EEG & Sleep Flashcards
What does EEG stand for?
Electroencephalogram
Who was the EEG developed by?
Hans Berger in the 1930s
What does an EEG measure?
The sum of electrical activity generates by populations of neurones in the area
Advantages of an EEG
- non-invasive and cheap
- good temporal resolution
Disadvatange of an EEG
Poor spatial resolution
What is an MEG?
Magnetoencephalogram
What does an MEG measure?
Magnetic field evoked by current flow
Brain waves: normal awake, eyes closed
α rhythm, 8-13 Hz
Brain waves: normal awake, eyes open
ß rhythm, 14-25 Hz
Where do brain waves originate from?
Activity in the deep cerebral cortex
What is the wavelike nature derived from?
Cortico-thalamic oscillations
What kind of brain waves do normal, awake individuals show when their eyes are open?
y-rhythm, intermittent bursts, 30-80 Hz
Variations in α rhythms
α - visual cortex
Κ - α-like in auditory cortex
μ - α-like in sensorimotor cortex
What does the µ variation of brain waves in sensorimotor cortex also incline?
Mirror neuron activity
When are θ rhythms observed?
In early stage sleep
4-8 Hz
What is an epileptic discharge?
Small spike shown few seconds before seizure on EEG
Sleep stages: Non-REM sleep
1) α-rhythm, slow, drowsy
2) slowing, sleep spindles, light sleep
3) slowing, no spindles
4) δ (delta) waves - high amplitude, <4 Hz, deep sleep
At which stage may sleep walking occur?
Stage 4 of non-REM sleep
What are sleep spindles characterised by on an EEG?
Little bursts
What is the role of non-REM sleep?
- Restorative
Loss evokes homeostatic breakdown in animals, humans can last 12 days
What kind of rhythms are shown on an EEG during REM sleep?
ß rhythms
What occurs during REM sleep?
Dreaming
What is the role of REM sleep?
Laying down memories
Levels of what decrease in people with sleeping disorders?
Orexin
What is secreted from the pineal gland which influeces the sleep/wake cycle?
Melatonin
At what time of day is melatonin secreted?
Night time
When is serotonin secreted to influence the sleep/wake cycle?
During the day when there is lig
What is the sleep probability a balance of?
Process S - sleep, energy, debt
Process C - circadian rhythm
