EEG and Sleep - Karius Flashcards Preview

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Flashcards in EEG and Sleep - Karius Deck (31)
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1
Q

Gene activation/protein products set the circadian rhythm

A

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

2
Q

Retina-Hypothalamic tract

A

light/dark information

  • not vision
  • use cryptochrome receptors

direct relay to hypothalamus, does not use visual cortex

Glutamate - daylight
Melatonin - darkness

3
Q

Natural circadian clock

A

about 25 hours long - rough estimate

4
Q

Hypothalamus role

A

controls circadian rhythm and sleep induction/arousal separately

5
Q

Non-REM

A

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

Dreams - rehashing days events, not remembered

6
Q

REM sleep

A

rapid eye movement

EEG: low amplitude, higher frequency waves

  • eyes moving rapidly left/right
  • Associated with vivid dreams that you remember
7
Q

Inducing sleep

A

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

8
Q

Mechanism of homeostatic need for sleep

A

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)

9
Q

Induction of sleep at non-REM level

A

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

Tired when sick

10
Q

Growth spurt induction of non-REM sleep

A

GHRH triggers growth during sleep

NFkB released –> NO synthase –> NO

11
Q

Initiation of REM sleep

A

Lateral pontine tegmentum
-Cholinergic neurons

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

12
Q

Muscle paralysis in REM sleep

A

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
13
Q

Inducing arousal

A

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

14
Q

EEG - general features

A

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

15
Q

Alpha waves

A

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
16
Q

Beta Waves

A

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

17
Q

Alpha Block

A

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

18
Q

Gamma Waves

A

30-80 Hz
Occur when aroused or focused on something

Replaced by even more irregular activity if plan a motor response

Require hippocampus

19
Q

Theta Waves

A

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

20
Q

Delta waves

A

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
21
Q

EEG in infancy to childhood

A

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

22
Q

Factors decreasing frequency of alpha rhythm

A

hypoglycemia
Low body temperature
low adrenal glucocorticoids
high PaCO2

23
Q

Sleep cycle patterns

A

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
24
Q

Sleep cycles in children

A

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

25
Q

Sleep cycles in elderly

A
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
26
Q

Slow wave sleep on EEG

A

Stages N1, N2, N3

characterized by slowing of EEG

27
Q

N1

A

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

28
Q

N2

A

Stage 2 equivalent

True sleep

Physical characteristics:
EMGs show muscle activity, but relatively quiet

EEG characteristics:
Increasing voltage EEG
Slowing of frequency
Sleep spindles

29
Q

Sleep spindles

A

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)

30
Q

Deep Sleep

A

N3 in current guidelines

True sleep

Physical characteristics - deep sleep

EEG characteristics -
increasing voltage EEG
Slowing of frequency - theta and delta waves prominent

31
Q

REM sleep

A

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