Flashcards in Sleep and Arousal Deck (30)
Describe EEG characteristics of awake stage
1. Low amplitude
2. Random (desynchronized)
3. High frequency
Describe EEG characteristics of drowsy stage
8-12 Hz alpha waves
Describe EEG of stage 1 sleep
3-7 Hz theta waves
Describe EEG of stage 2 sleep
1. 12-14 Hz
2. Sleep spindles (high freq)
3. K-complexes (jolt response stage, high amplitude)
Describe EEG of Delta sleep
1. High amplitude
2. Slow (.5-2 Hz)
Describe EEG of REM sleep
Mimics awake EEG
Which stage of sleep exhibits fast eye movements?
What are the features of night’s sleep?
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
What are features of the ascending reticular activating system (ARAS)
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)
Which nucleus does histamine come from?
Which nucleus does noradrenaline come from?
Which nucleus does 5-HT come from?
Which nucleus does Ach come from?
Basal forebrain, pedunculopontine tegmental nucleus (PPN)
Where does hypocretin/orexin come from?
Posterior lateral hypothalamus
What neurotransmitters promote WAKEFULNESS?
Describe thalamocortical neuron electrophys during sleep
1. Burst firing (burst-pause, burst-pause and so on)
2. Vrev = -65 mV
Describe thalamocortical neuron electrophys during wakefulness (2)
1. Tonic (continuous) firing
2. Depolarizing current leads to higher RMP (-58 mV)
What are the characteristics of REM sleep
1. EEG activation (desynchronized activity)
2. Muscle atonia (loss of muscle tone)
3. Episodes of rapid eye movements, slight muscle twitches
What neuronal activity causes REM to begin
1. Serotonin, Noradrenaline, histamine STOP firing
2. Ach neurons START firing
3. SOME Hypocretin neurons STOP, SOME START firing
Describe circuit during waking
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
Describe circuit for non-REM sleep
1. GABA from preoptic area inhibits Hypocretin and LC/DRN/TM
2. AVERAGE Ach firing
Describe circuit during REM sleep
1. GABA from periaqueductal gray inhibits ONLY LC/DRN/TM complex
2. INCREASED Ach (PPN) firing
What creates desynchronized brain activity during wakefulness?
All the wakefulness neurotransmitters modulate thalamus differently, creating desynchronized activity
What creates synchronization observed during NREM sleep?
VLPO (Ventrolateral preoptic area) inhibits all the wakefulness nuclei (locus coeruleus, dorsal raphe etc) using GABA
What creates REM activity (circuit elements)?
1. Hypocretin acts on thalamus
2. Ach acts on thalamus
3. VLPO + PAG inhibit all nuclei
Which nucleus is responsible for the visible characteristics of REM sleep? What are they (3)?
Pedunculopontiine tegmental nucleus
1. Rapid eye mvt
2. HR, BP variability
3. Muscle atonia (SC projections)
What controls when we are awake or asleep?
1. Homeostatic rhythm (how much sleep you want to get)
2. Circadian rhythm (based on time of day)
Where in the sleep control system does caffeine play a role?
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
Where in sleep control system does melatonin play a role?
1. Melatonin produced by pineal gland, released into circulation
2. Production INHIBITED by light, PERMITTED by darkness circadian rhythm