5)

A
  1. Arousal
  2. Selective attention
  3. Sleep
  4. Sensory processing
  5. Regulation of muscle tone and spinal reflexes
93
Q

What is the function of the dopaminergic projection systems in the mesostriatal neurons (nigrostriatal neurons)

A

Regulates direct and indirect pathways for movement

94
Q

What is the function of the dopaminergic projection systems in the mesolimbic neurons

A

Positive symptoms of schizophrenia

95
Q

What is the function of the dopaminergic projection systems in the mesocortical neurons

A

Cognitive deficits and hypokinesia in parkinson’s

96
Q

What are the functions of the histamine projection systems (4)

A
  1. Arousal
  2. Sleep
  3. Learning and memory
  4. Energy balance
97
Q

Where do the arousal circuits of the pontomesencephalic reticular formation travel through

A

The internal capsule

98
Q

Does a person in the brain death stage of impaired consciousness have purposeful responses to stimuli, Behavioral arousal, sleep-wake cycles, brainstem reflexes, and spinal cord reflexes

A

Purposeful responses to stimuli: No
Behavioral arousal, sleep-wake cycles: No
Brainstem reflexes: No
Spinal cord reflexes: Yes

99
Q

Does a person in the coma stage of impaired consciousness have purposeful responses to stimuli, Behavioral arousal, sleep-wake cycles, brainstem reflexes, and spinal cord reflexes

A

Purposeful responses to stimuli: No
Behavioral arousal, sleep-wake cycles: No
Brainstem reflexes: Yes
Spinal cord reflexes: Yes

100
Q

Does a person in the vegetative stage of impaired consciousness have purposeful responses to stimuli, Behavioral arousal, sleep-wake cycles, brainstem reflexes, and spinal cord reflexes

A

Purposeful responses to stimuli: No
Behavioral arousal, sleep-wake cycles: Yes
Brainstem reflexes: Yes
Spinal cord reflexes: Yes

101
Q

Does a person in the minimally conscious stage of impaired consciousness have purposeful responses to stimuli, Behavioral arousal, sleep-wake cycles, brainstem reflexes, and spinal cord reflexes

A

Purposeful responses to stimuli: Yes
Behavioral arousal, sleep-wake cycles: Yes
Brainstem reflexes: Yes
Spinal cord reflexes: Yes

102
Q

What part of the brain is responsible for purposeful response to stimuli (1)

A

Cerebral cortex

103
Q

What part of the brain is responsible for behavioral arousal, sleep-wake cycles (2)

A

Diencephalon and upper brainstem

104
Q

What part of the brain is responsible for brainstem reflexes (2)

A

Brainstem reflex and motor systems

105
Q

What part of the brain is responsible for Spinal reflexes (1)

A

Spinal cord circuits