Sleep/Wake Cycle

Question 1

What is an EEG

Answer 1

electroencephalograph-
measures excitation of the dendrites in the cerebral cortex (measures activity)

Question 2

What is an EOG?

Answer 2

electrooculograph-
measures eye movement

Question 3

What is an EMG?

Answer 3

electromyograph-
measures muscle tone

Question 4

What is a polysomnograph

Answer 4

EEG, EOG, and EMG together-
used to measure sleep in humans

Question 5

What are EEG waves distinguished by?

Answer 5

amplitude and frequency

Question 6

Is cortical activity seen in an EEG a reflection of sleep or causative of sleep.

Answer 6

relective

Question 7

what brain structures are associated with sleep

Answer 7

brainstem and diencephalic structures

Question 8

When a person is awake, what type of waves do they have?

Answer 8

beta

Question 9

When a person is drowsy, what waves do they have?

Answer 9

alpha

Question 10

When a person is in stage 1 sleep, what waves do they have

Answer 10

theta

Question 11

When a person is in stage 2 sleep, what waves do they have

Answer 11

sleep spindles and K complexes

Question 12

When a person is in stage 3/4 sleep, what waves do they have?

Answer 12

delta

Question 13

When a person is in REM sleep, what waves do they have?

Answer 13

look like beta waves, but with sawtooth waves

Question 14

What stages have synchronous vs asynchronous waves? What does that mean?

Answer 14

The stages of sleep start as very asynchronous (with wake being the most so) and get more synchronous (with stage 4 being the most so) until they reach REM, which is very asynchronous. Higher levels of synchronization mean that more neurons are firing together.

Question 15

Describe the stages of non-REM sleep and behavioral aspects of each.

Answer 15

Stage 1-drifting sensation
Stage 2- light sleep
Stage 3- vital signs drop (BP, pulse, breathing rate) (slow metabolic and neurological function)
Stage 4- deep sleep, very difficult to wake (sensory threshold very high)

Question 16

What are stage 3 and 4 of nREM sleep known as? What are they important for?

Answer 16

known as slow wave sleep. important for development and memory

Question 17

what is REM sleep also known as?

Answer 17

active sleep or paradoxical sleep

Question 18

what are the behavioral aspects of REM sleep

Answer 18

complete atonia (lack of muscle tone), rapid eye movements, myoclonic twitches, vital signs increase, body temp is not well regulates (drops), vivid dreams, EEG resembles awake person, penile and clitoral tumescence (increased blood flow)

Question 19

what is penile tumescence in REM sleep used to diagnose

Answer 19

whether an erectile dysfunction is physiological or psychological

Question 20

describe the order of sleep stages throughout one cycle

Answer 20

awake, 1, 2, 3, 4, 3, 2, 1, REM ….

Question 21

Describe the length of sleep stages throughout the time someone is asleep.

Answer 21

Stage 4 gets shorter (and we sleep less deeply) throughout the night. REM sleep gets longer throughout the night.

Question 22

What did Constantin von Economo study? What were his findings?

Answer 22

the brains of people who died from the Spanish flu. Lesions in the diencephalon and mesencephalon led to coma-like sleeping sickness or insomnia. Those areas have a large amount of control over sleep/wake cycles.

Question 23

What is RAS

Answer 23

reticular activating system - part of the reticular formation, involved in waking people up. Also enhanses sensory tract signals (except for olfaction)

Question 24

What is the basal forebrain

Answer 24

Releases acetylcholine and GABA to promote wakefulness in the cerebral cortex

Question 25

What is the ascending activating system?

Answer 25

RAS and BF working together

Question 26

What is the VLPO

Answer 26

ventrolateral preoptic nucleus- located in hypothalamus of the diencephalon projects to wake promoting brain areas to release inhibitory neurotransmitters GABA and galanin

Question 27

lesions in the VLPO can lead to...

Answer 27

decreased nREM and REM sleep, and sleep fragmentation

Question 28

what is the flip flop switch model

Answer 28

both sides of the switch inhibit each other so when one is on, the other cannot be on (no in-between state)

Question 29

When awake, what does the flip flop sleep switch look like?

Answer 29

RAS and BF inhibit VLPO. Lateral hypothalamus inhibits VLPO using GABA, orexin activates ascending arousal system (RAS and BF)

Question 30

When asleep, what does the flip flop sleep switch look like?

Answer 30

VLOP inhibits RAS/BF with GABA and galanin, VLPO also inhibits the lateral hypothalamus using those neurotransmitters. Orexin stimulation of RAS/BF is decreased.

Question 31

What is the "finger on the switch" stabilizing the sleep flip flop switch?

Answer 31

orexin neurons in the lateral hypothalamus

Question 32

What is narcolepsy

Answer 32

a condition where an individual loses orexin (hypocretin) neurons. Often conceptualized as REM intruding into wakefulness

Question 33

what are some symptoms of narcolepsy?

Answer 33

overwhelming sleepiness during the day, cataplexy (sudden loss of muscle tone in response to intense emotions - usually positive), sleep paralysis, hallucinations, fragmented sleep at night

Question 34

What is REM behaviro Disorder

Answer 34

loss of normal muscle atonia during REM sleep.

Question 35

a person with RBD will do what while asleep

Answer 35

while in REM they will act out dreams (usually violent)

Question 36

RBD is a strong predictor of what?

Answer 36

future neurodegenerative diseases like parkinson's or Lewy Body dementia (synucleinopathy)

Question 37

What causes RBD

Answer 37

unclear but lesions in brainstem can result in behavioral phenotype

Question 38

What is the two process model of sleep

Answer 38

process S which is sleep drive, increases with time spent awake (adenosine) process c which is alertness which oscillates with a circadian rhythm (wake drive)

Question 39

What is adenosine

Answer 39

a byproduct of ATP use, builds up during the time a person is awake. Sleep reduces adenosine. Sleep driver.

Question 40

What are the two types of adenosine receptors? Are they excitatory or inhibitory? What cells are they on?

Answer 40

A1-on wake-promoting cells in RAS and BF, inhibitory receptor A2a- on sleep promoting cells in VLPO, excitatory receptor

Question 41

What is the mechanism of action for caffeine in the brain?

Answer 41

Caffeine has a similar shape to adenosine. It binds to adenosine receptors A1 and A2a but doesn't activate them, meaning adenosine can't bind and promote sleep.

Question 42

How is process C regulated

Answer 42

The SCN regulates process C through a multi-synaptic neural pathway (sends neural connections to sleep and wake-promoting regions in the brain)