PSYC 110 Lecture Notes - Lecture 12: Prefrontal Cortex, Optic Chiasm, Reticular Formation
27 Jun 2018
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Doggie Narcolepsy - Dog has a constant urge to sleep, cannot stay up
Sleep acts as a regulatory drive - just like hunger, thirst - you get an indication when you are deprived of
it and you act upon it. The longer you go without it, the more it will creep up on you and increase your
urge. Animals too, engage in sleep. Why do humans take 1/3rd of the day to engage in sleep?
What is sleep?
Condition of relative unresponsiveness to the environment. It is a period of rest and restoration for the
body and mind. You feel energized and rested. The body is passive, dormant, but the mind is quite
active. Neuroimaging evidence shows that even when the body is passive, the mind is doing a lot. Your
mind can sometimes be more active than the body. Sleep is an essential bodily function. If you don't
sleep, you will die. Hunger and thirst regulates to put things in your body but sleep does not regulate to
provide anything except complete the urge.
How do we study sleep?
EEG, non-invasive technique for measuring neural activity. It has developed through the years. The
electrodes take brain waves and put it into proportion to make one pattern. The brain goes through
different cycles such as when you are awake, the brain makes beta waves. They are sporadic and
associated with your mind being awake and working. When you shut your eyes and relax, there are
alpha waves. When you are falling asleep into stage 1, small irregular waves. Deeper sleep or stage 2 has
sleep spindles. And if we go into deeper sleep into stage 3, delta waves appear, larger sweeping with
greater wavelengths. Stage 4 is the deepest sleep where you are the most unresponsive, again delta
waves but they appear very oscillating.
From stage 4, you come back to stage 1 and it is called REM. You cycle through this about 4 times every
night - REM sleep is called emergent stage because it marks the onset of a new cycle.
Sleep is categorized as:
Non-Rapid Eye Movement (NREM) - includes stage 1,2,3,4
Rapid Eye Movement (REM) - Period of the night where your muscles lock up and you become
paralyzed. Sleep paralysis - you are in REM sleep but your body is awake. Eyes twitching, brain becomes
active, muscles are locked up. Typically the time when we dream. Most dreams happen in REM (not all).
You dream about 90 mins after you sleep and about 4-6 times a night. Often, we forget our dreams but
remember some details of it. Why? Your brain activates these waves that produce visual cortex and
attach them to external sensory areas. Amygdala is being stimulated. They could be representations of
things that have been happening around you or your suppressed desires. You remember emotionally
heavier dreams than benign dreams.
Psychoanalytic: dreams are an opportunity to work through feels and drives that aren't
consciously expressed.
Information processing: dreams are an opportunity to process and consider information from
the previous day
Threat stimulation: brain gets practice handling threatening situations
True dream - dream that appears as a real event - more the time spent in REM sleep, the more real the
dream feels. Mental activity in non REM sleep appears as sleep thought. Sleeping person's brain sorts
out sounds by meaning - parents wake up to child crying but not to a thunderstorm.
What is the function of Sleep?
Preservation and Protection Theory: Animals need only a certain amount of time in the day to
do what they need to do to survive. For example, to pick up berries or get food it might take 4
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Document Summary
Doggie narcolepsy - dog has a constant urge to sleep, cannot stay up. Sleep acts as a regulatory drive - just like hunger, thirst - you get an indication when you are deprived of it and you act upon it. The longer you go without it, the more it will creep up on you and increase your urge. It is a period of rest and restoration for the body and mind. The body is passive, dormant, but the mind is quite active. Neuroimaging evidence shows that even when the body is passive, the mind is doing a lot. Your mind can sometimes be more active than the body. Hunger and thirst regulates to put things in your body but sleep does not regulate to provide anything except complete the urge. The electrodes take brain waves and put it into proportion to make one pattern.
