EEG and sleep

Question 1

zeitgebers

Answer 1

environmental timing cues that affect circadian rhythm e.g. sunlight

Question 2

endogenous

Answer 2

from within

Question 3

periodicity of circandian rhythm

Answer 3

24hours

Question 4

where is suprachiasmatic nucleus

Answer 4

in the anterior hypothalamus

Question 5

what does suprachiasmatic nucleus do

Answer 5

regulates timing of sleep

not sleep itself

Question 6

day light has lots of which wavelength

Answer 6

blue wavelength (which helps us wake up)

Question 7

melatonin

Answer 7

sleep hormone

naturally accumulates as day goes on, and by evening you are tired

Question 8

sleep defined as

Answer 8

reduced motor activity

reduced response to stimulation

stereotypic postures (eyes closed in humans)

relatively easy reversibility

Question 9

electromyography

Answer 9

electrical activity of muscles

Question 10

extrooculuography

Answer 10

elextrical activity from the eyes

Question 11

EEG measures

Answer 11

synchronous electrical activity from LARGE populations of neurones in the brain

caused by cellular ionic movement, which creates an electric field

Question 12

each scalp electrode of EEG

Answer 12

is the summation of many millions of neurones all of a similar spatial orientation

Question 13

pros/cons of EEG

Answer 13

non invasive 
easy to administer
data easily gathered
high temporal resolution 
(event generated potentials)

low spatial resolution
electric fields follow an inverse square law so only cortical activity detectable (smaller the further distance away- so the surface cortex can only be recorded)

Question 14

non REM sleep

characterisitcs

Answer 14

neuronal activity is low
not music action potential firing between neurones

metabolic rate and brain temperature at their lowest

heart rate and blood pressure decline (decreased sympathetic nervous system outflow)

increase in parasympathetic outflow dominates no REM sleep- constricted pupils

muscles tone and reflexes still in tact e.g. knee jerk

Question 15

stage 1 sleep

Answer 15

drowsiness
awakened easily

eyes move slowly and muscle activity slows

sudden muscles contractions preceded by a sensation of falling

transitions from wakefulness to onset of sleep- several minutes

Question 16

EEG activity for awake people

Answer 16

low voltage (10-30μV@16-25Hz)

as they relax- sinusoidal (alpha) activity 20-40μV@10Hz

activity of mixed frequencies

Question 17

EOG of stage one

Answer 17

eyes show slow, rolling movements

Question 18

EMG of stage one

Answer 18

some muscular activity

Question 19

stage 2

Answer 19

light sleep

eye movement STOPS
and brain waves become slower with only occasional burst of activity

the body temp drops, heart rate slows

Question 20

stage 2 EEG

Answer 20

characterised by bursts of sinusoidal waves called ‘sleep singles’ (12-14 Hz) and biphasic waves called K complexes

Question 21

biphasic

Answer 21

up and down relative to baseline

Question 22

k complexes

Answer 22

occur episodically against background of continuing low-voltage EEG activity

Question 23

stage 3

Answer 23

deep sleep

extremely slow delta waves, interspersed with smaller, faster waves

sleep walking, night terrors, talking, bedwetting ‘parasomnia’

occur during the transitions between non REM and REM sleep

FUGE state- disorientation, hallucination, irritability

Question 24

stage 3 EEG

Answer 24

high amplitude, slow delta waves (0.5-2Hz)

Question 25

stage 4

Answer 25

very deep sleep brain shows delta waves almost exclusively disorientation for several mins following arousal from this stage

Question 26

stage 5

Answer 26

REM sleep EEG mimics wakefulness closed eyes move rapidly from side to side low voltage mixed frequency 'paradoxical sleep'

Question 27

stage 5 | Neurones in Pons of brainstem, lateral geniculate nucleus and occipital cortex

Answer 27

neurons in pons of brainstem, lateral geniculate nucleus and occipital cortex fire in more intones burst during REM that in wakefulness

Question 28

intense firing generates high voltage spike potentials in EEG called

Answer 28

ponto-geniculo-occipital spikes PGO

Question 29

PGO type spikes can be produced in alert subjects by startling them with an abrupt stimuli like a loud noise suggesting..

Answer 29

PGO of REM sleep may be activated by the same neural circuits that initiate the 'startle response' PGO are also correlated with bursts of eye movements in REM sleep

Question 30

during REM sleep

Answer 30

brain temp and metabolic rate rise - consistent with increased neural activity in some areas- greater than in walking! all skeletal muscles are atonic muslces controlling movements of eyes, middle ear ossicles, and diaphragm remain active (so you can breathe and hear impeding danger!) penile erections in men clitoral engorgement in women (controlled by parasympathetic nervous system) pupils highly constricted (mitosis) respiration is unrespeosive to change on blood pCO2 responses to heat and cold reduced or even absent- body temp drifts toward ambient

Question 31

atonic

Answer 31

flaccid and paralysed

Question 32

so why is sleep not a continuum from light to deep sleep

Answer 32

Each phase is behaviourally complex and reflects the physiological mechanisms representing a distinctive brain state REM could be said to be a lighter sleep since arousal is easier than in stages 3-4 Non-REM could be said to be lighter sleep because body temp, muscle tone and reflexes are all maintained.

Question 33

normal human sleeping patterns

Answer 33

After 70-80 minutes sleeper returns to stages 3 or even 2 before entering first REM phase of the night which lasts 8-10 minutes. Time from first stage to end of REM = 90-110minutes Repeated four or five times per night-during each repetition, stages 3 & 4 decrease in duration and REM increases

Question 34

in young adults what percentage of sleep spent in stage 1

Answer 34

only 5%

Question 35

in young adults, the largest amount of sleep occurs in what stage?

Answer 35

50-60%

Question 36

what percentage of sleep in young adults is 3-4 stages

Answer 36

15-20%

Question 37

REM phases of sleep constitute what percentage in young adults

Answer 37

20-25%

Question 38

theories of dreaming

Answer 38

strange-imagery brain not fully functioning exerceises synapses when no external activity memory consolidation circuit testing