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CNS > Lecture 11 - Brainstem, Arousal, Sleep And Consciousness > Flashcards

Lecture 11 - Brainstem, Arousal, Sleep And Consciousness Flashcards

1
Q

What is the Definiton of arousal?

A

Emotional state associated within a goal or avoiding something noxious or toxic

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2
Q

What is the definition of sleep?

A

The readily reversible state of reduced responsiveness to and interaction with theee environment

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3
Q

What is the definition of consciousness/

A

Hard to define

It’s related to the awareness of external environment and internal states

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4
Q

What are the 2 main components required for consciousness?

A

Functioning cerebral cortex
Functioning reticualr formation

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5
Q

What is the reticular formation/where is it found?

A

Diffuse network of interneurones running entire length of brainstem continous with white matter tracts from teh spinal cord and diencephalon

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6
Q

What are the 3 columns of the reticular formation?

A

Median
Medial
Lateral

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7
Q

What is the function of the median column of the reticular formation?

A

Arousal
Emotion

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8
Q

What is the function of the medial column of the reticular formation?

A

Somatosensory input processing

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9
Q

What is the function of the lateral column of the reticular formation?

A

Cranial nerve activity
Micturition

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10
Q

What are the 2 main inputs to the reticular formation?

A

Cortex
Sensory system

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11
Q

What is the overall role of the reticular formation?

A

Keeps the cortex awake/functioning (reticular activating system does this)

Integrate, relay and coordinate vital life functions and protective reflexes

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12
Q

What are the 3 main cortical regions which the reticular formation sends impulses to?

A

Thalamus
Hypothalamus
Basal forebrain nuclei

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13
Q

What neurotransmitter travels along the axons which are sent from the reticular formation to the thalamus?

A

Glutamate

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14
Q

What neurotransmitter travels along the axons which are sent from the reticular formation to the Hypothalmus?

A

Histamine (H hypothalamus H Histamine)

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15
Q

What neurotransmitter travels along the axons which are sent from the reticular formation to the basal forebrain nuclei?

A

Acetylcholine (ACh)

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16
Q

What type of feedback loop occur between the cortex and reticular formation when there’s a binary outcome (sleep or awake e.g)?

A

Postive feedback

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17
Q

How does the reticular activating system maintain wakefulness?

A

Reticualr activating system receives excitatory input from cortex, projects it’s own excitatory input back to cortex forming + feedback loop

Info sent to cortex amintaingni arousal and consciousness and blocking pathways promoting sleep

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18
Q

What nuclei of the reticular formation send the projections to the hypothalamus, thalamus and basal forebrain nuclei?

A

Median raphe

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19
Q

What are the 2 ways by which we can assess/measure cortical function?

A

Electroencephalogram (EEG)

Glasgow Coma Scale (GCS)

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20
Q

What is the Glasgow Coma Scale?

A

Clinical assesment of consciousness used to measure level of cerebral activity

Useful to localise lesion to cerebral cortex or brain stem

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21
Q

What 3 responses does the Glasgow Coma Scale (GCS) measure?

A

EMV

Eye repsonse
Motor response
Verbal response

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22
Q

What is better, a high GCS score or lower GCS score?

A

Higher GCS score

Indicates higher level of CNS function and less CNS dameage

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23
Q

What is the GCS scored out of?

A

15

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24
Q

What is the significance of a patient spontaneously opening their eyes? (GCS)

A

Cortical function is fine

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25
Q

What is the significance of a patient only opening their eyes when you tell them to? (GCS)

A

Slightly diminished cortical function but still functioning brainstem

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26
Q

What is the significance of a patient only opening their eyes when receiving pain stimulus? (GCS)

A

Impaired cortical function
Brainstem preserved since reflex functional

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27
Q

What is the significance of a patient not opening their eyes? (GCS)

A

Severe damage too brainstem (maybe also cortex)

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28
Q

What is the significance of a patient being able to obey commands for the motor repsonse part of GCS?

A

Normal function

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29
Q

What is the significance of a patient being able to localise to stimuli after a painful stimulus for the motor repsonse part of GCS?

A

Diminished higher cortical function but connections from sensory and motor cortex fine

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30
Q

What is the significance of a patient withdrawing to pain for the motor repsonse part of GCS?

A

Still a physiological reflex repsonse to stimuli so brainstem is fine

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31
Q

What is the significance of a patient having a flexor response to pain for the motor repsonse part of GCS?

A

Lesion above the red nuclei

32
Q

What is the significance of a patient having a extensor response to pain for the motor repsonse part of GCS?

A

Deep cortical lesion below the red nuclei

33
Q

What is the significance of a patient not having a response to pain for the motor repsonse part of GCS?

A

Severe damage to Brain stem and or cortex

34
Q

What is the significance of a patient having a correct verbal response to a question for the GCS score?

A

Normal cortical function

35
Q

What is the significance of a patient having a confused verbal response to a question for the GCS score?

E.g giving the wrong day of the week

A

Diminished higher cortical function

36
Q

What is the significance of a patient having an inappropriate verbal response to a question for the GCS score?

E.g saying sandwich when asked the day of the week

A

Language centres have been damaged (cortical function impaired)

37
Q

What is the significance of a patient having a non worded response like groaning or moaning response to a question for the GCS score?

A

Significant cortical damage where the brainstem is taking over

38
Q

What is the significance of a patient having no verbal response to a question for the GCS score?

A

Severe damage to brainstem and or cortex

39
Q

What is an electroencephalogram?

A

Measure electrical activity of the cerebral cortex from the scalp

40
Q

What does an electroencephalogram measure?

A

Measures how synchronous neuronal activity is

41
Q

When are the brains neurones most synchronous?

A

Non dreaming sleep
Drugged or coma

Essentially when there’s very little stimuli

42
Q

When are the Brains neurones least synchronous?

A

When highly alert, waking or dreaming stage of sleep (REM)

43
Q

How is highly synchronous neuronal/cortical activity represented on an electroencephalogram?

A

High amplitude and low frequency = synchronous

44
Q

How is non synchronised neuronal/cortical activity represented on an electroencephalogram?

A

Low amplitude and High frequency

45
Q

How is non synchronised neuronal/cortical activity represented on an electroencephalogram?

A

Low amplitude and High frequency

46
Q

How does sleep occur?

A

Reticular activating system gets deactivated by the THALAMUS
So cortical activity is reduced so sensory input is reduced
Neuronal activity synchronises

47
Q

Why do we need sleep?

A

Not completely understood:

Rest and recover?
Conservation of energy?
Protection?
Memory?
Clearance of metabolites?

48
Q

What system removes toxic metabolites from the brain?

A

Glymphatic system

49
Q

Why is the glymphatic system important?

A

Removes harmful proteins

Most active at night

Lack of sleep can lead to Alzheimer’s due to toxic protein build up

50
Q

What are the 2 types of sleep?

A

REM sleep
Non REM sleep

51
Q

What are the 2 types of sleep?

A

REM sleep
Non REM sleep

52
Q

How long does each REM - Non-REM sleep cycle last?

A

Both together is about 90mins

53
Q

How can you describe the muscle tone in Non-REM sleep?

A

Reduced muscel tone but can still move
(why you can jerk in night)

54
Q

What type of activity are seen with the neurones in Non-REM sleep?

A

High voltage + Low frequency (synchronous)

55
Q

How many stages of Non-REM sleep are there?

A

4

56
Q

How can you describe the muscle tone in REM sleep?

A

Muscle paralysis and Atonia

57
Q

Which part of the brain controls REM sleep?

A

Pons

58
Q

What functions are preserved in REM sleep?

A

Eye movements and other cranial nerve function

Autonomics (Penile erection and loss of Thermoregulation)

59
Q

What is nocturnal bruxism?

What causes it?

A

Grinding of teeth in sleep

Facial nerve overly active in sleep causing teeth to grind

60
Q

What waves are seen when awake with eyes open?

A

Beta waves irregular 50Hz

61
Q

What waves are seen while awake with eyes closed?

A

Alpha waves - regular 10Hz

62
Q

What waves are seen in Stage 1 of sleep?

A

Alpha and Theta waves at 5Hz

63
Q

What waves are seen at stages 2+3 of sleep?

A

Theta, sleep spindles and k-complex

64
Q

What are sleep spindles??

A

High frequency bursts coming from the thalamus

65
Q

What are k complex’s?

A

Slow synchronous activity

The intrinsic rate of the cortex

66
Q

What waves are seen in stage 4 sleep?

A

Delta waves (regular 1Hz)

67
Q

Label the EEG on slide 15

A
68
Q

What is insomnia?

A

Inability to sleep

Normally due to anxiety, depression or other mental or physical illness

69
Q

What is narcolepsy?

A

Dysregulation of your circadian rhythm

70
Q

What is sleep apnoea?

A

Temporary occlusion of the airway during sleep resulting in intermittent sleep

71
Q

What is the defintion of brain death?

A

Damage to brainstem and cortex (flat EEG)

72
Q

What is the defintion of coma?

A

Widespread brainstem and cortical damage
Has disordered EEG patterns and no sleep wake cycle

73
Q

What is the defintion of persistent vegetative state?

A

Cortical damage, the brainstem is fine but you have disordered EEG pattern, some eye movements and repsonse to stimuli

74
Q

What is locked in syndrome/what causes it?

A

Occlusion of the basilar/pontine arteries leads to loss of function of the corticospinal tract

Person cant move but can move their eyes and understand everything

75
Q

Why can a patient with locked in syndrome still move their eyes?

A

The edinger Westphal nucelus in the midbrain is unaffected

CNS (21 decks)

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