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Clinical Neuroscience > Arousal, Sleep + Consciousness > Flashcards

Arousal, Sleep + Consciousness Flashcards

1
Q

Define arousal

A

Emotional state associated with a goal or avoiding something noxious/toxic usually goal orientated

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2
Q

Define sleep

A

The readily reversible sate of reduced responsiveness to + interaction with the environment

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3
Q

Define consciousness

A

Difficult to define mainly to do with awareness of internal + external world

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4
Q

What are the two main components needed for consciousness?

A

Functioning cerebral cortex
Reticular formation

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5
Q

What is the reticular formation?

A

Diffuse network of specialised interneurones running the entire length of the brainstem

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6
Q

How is the reticular formation divided?

A

Median, medial + lateral columns

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7
Q

How is the cortex and reticular formation connected?

A

Reciprocal excitatory projections
Forming positive feedback loop

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8
Q

What are the 2 components required for consciousness + their function in this

A
  • Cerebral cortex: site where conscious thoughts arise**
  • Reticular formation: circulatory that keeps cortex awake
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9
Q

Describe the outputs of the reticular formation to the cortex

A

Reticular formation sends cholinergic (excitatory) projections to 3 major relay nuclei:
- basal forebrain nuceli send excitatory cholinergic fibres to cortex
- hypothalamus sends excitatory histaminergic fibres to cortex
- thalamus send excitatory glutamatergic fibres to cortex

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10
Q

What fibres connect the basal forebrain nuclei to cortex?

A

Excitatory cholinergic fibres

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11
Q

What fibres connect the hypothalamis to cortex?

A

Excitatory histaminergic fibres

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12
Q

What fibres connect the thalamus to cortex?

A

Excitatory glutamatergic fibres

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13
Q

What is used to assess consciousness clinically?

A

GCS
Glasgow coma scale

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14
Q

What are the 3 components of GCS?

A

Eye opening
Motor response
Verbal response

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15
Q

Eye opening GCS scoring + what it suggests

A
  • 4: spontaneous eye opening | normal cortical + brainstem function
  • 3: response to speech | slightly reduced cortical function w functional brainstem
  • 2 response to pain | impaired cortical function but brainstem preserved
  • 1: no response | severe damage to brainstem +/- cortex
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16
Q

Motor response GCS scoring
What does it suggest?

A
  • 6: obeys commands | normal function w connections between brainstem + auditory system
  • 5: localises stimuli | diminished higher cortical function but in tact connections between sensory + motor cortex
  • 4: withdraws to pain |still physiological response to stimuli
  • 3: flexor response to pain |lesion above red nuclei
  • 2: extensor response to pain | lesion below red nuclei
  • 1: no response to pain | severe damage to brainstem +/- cortex
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17
Q

Verbal response GCS scoring
What does it suggest?

A
  • 5: oriented in time/place | normal cortical function
  • 4: confused conversation | diminished higher cortical function but language centres in tact
  • 3: inappropriate words |language centre damaged
  • 2: incomprehensible sounds | cortical damage with brainstem mediated groans
  • 1: no response: severe damage to brainstem +/- cortex
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18
Q

What is GCS score range?

A

3-15

19
Q

What does an electroencephalogram measure?

A

Synchronous neuronal activity
Larger the amplitude - more synchronous activity

20
Q

What are the suspected functions of sleep?

A

Energy conservation
Memory consolidation
Clearance of extracellular debris
Resetting of CNS

21
Q

Describe the resolution of EEG

A

Good temporal resolution
Poor spatial resolution

22
Q

What do results of EEG represent?

A
  • high frequency + low amplitude: alertness + waking or dreaming stage of sleep (REM)
  • low frequency + high amplitude: non dreaming sleep (non REM), drugged or coma
23
Q

Types of sleep

A

REM
Non REM

24
Q

Length of cycles in sleep + how many each night?

A

90 mins
~ 6 cycles

25
Q

Describe Non REM sleep

A
  • deactivation of reticular activating system due to thalamus inhibition
  • split into 4 stages
  • reduced muscle tone but not paralysed
  • EEG shoes high voltage + low frequency
26
Q

Describe REM sleep

A
  • EEG similar to beta waves
  • dreaming occurs in stage > EEG similar to conscious patient (low voltage + high frequency)
  • mediated by pons
  • muscle paralysis + Antonia
  • eye movements + cranial nerve function + autonomic effects preserved
27
Q

List three sleep disorders

A

Insomnia
Narcolepsy
Sleep apnoea

28
Q

What is insomnia?
What is it due to??

A

Inability to sleep
Due to anxiety or depression or another mental illness

29
Q

What is narcolepsy?

A

Dysregulation of circadian rhythm
Randomly + uncontrollably fall asleep

30
Q

What is sleep apnoea?
Who is it common in?

A
  • Temporary occlusion of airways during sleep resulting in intermittent sleep
  • Often in obese people due to excess neck fat > ompression of airways
31
Q

What does sleep apnoea cause?

A

Excessive daytime sleepiness

32
Q

What is locked in syndrome due to?

A

Occulsion of basilar or pontine arteries

33
Q

What is locked in syndrome?

A

All somatic motor function lost expect eye movement

34
Q

What is preserved in REM sleep?

A
  • eye movements
  • cranial nerve function
  • autonomic effects e..g penile erection and loss of thermoregulation
35
Q

Compare EEG in REM + non REM sleep

A
  • REM: high frequency + low voltage
  • non REM: high voltage + low frequency
36
Q

What are the stages of sleep + their EEG results?

A
  • awake with eyes open: beta waves
  • awake with eyes closed: alpha waves
  • stage 1: background of alpha + interspersed theta waves
  • stage 2/3: background of theta + interspersed sleep spindles + K complexes
  • stage 4: delta waves
  • REM sleep: similar to B waves - high frequency + low voltage
37
Q

What are sleep spindles?
What stage of sleep are they seen in?

A

High frequency bursts arising from thalamus
In stage 2/3

38
Q

What do K complexes represent?
What stage of sleep are they seen in?

A

The emergence of the intrinsic rate of the cortex before deepest stage of sleep
In Stage 2/3

39
Q

Name some conditions of disordered/absent consciousness

A

Coma
Brain dead
Persistent vegetative state
Narcolepsy

40
Q

What structure prevents sensory information being transmitted to cortex during sleep?

A

Thalamus

41
Q

Classes of medication which could cause drowsiness

A

Anticholinergics
Anti histamines
Anti depressants
Anti psychotics
Anti emetics

42
Q

Ways to reduce sensory input to brain when trying to fall asleep

A

Comfy clothes
Dark room
Good temperature room
Reduced noise e.g. ear plugs

43
Q

Explain the control of consciousness in the brain

A
  • controlled by the reticular formation
  • sends projections to thalamus, hypothalamus + basal forebrain nuclei
  • this forms activating systems
  • these 3 areas send excitatory projections to the cortex > stimulates cortex to stay awake
    .
  • basal forebrain nuclei - cholinergic B-C
  • hypothalamus - histaminergic H-H
  • thalamus - glutaminergic G+T

Clinical Neuroscience (20 decks)

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