Sleep and Arousal

Question 1

Describe EEG characteristics of awake stage

Answer 1

1. Low amplitude
2. Random (desynchronized)
3. High frequency

Question 2

Describe EEG characteristics of drowsy stage

Answer 2

8-12 Hz alpha waves

Question 3

Describe EEG of stage 1 sleep

Answer 3

3-7 Hz theta waves

Question 4

Describe EEG of stage 2 sleep

Answer 4

1. 12-14 Hz
2. Sleep spindles (high freq)
3. K-complexes (jolt response stage, high amplitude)

Question 5

Describe EEG of Delta sleep

Answer 5

1. High amplitude
2. Slow (.5-2 Hz)
3. Synchronous

Question 6

Describe EEG of REM sleep

Answer 6

Mimics awake EEG

Question 7

Which stage of sleep exhibits fast eye movements?

Answer 7

REM stage

Question 8

What are the features of night’s sleep?

Answer 8

1. Initially deeper sleep (go to stage 4) but as night goes on, go less and less deep
2. REM states get longer in time and not as far apart as initially

Question 9

What are features of the ascending reticular activating system (ARAS)

Answer 9

1. Fell firing rates change with behavioral state
2. Diffuse innervation of brain regions
3. Projections between different brain regions
4. Modulatory neurotransmitters (not glutamate)

Question 10

Which nucleus does histamine come from?

Answer 10

(Tuberomammillary nucleus)

Question 11

Which nucleus does noradrenaline come from?

Answer 11

Locus Coeruleus

Question 12

Which nucleus does 5-HT come from?

Answer 12

Dorsal raphe

Question 13

Which nucleus does Ach come from?

Answer 13

Basal forebrain, pedunculopontine tegmental nucleus (PPN)

Question 14

Where does hypocretin/orexin come from?

Answer 14

Posterior lateral hypothalamus

Question 15

What neurotransmitters promote WAKEFULNESS?

Answer 15

1. Histamine
2. Serotonin
3. Norepinepherine
4. Acetylcholine
5. Hypocretin/Orexin

Question 16

Describe thalamocortical neuron electrophys during sleep

Answer 16

1. Burst firing (burst-pause, burst-pause and so on)

2. Vrev = -65 mV

Question 17

Describe thalamocortical neuron electrophys during wakefulness (2)

Answer 17

1. Tonic (continuous) firing

2. Depolarizing current leads to higher RMP (-58 mV)

Question 18

What are the characteristics of REM sleep

Answer 18

1. EEG activation (desynchronized activity)
2. Muscle atonia (loss of muscle tone)
3. Episodes of rapid eye movements, slight muscle twitches

Question 19

What neuronal activity causes REM to begin

Answer 19

1. Serotonin, Noradrenaline, histamine STOP firing
2. Ach neurons START firing
3. SOME Hypocretin neurons STOP, SOME START firing

Question 20

Describe circuit during waking

Answer 20

1. Hypocretin excites VTA (Dopamine), Basal forebrain (Ach), LdT, PPT /PPN(Ach), LC, DRN, TM
2. LC, DRN, TM inhibit LdT, PPT, causing a decrease in Ach production

Question 21

Describe circuit for non-REM sleep

Answer 21

1. GABA from preoptic area inhibits Hypocretin and LC/DRN/TM
2. AVERAGE Ach firing

Question 22

Describe circuit during REM sleep

Answer 22

1. GABA from periaqueductal gray inhibits ONLY LC/DRN/TM complex
2. INCREASED Ach (PPN) firing

Question 23

What creates desynchronized brain activity during wakefulness?

Answer 23

All the wakefulness neurotransmitters modulate thalamus differently, creating desynchronized activity

Question 24

What creates synchronization observed during NREM sleep?

Answer 24

VLPO (Ventrolateral preoptic area) inhibits all the wakefulness nuclei (locus coeruleus, dorsal raphe etc) using GABA

Question 25

What creates REM activity (circuit elements)?

Answer 25

1. Hypocretin acts on thalamus 2. Ach acts on thalamus 3. VLPO + PAG inhibit all nuclei

Question 26

Which nucleus is responsible for the visible characteristics of REM sleep? What are they (3)?

Answer 26

Pedunculopontiine tegmental nucleus 1. Rapid eye mvt 2. HR, BP variability 3. Muscle atonia (SC projections)

Question 27

What controls when we are awake or asleep?

Answer 27

1. Homeostatic rhythm (how much sleep you want to get) | 2. Circadian rhythm (based on time of day)

Question 28

Where in the sleep control system does caffeine play a role?

Answer 28

1. Caffeine is an adenosine receptor antagonist (BLOCKS adenosine receptors) 2. Adenosine increases each hour the animal is awake , so an antagonist keeps adenosine levels low (think that you haven’t been awake for that long)  homeostatic rhythm

Question 29

Where in sleep control system does melatonin play a role?

Answer 29

1. Melatonin produced by pineal gland, released into circulation 2. Production INHIBITED by light, PERMITTED by darkness  circadian rhythm

Question 30

What are 4 symptoms of narcolepsy?

Answer 30

1. Falling asleep at inappropriate times 2. Sudden loss of muscle tone 3. Sleep paralysis 4. Hallucinations: Go very quickly into REM sleep, hard to distinguish reality