8. Consciousness, Unconsciousness, Sleep, EEG

Question 1

What is consciousness?

Answer 1

Self-awareness, perception, ability to respond to stimuli and act with judgement

Question 2

What is sleep?

Answer 2

A state of altered consciousness

Person can be aroused by stimuli

Question 3

Which cycle controls when we sleep?

Answer 3

Circadian rhythm

Question 4

What is a coma?

Answer 4

Inability to sense or respond to stimuli

Loss of sleep/wake cycle

Question 5

What is the scale used to measure a coma?

Answer 5

Glasgow scale

Question 6

What categories are used in the Glasgow scale?

Answer 6

Eye opening
Verbal response
Motor response

Question 7

What are the ranges for severe to mild coma on the glasgow scale?

Answer 7

<8 severe
9-12 moderate
>13 mild

Question 8

What are causes of comas?

Answer 8

Intoxication
Acute neurological injury
Metabolic disorders
CNS infection
Stroke
Hypoxia

Question 9

How long can a coma last before the patient enters a vegetative state or dies?

Answer 9

5 weeks

Question 10

What is a vegetative state?

Answer 10

Unconsciousness in patients with severe brain injury
Have a certain degree of wakefulness (may be able to track objects with eyes)
Lack awareness and cognitive function

Question 11

What is brain death?

Answer 11

Irreversible coma
Loss of pain response and cranial nerve reflexes (fixed pupils, no blink reflex)
Loss of spontaneous respiration

Question 12

How long does an infradian rhythm last?

Answer 12

> 1 day

Question 13

How long does an ultradian rhythm last?

Answer 13

<1 day, > 1 hour

Question 14

Where is melatonin secreted from?

Answer 14

Pineal gland

Question 15

What stimulates the pineal gland?

Answer 15

SCN

Question 16

What are the functions of melatonin?

Answer 16

Induce sleep at night time

Help adjust to seasons and other time zones

Question 17

What sort of brain waves are characteristic of NREM sleep?

Answer 17

Slow

Question 18

What happens to HR, BP and temperature during NREM sleep?

Answer 18

Decrease: autonomic instability

Question 19

How long are REM cycles?

Answer 19

90 mins

Question 20

How many times do REM cycles occur during the night?

Answer 20

5-6

Question 21

What are the three parts of a polysomnography?

Answer 21

Electroencephalogram
Electroculograph
Electromyogram

Question 22

What is tracked by an EEG?

Answer 22

Changes in frequency, amplitude and synchronisation of brain waves

Question 23

What is tracked by an EOG?

Answer 23

Eye movements

Question 24

What is tracked by an EMG?

Answer 24

Muscle tension in face and leg

Question 25

What are the uses of an EEG?

Answer 25

Sleep Seizures Altered consciousness

Question 26

What rhythm is present when awake with eyes open?

Answer 26

β rhythm

Question 27

What rhythm is present when awake with eyes closed?

Answer 27

α rhythm

Question 28

What are the EEG, EOG and EMG results during NREM 1?

Answer 28

Theta waves (high amplitude, low frequency) Slow, rolling eye movements Slow muscle activity

Question 29

What are the EEG, EOG and EMG results during NREM 2?

Answer 29

Slow waves but occasionally rapid spindles/k complexes Eye movements stop Spontaneous muscle tone and relaxation

Question 30

What are the EEG findings during NREM 3?

Answer 30

Slow delta waves (also stage 4) | Interrupted by smaller, faster waves

Question 31

What are the EEG, EOG and EMG results during REM?

Answer 31

Fast, small amplitude brain waves Rapid eye movements Flaccidity

Question 32

What are the benefits of sleep?

Answer 32

``` Improves cognitive ability Solidify memory Increase decision making skills 'Eraser' theory Lack of sleep: increase HR, BP and obesity risk GH secreted during REM Increase immunity ```

Question 33

What controls NREM/REM cycles?

Answer 33

Reticular activating system

Question 34

What 2 ascending systems of reticular formation contribute to the RAS?

Answer 34

Neurons with ACh | Neurons with NA, serotonin, histamine

Question 35

What happens to neuronal activity during NREM?

Answer 35

Both cholinergic and monoaminergic pathways slow down

Question 36

What happens to neuronal activity during REM?

Answer 36

Cholinergic neurons fire rapidly | Monoaminergic neurons sop firing

Question 37

What controls the sleep/wake cycle?

Answer 37

Suprachiasmatic nucleus in the hypothalamus

Question 38

What does the SCN receive input from?

Answer 38

Retina

Question 39

What does the SCN provide signals to?

Answer 39

Pre-optic nucleus | Orexin neurons