Background info Flashcards
Are neurons somewhat synchronized in regular firing rhythms, known as “brain waves”?
yes
Where are electrodes placed?
On the scalp and in pairs
What are EEG signals affected by?
cerebral cortex’s state of arousal
Do EEGs show slow or fast changes in membrane potentials?
Slow
Where do EEG waves arise
thalamus
Name a location of an input that affects this location
the brainstem reticular
formation
Alpha
- (8-13 Hz; 30-50 uV avg. amplitudes)
- relaxed state and eyes are closed
How are alpha waves decreased?
eye opening + mental effort
Alpha waves: Cortical activatiion relationship
greater activation = lower alpha activity
Strong areas of alpha waves
occipital and frontal cortex
Beta
- (13-30 Hz; < 20 uV)
- Awake, alert, eyes open
How are beta waves decreased?
absent or reduced in areas with cortical damage + sedative-
hypnotic drugs
Theta
- (4-8 Hz; < 30 uV)
- awake children up to adolescence; can’t been seen in adults; seen in sleep at all ages
Low theta
- (4-5.45 Hz)
- Activities with decreased arousal & increased drowsiness
High theta
- (6-7.45 Hz)
- tasks involving working memory
Delta
- (0.5-4 Hz; up to 100-200 uV)
- sleep stages 3 and 4 (not seen in conscious adult)
- Highest amplitude out of all EEG waves
- Jaw/neck muscles movement make these waves as well
Gamma
- (30-50 Hz)
- Higher mental activity association, disappears under general anesthesia
- Enhanced in monks because of meditation, absent in schizophrenics
The more active the brain, the ____ the frequency and the _____ the amplitude of the EEG
- higher, lower
- The inverse holds true
What are the two states of sleep?
REM and non-REM
How many phrases does non-REM sleep have? Is it progressive?
Yes, it is progressive, N1-N3
How long does the REM cycle last?
about 90 minutes
About how many times does the REM cycle repeat in a span of 8 hours?
4-6 times
What happens during the latter REM cycle?
REM component gets longer while N3 gets shorter/not
occurring
N1
- Decreased beta activity
- Alpha activity less obvious
- Theta activity emerges