9.3 Why Sleep? Why Rem? Why Dream? Flashcards
____ serves many functions. During sleep, we rest our muscles, decrease metabolism, rebuild proteins in the brain, reorganise synapses, and strengthen memories.
Sleep
You feel tired at the end of the day because ____ processes in your brain force you to become less aroused and less alert.
inhibitory
People who don’t get enough sleep have trouble concentrating and become more vulnerable to illness, especially ____ ____.
mental illness
Even one night of sleeplessness activates the ____ ____. That is, you react to sleep deprivation as if you were ill. With more prolonged sleep deprivation, people report dizziness, tremors, and hallucinations.
immune system
During sleep, a mammals body temperature decreases by 1° or 2°C, enough to save a significant amount of ____.
energy
Also during sleep, ____ activity decreases, saving more energy.
muscle
Animals ____ their sleep duration during food shortages, when energy conservation is especially important.
increase
If one of the main functions of sleep is to shutdown activities at times of relative inefficiency, we might expect to find _________ in species that are equally effective at all times of the day. This appears to be true.
little or no sleep
Another apparent function of sleep is improved ____.
memory
If people learn something and then go to ____, or even take a nap, their memory often improves beyond what it was before the sleep.
sleep
Sleep also helps people ____ their memories: in one study, people who just practised a complex task were more likely to perceive a hidden rule after a period of sleep than after a similar period of wakefulness.
reanalyse
Another study found that a nap that included REM sleep enhanced performance on certain kinds of ____ ____ ____.
creative problem solving
Researchers recorded activity in the ____ during learning, and then recorded the same locations during sleep. Results: patterns that occurred during sleep resembled those that occurred during learning, except that they were more rapid during sleep.
hippocampus
The amount of hippocampal activity during sleep correlated highly with subsequent improvement in ____.
performance
These results suggest that the brain ____ its daily experiences during sleep.
replays
The hippocampus replays recently learned patterns during quiet ____ periods, not just during sleep.
waking
Another aspect of sleeps contribution to memory relates to sleep spindles. They indicate an exchange of information between the ____ and the ____ ____. In both rats and humans, sleep spindles increase in number after new learning.
thalamus : cerebral cortex.
Dream research faces a special problem: what we know that dreams comes from people’s ____, and researchers have no way to check the accuracy of those reports.
self-reports
According to the ____-____ ____, a dream represents the brains efforts to make sense of sparse and distorted information.
activation-synthesis hypothesis
Dreams begin with periodic bursts of spontaneous activity in the ____ – the PGO waves previously described – that activates some parts of the cortex but not others.
pons
The ____ combines this haphazard input with whatever other activity was already occurring and does its best to synthesise a story that makes sense of the information.
cortex
____ ____, such as sounds in the room, occasionally get incorporated into a dream, although usually they do not.
Sensory stimuli
An alternative view of dreams has been labelled the ____ ____ because it was derived from the clinical studies of patients with various kinds of brain damage.
clinicoanatomical hypothesis
Clinicoanatomical hypothesis emphasises that dreams begin with arousing stimuli that are ____ within the brain combined with recent memories and any information the brain is receiving from the senses.
generated
However, the clinico-anatomical hypothesis puts less emphasis on the pons, PGO waves, or REM sleep. It regards dreams as thinking that takes place under unusual conditions, similar to ______ during everyday life.
mind-wondering
Patients with damage to the ____ ____ have problems binding body sensations with vision. They also report no dreams.
parietal cortex
Fairly high activity is also found in the areas of the ____ ____ outside V1. Those areas are presumably important for the visual imagery that accompanies most dreams.
visual cortex
Finally, activity is high in the ____, ____, and other areas important for emotions and motivations.
hypothalamus, amygdala
