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Chapter 5&6

PSYA01H3 Chapter Notes - Chapter 5&6: Conditioned Taste Aversion, Latent Learning, Peyote

Course Code
Steve Joordens

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Chapter 5: Consciousness
Consciousness – a person’s subjective experience of the world and mind.
Circadian Rhythms (PG 182)
- Humans and animals have biological rhythms that are adapted to the cycles in the
oEx: Animals hibernating in the winter
oInfradian rhythms: occur over a period of time longer than a day. (MENSTRUAL CYCLE)
oUltradian rhythms: more frequent biological rhythms. (Heart RATE)
Circadian rhythms are roughly 24 hour cycles in the physiological processes and behavioural
oi.e. the tendency to be asleep or awake at specific times, feel hungrier at certain times, or
even concentrate better at certain times
oOur circadian rhythm are regulated by daylight interacting with our nervous and endocrine
(hormonal) systems
oOne of the key brain structures in this process is the suprachiasmatic nucleus (SCN) of
the hypothalamus.
- Cells in the retina of the eye relay message about light levels in the environment to
the SCN.
- The SCN, then communicates signals about light levels with the pineal gland.
- The pineal gland releases a hormone called melatonin, which peaks in concentration
at nighttime and is reduced during wakefulness.
Light is the primary stimulus regarding the human circadian rhythm
For some people this system is disrupted. Ex: Blind people cannot send light
signals from the retina to the SCN and pineal gland. Therefore, the
circadian rhythms do not synchronize to day-night cycles but can be
adjust by using melatonin doses
oCircadian rhythms adaptation
Entertainment: when biological rhythms become synchronized to external cues
such as light, temperature, or even clock.
Effects on the SCN-melatonin system.
Endogenous Rhythms: biological rhythms that are generated by our body
independent of external cues such as light.
ASCHOFF- underground chambers for four weeks adopting a 25-hour
SIFFRE- remained by himself in a dark cave for two and six months—
concluded that people posses an endogenous circadian rhythm that is 24-25
hour in length.
The Stages of Sleep (PG 183)
Sleep has rhythms
Polysomnography refers to a set of objective measurements used
to examine physiological variables during sleep.
Sleep cycles are defined by the electroencephalogram (EEG), a
device that measures brain waves.
oThe output is a waveform

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Waves can be described by their
Frequency - # up-down cycles every second
Amplitude – Height and depth of the up-down cycle
oBeta waves – high frequency, low-amplitude. They are
characteristic of wakefulness. Their irregular nature reflects the
bursts of activity in different regions of the cortex, and they are often
interpreted as a sign that a person is alert.
oAlpha Waves – As an individual shifts into sleep, the waves become
slower, larger and more predictable. Signal that a person nmay be
daydreaming, meditating, or starting to fall asleep
oEEG signals during
sleep move through four different phases (PG
183- 185)
1. Stage 1: Brain waves slow down and
become higher in amplitude (theta waves).
Breathing, blood pressure, and heart rate all
decrease as an individual begins to sleep.
Lasts about 20 minutes.
2. Stage 2: After 10 to 15 minutes, the sleeper
enters stage 2, during which the brain waves
continue to
slow. Includes
spindles and
k complexes,
which are
periodic bursts of EEG activity. Evidence
suggests these busts may play a role in
helping maintain a state of sleep and in the
process of memory storage. As stage 2
progresses, we respond to fewer and fewer
external stimuli such as lights and sounds.
3. Stage 3: Brain waves continue to slow down and assume a form called delta waves
4. Stage 4: Deepest stage of sleep during which the sleeper will be difficult to awaken.
After an hour after falling asleep, we reach the end of our first stage 4 sleep
phase. At this point, the sleep cycle goes in reverse and we move back toward
stage 1 patterns. We do not go all the way back to stage 1, we move into a unique
stage called REM sleep
5. REM: Last about 10-20 minutes and we have an irregular EEG, increased heart
rate, respiration, bodily movement, rapid eye movement, and brain activity. This
stage is when dreams occur. Time spent in each REM cycle tends to increase
throughout the night. It is also known as paradoxical sleep because the EEG
eaves appear to represent a state of wakefulness even though we are asleep. At the
end of the first REM phase, we cycle back toward deep sleep stages and back
into REM sleep again ever 90-100 minutes.
Critical for a good night’s sleep

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When deprived of sleep, we experience REM rebound, where our brains
spend an increased time in REM-phase sleep when given the chance. Loss
of REM sleep is worse that the amount of sleep lost.
Why do we need sleep? (PG 185-186)
1. Restore and Repair Hypothesis: Idea that the body needs to restore energy levels and repair
any wear and tear on the body from the day’s activities.
oSleep is a physical and psychological necessity
oLack of sleep can lead to cognitive decline, emotional disturbances, and impairs functioning
of the immune system
oThis theory does not account for reason why we sleep
If we have a more active day, we may need more sleep despite what the restore and
repair theory suggest
2. Preserve and Protect Hypothesis: Suggests that two more adaptive functions of sleep are
preserving energy and protecting the organism from harm
oTo support this, researchers note that the animals most vulnerable to predators sleep in
safe places
oThe "Preservation and Protection" theory holds that sleep serves an adaptive function. It
protects the person during that portion of the 24-hour day in which being awake, and hence
roaming around, would place the individual at greatest risk.
oPrimary function of sleep is to conserve energy and protect oneself from predation
There are multiple reasons why we sleep. Research shows it is combination of restoration and repair,
and preservation and protection.
Sleep Deprivation and Sleep Displacement (PG 186-188)
Sleep Deprivation: Occurs when an individual cannot or does not sleep. The result of sleep
deprivation is periods during which the sleep deprivation leads to sleepiness, interspersed with
other periods during which individuals feel perfectly normal levels of wakefulness.
oWhen sleep deprived:
Go through cycles of extreme sleepiness at night with normal levels of wakefulness in the
daytime. As the number of days increases, sleepiness increases and cognitive ability
For every hour of deprivation, predictable increases in physical illness, family problems,
substance abuse, and academic problems occur
Five basic stages of whole sleep cycle
1. Last about 5 min. During this transition stage, brain waves become slower and irregular.
2. Last around 10-20 minutes. Have regular EEG, spindles, and k complexes appear. Less than 50%
of sleep is spent here.
3. Brain waves continue to slow down and assume the form of delta waves. Short transition phase of
slow wave sleep made up 20-50% delta waves.
4. Run 15-30 minutes. In this stage, we have less the 50% of delta waves. Represents deep
restorative sleep. We spend about 30 minutes here the first time we cycle through it with less
time spent here as night progresses.
Then we cycle back into stage 3 and 2 before entering stage 5.
5. REM. Last about 10-20 minutes and we have an irregular EEG, increased heart rate, respiration,
and brain activity. This stage is when dreams occur. Time spent in each REM cycle tends to
increase throughout the night.
Then we cycle through 2, 3,4 and we repeat the 90-minute cycle about 5 times in the night.
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