EEG, Sleep (Motor Control 3)

Question 1

List the basic conscious states

Answer 1

Normal Consciousness
Delirium
Dementia
Confusion
Somnolence
Chronic Vegetative State

Question 2

List the basic unconscious states

Answer 2

Stupor
Coma
(Delirium)
(Dementia)
Coma

Question 3

What is the main scale for assessing consciousness?

Answer 3

Glasgow Coma Scale - GCS

Question 4

What is an EEG?

Answer 4

Electroencephalogram - important tool for assessing the sate of consciousness

Question 5

What are the two ways in which activity can be analysed via EEG?

Answer 5

Amplitude - the bigger the wave the more of the activity is synchronised
Frequency - the higher the frequency, the faster the rate of fluctuations in the cortical cells

Question 6

Describe the amplitude and frequency on the EEG when the subject is awake

Answer 6

Low amplitude

High frequency

Question 7

Summarise the EEG findings in the alert brain

Answer 7

EEG amplitude is low because the brain is busy doing many different things rapidly, and EEG is therefore not synchronised, but the frequency is high

Question 8

What are the two basic forms of sleep?

Answer 8

REM sleep/ D-sleep(desynchronised)/ paradoxical sleep

Slow wave/ non-REM/ S-sleep(synchronised)

Question 9

Describe the change in the EEG during S-wave/slow wave/non-REM sleep

Answer 9

There is a gradual increase in amplitude as the activity of more and more cells become synchronised and the frequency is low

Question 10

How many stages of sleep are there?

Answer 10

Four

Question 11

Does the sympathetic or parasympathetic system exert dominance during S-wave sleep?

Answer 11

Parasympathetic e.g. decreasing heart rate

Question 12

Why is REM sleep referred to as paradoxical sleep?

Answer 12

Because REM sleep produces EEG results that are very similar to the awake state, and yet it is very difficult to rouse someone from REM sleep, harder even than from stage 4 S-wave sleep

Question 13

What are the four physiological signs of REM sleep?

Answer 13

1. Profound inhibition of the body muscles as if the motor system has been switched off
2. With the exception of the eye muscles which demonstrate bursts of activity
3. This is the hardest sleep stage of all t rouse someone from, even though the EEG characteristics are the closest to those of an alert person
4. Unlike all stages of s-wave sleep, the sympathetic system exerts dominance, for example there is an increase in BP and HR, cerebral BF and increases brain temperature - i.e. the brain is very active whilst in REM sleep

Question 14

What percentage of people report that they were dreaming if awakened from REM sleep?

Answer 14

> 90%

Question 15

What is the important feature of S-sleep for health?

Answer 15

During stages three and four of S-wave there is up to a 20x increase in growth hormone production, making these stages of sleep crucial for restoration and repair

Question 16

What is the relationship between dementia patients and REM sleep?

Answer 16

Dementia patients to do not experience any REM sleep

Question 17

Give some important sleep disorders

Answer 17

Insomnia
Nightmares
Night Terrors
Somnambulism (sleep-walking)
Narcolepsy

Question 18

Summarise insomnia

Answer 18

Occurs in around one third of adults. Important to distinguish between temporary and chronic insomnia

Question 19

How should insomnia be managed?

Answer 19

Often due to underlying feelings of anxiety or depression which should be tackled rather than the subjective symptoms of insomnia. Sleeping drugs such as barbiturates may be used but can have severe long term consequences

Question 20

Describe the short term affects of barbiturate use in a patient with insomnia

Answer 20

Can be highly effective in the short term, greatly reducing the number of awakenings but preserving much of the original REM sleep

Question 21

Describe the long term effects of barbiturate use in a patient with insomnia

Answer 21

Over time the body with develop resistance, requiring dose increases. Over tie the number of awakenings is likely to return to original levels and often increase. The REM sleep is usually completely disrupted and features for very short amounts of time, if at all. The patient will likely no longer be able to enter stage 3 or 4 S-wave sleep, producing a severe deficit, as the patient is not receiving the restorative and regenerative benefits of the stage 3 and 4 sleep

Question 22

What is the consequence in terms of REM sleep if a long term barbiturates user stops using the drug?

Answer 22

There is a significant attempt by the body to catch up on the lost REM sleep, coupled with a big increase it frequency and intensity of dreams and nightmares

Question 23

What is the consequence in terms of stages 3 and 4 S-wave sleep if a long term barbiturate user stops using the drug?

Answer 23

The levels of stage 3 and 4 sleep will revert back to normal level, but gradually, not displaying any rebound or overshoot features

Question 24

Describe the manifestation of nightmares

Answer 24

They have a strong visual component and are seen during REM sleep when PGO (pontine-geniculo-occipital) spikes (APs) can be recorded

Question 25

What is the likely function of the shut off of the motor system during dreams/nightmares? Describe the scenario where this shutoff does not occur

Answer 25

To prevent the subject from acting upon them

In REM behaviour disorder the motor shut off does not occur and can result in serious accidents and even murder

Question 26

Describe night terrors

Answer 26

They are associated with intense feeling of fear. They are a non-REM phenomenon. They are common in PTSD

Question 27

Describe somnambulism

Answer 27

Sleep-walking occurs exclusively in non-REM sleep, mainly in stage 4
As stage 4 sleep declines with age, it affects children predominantly, especially boys

Question 28

Describe generally, narcolepsy

Answer 28

The irresistible urge to sleep, lasting 5-30 minutes, usually during the day and at behaviourally inappropriate times. May be precipitated by feelings of string emotion eg during laughter or sex. Sufferers often enter directly into REM sleep

Question 29

Describe the effects of narcolepsy on the body

Answer 29

Sufferers are usually cataleptic whilst asleep i.e.. complete loss of muscle tone, but remain conscious. This makes it very dangerous due to accident risk

Question 30

Outline orexin and its relationship with narcolepsy

Answer 30

A hypothalamic neurotransmitter, orexin/hypocretin, stimulates wakefulness and demonstrates cyclic levels in the blood, with a decrease at night. Post-mortem brains of patients with narcolepsy have been shown to have around a 90% loss of orexin producing neurones - making orexin a possible treatment