EEG, Sleep (Motor Control 3) Flashcards
List the basic conscious states
Normal Consciousness Delirium Dementia Confusion Somnolence Chronic Vegetative State
List the basic unconscious states
Stupor Coma (Delirium) (Dementia) Coma
What is the main scale for assessing consciousness?
Glasgow Coma Scale - GCS
What is an EEG?
Electroencephalogram - important tool for assessing the sate of consciousness
What are the two ways in which activity can be analysed via EEG?
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
Describe the amplitude and frequency on the EEG when the subject is awake
Low amplitude
High frequency
Summarise the EEG findings in the alert brain
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
What are the two basic forms of sleep?
REM sleep/ D-sleep(desynchronised)/ paradoxical sleep
Slow wave/ non-REM/ S-sleep(synchronised)
Describe the change in the EEG during S-wave/slow wave/non-REM sleep
There is a gradual increase in amplitude as the activity of more and more cells become synchronised and the frequency is low
How many stages of sleep are there?
Four
Does the sympathetic or parasympathetic system exert dominance during S-wave sleep?
Parasympathetic e.g. decreasing heart rate
Why is REM sleep referred to as paradoxical sleep?
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
What are the four physiological signs of REM sleep?
- Profound inhibition of the body muscles as if the motor system has been switched off
- With the exception of the eye muscles which demonstrate bursts of activity
- 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
- 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
What percentage of people report that they were dreaming if awakened from REM sleep?
> 90%
What is the important feature of S-sleep for health?
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
What is the relationship between dementia patients and REM sleep?
Dementia patients to do not experience any REM sleep
Give some important sleep disorders
Insomnia Nightmares Night Terrors Somnambulism (sleep-walking) Narcolepsy
Summarise insomnia
Occurs in around one third of adults. Important to distinguish between temporary and chronic insomnia
How should insomnia be managed?
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
Describe the short term affects of barbiturate use in a patient with insomnia
Can be highly effective in the short term, greatly reducing the number of awakenings but preserving much of the original REM sleep
Describe the long term effects of barbiturate use in a patient with insomnia
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
What is the consequence in terms of REM sleep if a long term barbiturates user stops using the drug?
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
What is the consequence in terms of stages 3 and 4 S-wave sleep if a long term barbiturate user stops using the drug?
The levels of stage 3 and 4 sleep will revert back to normal level, but gradually, not displaying any rebound or overshoot features
Describe the manifestation of nightmares
They have a strong visual component and are seen during REM sleep when PGO (pontine-geniculo-occipital) spikes (APs) can be recorded
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
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
Describe night terrors
They are associated with intense feeling of fear. They are a non-REM phenomenon. They are common in PTSD
Describe somnambulism
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
Describe generally, narcolepsy
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
Describe the effects of narcolepsy on the body
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
Outline orexin and its relationship with narcolepsy
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
