Title: Psychology / Biopsychology / 14_Sleep
Tags: Biopsychology::14_Sleep Biopsychology::Semester_2

Q: What was found out about the effect of sleep on fruit flies?
A: Sleep is not necessary for the vital functions of fruit flies.

Q: What is the world record for "longest time awake" for humans?
A: 11 Days (264 hours)

Q: How does the proportion of REM sleep change when aging?
A: Decreases steadily until the age of 13

Q: What happens to body temperature when sleeping?
A: It is lowered by about one degree

Q: What happens to growth and stress hormones while sleeping?
A: Growth hormone is released during the first half of the night
Cortisol is released during the second half of the night → activates the sympathetic nervous system

Q: What is our "internal clock" called?
A: Suprachiasmatic nuclei (SCN is also fine)

Q: How are the suprachiasmatic nuclei adjusted?
A: They are light-sensitive ganglion cells that receive input from the retina to adjust the internal clock to the day-night cycle.

Q: What happens to the internal clock if there is no external "zeitgeber"?
A: The internal rhythm of the SCN is followed (but typically changes to 25 hours)

Q: What happens when there is a lesion to the suprachiasmatic nuclei?
A: The affected being does not have a regular sleep-wake rhythm anymore.

Q: How do the suprachiasmatic nuclei work?
A: They have a special "clock gene" that modulates the protein synthesis rate, leading to fluctuations in neural activity/the firing rate of neurons.

Q: What are the 5 Stages of sleeping?
A: Stage 1 - 4 of non-REM
REM sleep

Q: Why is REM called "paradoxical sleep"?
A: Eye movements are rapid, the heart rate and EEG signal resemble that of an awake person all the while the body is paralyzed.

Q: Why is it difficult to identify REM sleep on the EEG?
A: The EEG signal is really similar to that of an awake person.

Q: What 2 indicators can be seen on EEG signals to determine if a person is asleep?
A: 1. "sleep spindles" firing with 12-15 Hz for 0.5-1 seconds
2. "K complex" high voltage wave with really high amplitude

Q: What is the difference between alpha, theta and delta rhythms?
A: The amplitude, frequency, and sleep stage at which they appear
Alpha: high frequency, low amplitude → awake and REM sleep
Theta: lower frequency and higher amplitude → stage 1 and 2 sleep
Delta: low frequency and high amplitude → Stage 3 and 4 sleep

Q: How is the cortex activated during REM sleep?
A: high activity of visual cortex and limbic brain areas
downregulation in the rest of the cortex

Q: What 4 effects happen when sleep is initiated?
A: 1. Less activity in the Ascending Reticular Activating System
2. Deactivation of the locus coeruleus
3. Increase in GABAergic activity in the cortex → inhibition leasing to less activation through sensory inputs
4. Histamine and orexin release at the hypothalamus is reduced

Q: What two kinds of activations happen during the transition from non-REM to REM sleep?
A: PGO Spikes
Activation of REM-on cells

Q: What are PGO spikes?
A: activation patterns that start in the pons, then appear in the geniculate nucleus of the thalamus and finally appear in the occipital cortex → every spike is associated with an eye-movement

Q: How does the proportion of REM sleep change during regular sleep?
A: Less REM in the early hours of sleep, more REM in the late hours of sleep

Q: What paralyzes the body during REM?
A: Activity that is descending from the brain to the muscles is stopped by the pons.

Q: How does consolidation of learned things differ during early and late sleep?
A: early non-REM sleep: better consolidation of declarative memory
late REM sleep: better consolidation of non-declarative memory

Q: During which sleep phase can memory consolidation be boosted with external cues?
A: During non-REM sleep (slow wave)

Q: Which activation patterns do place cells display during sleep?
A: Place cells are activated in the same order as they are during exploration making for a "hippocampal replay".
(some activation patterns seem to also transfer to the visual cortex)
This effect looks like rats are "dreaming" of running through the maze.