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Neurology > Lecture 10 EEG, Sleep and Circadian Rhythm > Flashcards

Lecture 10 EEG, Sleep and Circadian Rhythm Flashcards

1
Q

Why does sleep occur

A

due to active inhibitory processes that originate in the pons

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2
Q

What is the consequence of the destruction of the brain stem at the level of the mid pons

A

creates a brain that never sleeps

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3
Q

Many neutrons within the reticular are ___

A

serotonergic (nerve ending that releases and is stimulated by serotonin)

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4
Q

Drugs that block serotonin formation would do what

A

Inhibit sleep

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5
Q

Serotonin is a precursor for what

A

Melatonin

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6
Q

What other structures are involved with the induction of sleep

A

Hypothalamus and Suprachiasmatic Nuclei

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7
Q

Damage to the SCN would do what

A

Disrupt sleep

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8
Q

Stimulation of the SCN would do what

A

Promote sleep

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9
Q

What is the purpose of the SCN

A

demonstrates 24hr circadian rhythm and controls release of melatonin from pineal gland

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10
Q

Light stimulates what type of neutrons in SCN

A

Inhibitory

Which inhibit the pineal gland releasing melatonin

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11
Q

Dark has what affect on SCN

A

Increased activity of SCN to increase the release of melatonin from pineal gland and the feeling of sleepiness

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12
Q

What is Melatonin linked to

A

The inhibition of Orexin

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13
Q

What is Orexin

A

Excitatory neurotransmitter released from the hypothalamus and is required for wakefulness

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14
Q

Defective orexin signalling would lead to what

A

Narcolepsy

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15
Q

What is a common treatment for depression where sleep disruption is present

A

Serotonin selective reuptake inhibitors

Increase serotonin levels in synapse

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16
Q

How would you assess the level of consciousness in an awake person

A

Look at behaviour, general alertness, speech patterns, speech content, reading, writing and calculating skills
Record brain activity using EEG

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17
Q

What is the purpose of an EEG

A

Recordings show patterns that reflect the electrical activity of the brain

18
Q

Frequency increases with__

A

Neuronal excitation (being awake)

19
Q

Amplitude decreases with ___

A

Increasing neuronal excitation (being awake)

20
Q

What EEG would you expect to see from someone who is awake

A

High frequency

Low amplitude

21
Q

What EEG would you see with someone who is awake by relaxed

A

High frequency

High amplitude

22
Q

What EEG would you expect to see with someone who is awake and alert

A

Higher frequency

Low amplitude

23
Q

What are 4 types of wave patterns seen in EEGs

A

Alpha
Beta
Theta
Delta

24
Q

Why is the amplitude low in an awake person

A

Brain when awake has a low amplitude because the brain is doing a lot of things lots of desynchronised waves cancel each other out

25
Q

Describe Theta waves and where they are seen

A

Low frequency
Amplitude varies
Stage 2 sleep cycle

26
Q

Describe Delta waves

A

Low frequency
High amplitude
Occur in deep sleep (stage 3 & 4)

27
Q

Describe alpha waves

A

High frequency and high amplitude (relaxed awake stage) sometimes stage 1

28
Q

Describe Beta waves

A

Even higher frequency and low amplitude (alert awake )

29
Q

What is REM sleep

A

During deep sleep where there are rapid eye movements

and where dreams occur (25% of sleep)

30
Q

What are the physiological characteristics of deep, slow wave sleep

A
  1. Deep sleep that occurs in the first hours of sleep
  2. Most restful type of sleep.
  3. Associated with decreased vascular tone (and therefore BP), respiratory and basal metabolic rate (hence drop in BT).
  4. Dreams may occur but are rarely remembered.
31
Q

Physiological characteristics of REM sleep

A
  1. Lasts 5-30mins every 90mins or so during a normal nights sleep, becoming more frequent as night progresses and rest and recovery are established.
  2. Dreams mostly occur in REM sleep
  3. Eye muscles show bursts of rapid activity. Profound inhibition of all other skeletal muscles due to inhibitory projections from pons to spinal cord
  4. REM sleep is dependent on cholinergic pathways within the reticular formation and their projections to the thalamus, hypothalamus and cortex. Anticholinesterases increase time spent in REM sleep.
  5. HR/RR become irregular and brain metabolism . EEG pattern mimics beta waves associated with highly alert, awake state.
  6. Very difficult to arouse an individual from REM sleep, although we often spontaneously awaken in the morning from this stage of sleep, vividly recalling our dreams.
  7. Whenever deprived of REM sleep, there is always a catch up when able to sleep again indicating that REM sleep must have an important physiological function.
32
Q

Why is sleep important

A
  1. Impairment of cognitive function
  2. Impairment of physical performance
  3. Sluggishness
  4. Irritability
  5. Psychosis has also been observed in some subjects.
33
Q

What does sleep support

A 
Neuronal plasticity
learning and memory
Cognition
Clearance of wast products from CNS
Conservation of whole body energy 
Immune function
34
Q

How does sleep change from childhood to adolescence to elderly

A

Percentage of REM sleep declines from 80% to 50% to 25%

May be absent in 80+

35
Q

Define insomnia

A

chronic inability to obtain the necessary amount or quality of sleep to maintain adequate daytime behaviour

36
Q

What are the 2 types of insomnia

A

Chronic, primary - no identifiable cause

Temporary, secondary- in réponse to pain, bereavement or crisis

37
Q

Define nightmares

A

strong visual component and are seen during REM sleep, typically occurring quite far on through the night. Waking will stop the nightmare and the individual will have a clear recollection of the “dream”.

38
Q

Define night terrors

A

occur in deep, delta sleep and are common in children 3-8 years, typically occurring early in the night. Children thrash and scream and may sit or stand up with their eyes open but are not properly awake and often fail to recognise their parents. The child does not remember the episode on waking the following morning.

39
Q

Define Somnambulism (Sleep-walking)

A

occurs exclusively in non-REM sleep, mainly in Stage 4 sleep and is more common in children and young adults, probably due to the decline in Stage 4 sleep with age

40
Q

Define Narcolepsy

A

Enter directly into REM sleep with little warning. Symptoms could be interpreted as intrusion of REM sleep characteristics onto the waking state.

Neurology (44 decks)

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