what is EEG?
recording of electrical activity of pyramidal neurons in superficial layer of cortex. 1000s of neurons’ dipoles recorded through electrical signal and action potential
how to make EEG accurate
many trials, background noise is inherent because electrical activity must pass through many muting biological filters and environment is never perfect.
speed of the 4 EEG waves
Beta: >13Hz (14-30) (faster)
Alpha: 8-13 Hz
Theta: 4-7.5 Hz
Delta: 1-3.5 Hz (slower)
Beta waves
- High frequency, low amplitude
- awaken state
- conscious and logical though
- stimulating
- proper B allows for focus, memory, problem solving
- rises = anxiety
- suppression = depression, daydreaming
Alpha waves
- promote deep relaxation
- in daydreaming state or inability to focus
- high alpha seen when people are comfortable and relaxed
- suppressed = insomnia and anxiety
Theta waves
- associated with sleep or daydreaming
- increase intuition, creativity, feeling of being natural
- high theta = creativity, emotional connection, intuition, relaxation
- high theta WHILE AWAKE = impulsivity, depression, inattentiveness
- low theta = anxiety, poor emotional awareness
Delta waves
- Slowest
- most often in babies
- deepest relaxation, restorative/ healing sleep
- adequate amounts = rejuvenated, promotes immune system, natural healing
- can often be seen following brain injury = inability to think, learn, severe ADHD.
- when delta are suppressed = inability to revitalize and rejuvenate brain, poor sleeps
Non-REM sleep stage 1
more theta activity, loss of alpha, vertex sharp waves
Non REM sleep stage 2
theta and delta waves
vertex sharp waves
K complexes
sleep spindles
Non-REM sleep stage 3
higher voltage delta waves that are 20-50% of the background over time
Non-REM sleep Stage 4
more than 50% delta slow waves
REM sleep
- return of beta activity
- loss of muscle tone except in diaphragmatic muscles
- rapid eye movements
- dreaming
- 10 mins/ epoch (per cycle?)
- total REM/ night decreases with age. 8hrs at birth, 2hrs at 20yrs, 45mins at 70yrs
