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32 Cards in this Set
- Front
- Back
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Describe the physiological changes that differ between sleep and wake. |
Conscious vs. unconscious Body temperature is about 1°C lower when sleeping Breathing rate decreases and is more rhythmic during sleep Heart rate decreases during sleep Different brain activities |
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What is an excitatory post synaptic potential?
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A post-synaptic potential that causes the post synaptic cell to depolarize, making it more likely to fire an AP. |
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What does EEG (electroencephalogram) measure?
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Neural (brain activity)changes during wake and sleep. It can detect IPSPs and EPSPs. |
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Which two things are necessary for EEG to record brain activity? |
A population of neurons to fire in sync and alignment of the neurons in the neocortex |
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What is EOG and what does it measure? |
Measures eye movements during sleep |
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What is EMG and what does it measure? |
Electromyography Measures the electric activity in the muscles |
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What does frequency measure? What does Hz represent? Describe the characteristics of frequency bands (e.g. alpha, theta, delta) |
Frequency measures the rate at which something occurs. (refers to the firing rate of the neurons)
Hz represents Hertz, the units for frequency (i.e. 1 hertz = 1 cycle/sec). Alpha waves: 8-13Hz, occurs when awake and resting; fast, low amplitude waves that are desynchronized Beta waves: 14-30 Hz, occurs when awake with mental activity; fast, low amplitude waves that are desynchronized Theta: 4-7 Hz, occurs during sleep; slow, high amplitude waves that are synchronized Delta: less than 3.5 Hz, occurs during deep sleep; slow, high amplitude waves that are synchronized |
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Contrast the EEG recording for wake and NREM sleep. What is the dominant frequency during wake and NREM sleep? |
Wake EEG recordings: fast, low amplitude, and desynchronized waves (beta & alpha waves) NREM sleep recordings: slow, high amplitude, and synchronized waves (delta & theta waves) |
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Why is the amplitude of the EEG signal larger during NREM sleep than wake? |
During sleep, brain activity slows down, and neurons fire more in snychrony.
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What is the ascending activating system? Which regions are involved? |
The AAS is the part of the brain that receives general sensory input from the body. It involves of the RF, the medulla, the pons, the thalamus, and the cortex. |
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What is the reticular formation and what role does it play in sleep wake behavior? |
The RF is the part of the ascending activating system that wakes up the cortex. |
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How does the sound of your alarm clock impact the activity of the reticular formation and cortex? |
A loud noise desynchronizes brain waves causing you to wake up. RF will send a signal to thalamus, which will relay it to the cortex, stimulating it to wake up. |
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What would happen if the Reticular Formation was damaged? |
It would cause you to be in a coma, since there would be nothing to wake up your cortex. |
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What would happen if the Reticular Formation were always active? |
One would have trouble falling asleep. |
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What nuclei are involved in arousal promoting and what neurotransmitters do they release? |
LC (locus coeruleus): norepinephrine Raphe (dorsal & median raphe nuclei): serotonin TMN (tuberomamillary nucleus): histamine |
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What nuclei are involved in sleep promoting and what neurotransmitter do they release? |
VLPO (ventrolateral preoptic area): GABA |
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Describe the interaction between VLPO and the ascending activating system (AAS). How does the interaction between the VLPO and AAS impact sleep/wake behaviour? |
During wake, the RF sends inhibitory post synaptic potentials to the VLPO, while during sleep, the VLPO inhibts the RF. The two work through mutual inhibition; this prevents the possibility of intermediate states of sleep. |
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How would a deficit in orexin impact sleep/wake behavior? |
A deficit in orexin would cause narcolepsy, a condition where an individual will have trouble staying awake. |
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How does orexin impact sleep/wake behaviour? |
Orexin is a hormone secreted by the LHA (lateral hypothalmic area) and it reinforces the sleep-wake switch by keeping the RF awake. |
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What role does the thalamus play in sleep/wake transition? Describe burst and spike mode. Which mode is on when you are awake vs. sleeping? Which state is dependent on inputs from the ascending activating system? |
The thalamus relays info to the cortex and is modulated by the AAS. Stimulation of the RF induce spike mode in the thalamus, causing desycnhronized EEG to wake you up. A burst mode involves involves bursts of APs in the thalamus, causing synchronized brain activity in the cortex; this occurs during sleep; AAS is inhibited. A spike mode involves an incoming excitatory signal from the AAS and produces a single AP in the thalamus causing desynchronized activity in the cortex. The thalamus will constantly feed the cortex input; this occurs during wake |
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What would happen if the thalamus was stuck in spike mode? |
You would never fall asleep. |
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What would happen if the thalamus was stuck in burst mode? |
You would never wake up |
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What is fatal familial insomnia and how does it impact the sleep/wake transition |
A more permanent version of insomnia in which an individual constantly tries but fails to fall asleep. The individual will constantly be in spike mode. |
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Describe how circadian factors contribute to the sleep/wake cycle? |
The circadian rhythm keeps us on a 24 hour clock. It counteracts homeostatic sleep pressure during the day by inhibiting melatonin, and weakens and makes us sleepy during the night through the release of melatonin. It helps regulate body temperature levels, stress levels, neural activity, and hormone levels throughout the day. It is controlled by the PER (period) gene and it can be set by external cues (i.e. sunlight, alarm clock) |
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What brain region controls our circadian rhythm? |
SCN (Suprachiasmatic Nucleus) |
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What is the PER gene? Is it the same in everyone, and if not, what impact does this have on sleep/wake behaviour? |
It is the gene that regulates the endogenous circadian rhythm, keeping us roughly on a 24 hour clock. It is not the same in everyone and it can vary in timing (i.e. some people may have PER genes that work on a 18 hr clock, or 26 hr clock). Those with a longer clock may have more trouble falling asleep at night than those with a shorter clock. |
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What are Zeitgebers? What role do they plan in the circadian rhythm? |
Zeitgebergs are external cues (e.g. sunlight, alarm clock, meals) that allow us to exogenously reset our clocks. |
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What is melatonin? |
A hormone that induces sleepiness |
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What is the homeostatic factor that causes sleepiness? What causes the build up of this factor? How does this relate to the pressure to sleep? |
Adenosine During the day, the brain is active and breaks down ATP, leaving adenosine as a byproduct. Adenosine is what drives sleep pressure throughout the day. Increased levels of adenosine inhibit the arousal system and activate the VLPO, triggering sleepiness. |
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Why does coffee work to keep you awake?
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Coffee blocks adenosine's inhibitory function (on the arousal system). |
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What impact does adenosine have on VLPO |
It promotes VLPO activity. |
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What impact does adenosine have on the AAS? |
Adenosine inhibits the ASS. |
