EEG and Sleep - Karius

Question 1

Gene activation/protein products set the circadian rhythm

Answer 1

Within the nucleus of SCN neurons

Clock (CLK)
BMAL1 - increase at night

Increase transcription/translation of:
Period genes (Per1-3)
Crytpochrome gene (Cry1-2)

Products inhibit Clock and BMAL1

Question 2

Retina-Hypothalamic tract

Answer 2

light/dark information

• not vision
• use cryptochrome receptors

direct relay to hypothalamus, does not use visual cortex

Glutamate - daylight
Melatonin - darkness

Question 3

Natural circadian clock

Answer 3

about 25 hours long - rough estimate

Question 4

Hypothalamus role

Answer 4

controls circadian rhythm and sleep induction/arousal separately

Question 5

Non-REM

Answer 5

Most time asleep is non-REM
Stages: 1, 2, deep
Progressive slowing of EEG waves

Dreams - rehashing days events, not remembered

Question 6

REM sleep

Answer 6

rapid eye movement

EEG: low amplitude, higher frequency waves

• eyes moving rapidly left/right
• Associated with vivid dreams that you remember

Question 7

Inducing sleep

Answer 7

Sleep homeostasis - need for sleep
-NREM sleep

Circadian clock tries to match need for sleep to darkness

Circadian clock triggers REM sleep

Ventral Preoptic Area (VPO) crucial

Question 8

Mechanism of homeostatic need for sleep

Answer 8

PGD2 in blood bind to DP receptor on endothelial cell of capillary –> release of adenosine from cell into the CSF

accumulation of adenosine throughout day - tired feeling

Adenosine bind to 2a receptors in Ventrolateral Preoptic area (VPO)

Question 9

Induction of sleep at non-REM level

Answer 9

IL1b, TNFa
NFkB released –> NO synthase –> NO

Tired when sick

Question 10

Growth spurt induction of non-REM sleep

Answer 10

GHRH triggers growth during sleep

NFkB released –> NO synthase –> NO

Question 11

Initiation of REM sleep

Answer 11

Lateral pontine tegmentum
-Cholinergic neurons

Axons to geniculate body - release Ach
-sends input to occipital cortex

Question 12

Muscle paralysis in REM sleep

Answer 12

crucial to prevent muscle activation during dreams

Locus Ceruleus - descending inhibition to alpha-motoneurons

• effective on large muscle groups
• spares diaphragm and small muscle groups

Question 13

Inducing arousal

Answer 13

lateral hypothalamus - orexin A and B (hypocretin 1 and 2)

orexigenic input sent to tuberomamillary nucleus (histamine)

Histamine released in locus ceruleus binds to H1 receptors, activating the LC neurons
-release NE and suppress REM sleep

Question 14

EEG - general features

Answer 14

Low voltage less than 200 uV
Frequency less than 1 Hz to more than 50 Hz
Differs over different parts of brain

Changes with degree of activity in the brain, arousal/awareness, sensory input.

No distinct “pattern”
Clear “patterns” pathological - seizure

Question 15

Alpha waves

Answer 15

8-13 hz
50 uV

quiet wakefulness - thinking with eyes closed

most prevalent over occipital cortex
disappear during sleep

Origin:

• requires connection between thalamus and cortex
• GABAergic neurons “force” coordination of neuronal activity
• feedback oscillation between thalamus and cortex creates waves

Question 16

Beta Waves

Answer 16

14-80 Hz
less than 50uV

alert wakefulness with eyes open

Most prevalent over frontal cortex, also parietal cortex

Origin: same as alpha
_sensory input disrupts oscillation to some extent

Question 17

Alpha Block

Answer 17

With sensory input - opening eyes

alpha wave cease, alpha block or alerting response

beta wave begin

Will persist as long as alert

when eyes closed again, alpha waves reappear

Question 18

Gamma Waves

Answer 18

30-80 Hz
Occur when aroused or focused on something

Replaced by even more irregular activity if plan a motor response

Require hippocampus

Question 19

Theta Waves

Answer 19

4-7 Hz
100 uV

Occurence:
Normal in children - parietal and frontal cortex

Adults - frustration or disappointment

Occur in sleep

Origin -
Hippocampus required, involved in production

Question 20

Delta waves

Answer 20

less than 3.5 Hz
100-200 uV

Occurrence:

• deep sleep in adults
• infants
• appearance during “wakefulness” sign of serious organic brain disease

Origin

• does not require connection between thalamus and cortex
• feedback oscillation within cortex creates waves
• indicate cortex is not longer connected to thalamus

Question 21

EEG in infancy to childhood

Answer 21

fast beta-like activity
over occipital region slow 0.5 - 2.0 Hz activity

Activity over occipital region gradually increase in frequency throughout childhood

adult alpha-wave appear during adolescence

Question 22

Factors decreasing frequency of alpha rhythm

Answer 22

hypoglycemia
Low body temperature
low adrenal glucocorticoids
high PaCO2

Question 23

Sleep cycle patterns

Answer 23

First cycle of night:

• 70-100 minutes in duration
• then moves to REM (short)

Later cycles:

• 90 min cycle length
• less time in deep sleep, more in REM

Question 24

Sleep cycles in children

Answer 24

More time in REM
More time in deep sleep
More total sleep time

Question 25

Sleep cycles in elderly

Answer 25

``` Fewer REM epochs (but they can be long) almost no deep sleep More frequent awakenings Less total sleep - more likely to nap Circadian rhythm is not a strong as it once was ```

Question 26

Slow wave sleep on EEG

Answer 26

Stages N1, N2, N3 characterized by slowing of EEG

Question 27

N1

Answer 27

stage 1 equivalent drowsiness/earliest stage of sleep Physical characteristics: - slow rolling movements of the eyes - EMGs show muscle activity EEG characteristics: Low voltage EEG slowing of frequency

Question 28

N2

Answer 28

Stage 2 equivalent True sleep Physical characteristics: EMGs show muscle activity, but relatively quiet EEG characteristics: Increasing voltage EEG Slowing of frequency Sleep spindles

Question 29

Sleep spindles

Answer 29

Begin to appear in N1, but are most prominent in N2 Bursts of alpha-like activity interrupting the slower EEG of sleep Often preceded by a sharp wave (K complex)

Question 30

Deep Sleep

Answer 30

N3 in current guidelines True sleep Physical characteristics - deep sleep EEG characteristics - increasing voltage EEG Slowing of frequency - theta and delta waves prominent

Question 31

REM sleep

Answer 31

Physical characteristics - rapid side to side eye movements - EMG becomes very quiet - locus ceruleus suppresses - dreams EEG characteristics - - rapid, low-voltage - similar to beta waves