Sleep Flashcards
What are the two types of sleep and their characteristics?
NREM : lot of brain activity, almost no sensory sensations, logical perseverative thoughts (will constantly think about the same thing), episodic and involuntary movement
REM: similar brain activity as awake, vivid sensations that are internally generated, illogical thoughts (dreams) and commanded movement inhibited.
What is sleep homeostasis?
Sleep homeostasis is a strong determinant of sleep duration. If you lose sleep, your body makes sure you sleep more to make up for it and the less you sleep, the harder it is to stay awake. You almost can’t bank sleep ahead of a sleep loss.
Why do we need to sleep (4 hypotheses?
Energy conservation purposes (only save 15%…)
Avoid predators (why shut down consciousness?)
Stress repair
Consolidate memory
What is the role of sleep in learning (3 proofs)?
They did an experiment where they REM-deprived sleep people and then reported performance identifying a figure learned the day before. When you are REM sleep deprived, you don’t consolidate what you learned the day before.
Also, you can see place cells in the hippocampus that are replaying in order or the environment explored during sleep.
Looked at human brain zones they trained during the day , and those regions become active again when you enter in REM sleep.
What is the role of sleep in stress repair (1 proof + 1 of the reasons)?
Rats that are sleep deprived die, but they never found a specific pattern, everything just gets really messy.
They put dye in the cerebro-spinal fluid and saw that sleep increases clearance of dye and consequently beta-amyloid from the brain. Therefore, sleep may help the brain to get rid of its metabolites!!
What is narcolepsy?
When a dog is excited, it falls asleep, it’s a defect in sleep-wake transition. You have:
- Loss of muscle tone triggered by excitment
- Sudden entry into sleep, especially REM sleep
- Intrusion of REM into the waking state so ++ hallucination and atonia
What is causing narcolepsy?
A mutation in Orexin/hypocretin peptide neurotransmitter system (mammals have two OX genes, OX1R and OX2R). Dogs are affected by a mutations of OX2R only while mice need to have all their orexin KO to get narcolepsy.
Where are located the orexin-releasing neurons and how are they acting on us?
They are located in the lateral hypothalamus and are active when we are awake: they must be active to maintain the awake state. They are responsive (active) to sound, novel food, novel environment, absence of fat and glucose (inhibitted by leptin and glucose). It also receives inputs from the suprachiasmatic nucleus.
What is mediating sleep homeostasis and how?
Adenosine accumulates in the body throughout the day, increasing your need to sleep (and the time you will spend sleeping). Caffeine seems to block Adenosine receptor 1 and not 2A.
Do flies sleep?
They enter into what we call quiescence.
What are the characteristic of fly quiescence?
1st: They have a moment of rest after 12 hours.
2nd: Cyc mutants are deprived in sleep and they have an increased mortality (mammals don’t need to be mutant to die from sleep deprivation).
3rd: flies have a moment in their circadian time where they are unresponsive to stimuli.
4. Sleep decreases with age, caffeine has the same effect, adenosine seems to be the main regulator of sleep homeostasis and metemphetamine keeps flies awake.
5. A subset of neurons control sleep(when they are inhibitted, they don’t sleep)
Do worms sleep?
When they shed their cuticle, they become quiescent which requires the circadian genes!! If they heated they become quiescent too (use it to repair stress)
