December 9th, 2014
CS 110-1
Valeria Muzzin
DREAMS
Valeria Muzzin
Project
CS 110-1
INDEX
Dreaming and the Brain ................................ 3
How do dreams occur? .................................4
Freud’s view of dreams ................................ 6
Dream Contents ............................................ 7
Primitive Instinct Rehearsal Theory .............. 8
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Dreaming and the Brain
When we sleep, we go through five sleep stages. The first stage is a very light sleep from which it is easy
to wake up. The second stage moves into a slightly deeper sleep, and stages three and four represent
our deepest sleep. Our brain activity throughout these stages is gradually slowing down so that by deep
sleep, we experience nothing but delta brain waves -- the slowest brain waves. About 90 minutes after
we go to sleep and after the fourth sleep stage, we begin REM sleep.
During REM sleep, several physiological changes
also take place. The heart rate and breathing
quickens, the blood pressure rises, we can't
regulate our body temperature as well and our
brain activity increases to the same level (alpha)
as when we are awake, or even higher. The rest
of the body, however, is essentially paralyzed
until we leave REM sleep. This paralysis is caused
by the release of glycine, an amino acid, from the
brain stem onto the moto-neurons (neurons that
conduct impulses outward from the brain or
spinal cord). Because REM sleep is the sleep stage
at which most dreaming takes place, this paralysis
could be nature's way of making sure we don't
act out our dreams. Otherwise, if you're sleeping
next to someone who is dreaming about playing
kickball, you might get kicked repeatedly while
you sleep.
Rapid eye movement (REM) was discovered in
1953 by University of Chicago researchers
Eugene Aserinsky, a graduate student in
physiology, and Nathaniel Kleitman, Ph.D., chair
of physiology. REM sleep is primarily
characterized by movements of the eyes and is
the fifth stage of sleep.
The four stages outside of REM sleep are called
non-REM sleep (NREM). Although most dreams
do take place during REM sleep, more recent
research has shown that dreams can occur
during any of the sleep stages. Tore A. Nielsen,
Ph.D., of the Dream and Nightmare Laboratory
in Montreal, refers to this as "covert REM sleep"
making an appearance during NREM sleep.
Most NREM dreams, however, don't have the
intensity of REM dreams.
Throughout the night, we go through these five stages several times. Each subsequent cycle, however,
includes more REM sleep and less deep sleep (stage three and four). By morning, we're having almost
all stage one, two and five (REM) sleep.
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How do dreams occur?
Despite years of research, the neurological basis for dreams is still not entirely certain, and several
theories (including the activation synthesis theory, the long-term memory excitation theory, the
continual-activation theory, and others) have been proposed for how and why dreams occur at all,
none of which are entirely satisfactory or universally accepted.
The
activation-synthesis
model, proposed by J. Allan
Hobson and Robert Mc Clarley
back in the 1970s, suggests
that, as circuits in the brain
become activated during REM
sleep, areas of the limbic
system including the amygdala
and hippocampus (the parts of
the brain involved in emotions,
sensations and memories) also
becomes active. The brain
synthesizes and subjectively
interprets this internal activity,
and attempts to find meaning
in the random signals, the
results of which are what we
call dreams.
Eugen Tarnow developed his longterm memory excitation theory in
2003, arguing that dreams are just
the brain’s internal excitations of
long-term memories. This theory
holds that such excitations are
going on all the time, even during
our waking hours, but the “reality
checking” of the brain's executive
function (which takes place in the
prefrontal cortex, and which is
known to be actively suppressed
during sleep) usually excludes them
from our notice. In some ways, this
is consistent with many of Freud’s
psychoanalytical
ideas
about
dreams, with Freud’s unconscious
replaced by our long-term memory.
But whatever the underlying reasons for why dreams arise, the
physiological and neurological mechanisms underpinning the act of
dreaming are, while still not entirely understood, gradually beginning to
become clearer as modern research progresses.
In 2004, Jie Zhang
developed the continualactivation
theory
of
dreams, which argues that
dreams are part of the
brain’s consolidation of
working memories into
long-term
memories
(declarative
memories
during non-REM sleep,
and procedural memories
during REM sleep). Zhang
believes that both the
conscious
and
nonconscious
subsidiary
systems
of
working
memory need to be
continually activated in
order to maintain proper
brain functioning and,
when the level of
activation
of
either
subsidiary system falls
below a given threshold,
the brain automatically
triggers the generation of
a data stream from its
memory stores. Dreaming
is therefore merely an
incidental result of the
brain's need for continual
activation.
The activation-synthesis
model is just one of
several theories as to how
and why dreams occur
(image from Prentice Hall:
Invitation to Psychology)
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Recent studies have highlighted two specific areas of
the brain in which the absence of activity seems to
cause the loss of the subjective experience of
dreaming: one, where the occipital, temporal and
parietal lobes of the cerebral cortex meet; the other,
in the frontal cortex, specifically in parts where
dopamine is the dominant neurotransmitter. These
areas, it should be noted, are completely unconnected
to the areas of the brain involved in generating REM
sleep, which is mainly regulated in the pons area of
the brainstem. REM sleep and dreaming can, then, be
completely dissociated from one another, as certain
cases of brain damage and drug administration have
proven, and it is becoming clear that REM sleep may
be just one of the triggers for dreaming.
During REM sleep, the limbic system of the brain,
including the hippocampus and amygdala (which are
involved in processing emotions and motivation,
among other things) is very active, while some areas
of the prefrontal cortex (which are involved in working
memory and attention, but also logical reasoning and
self-control) are notably inactive. This is consistent
with some of the bizarre, illogical and disorganized
imagery in dreams, as well as the absence of logic and
self-criticism which often characterizes them. During
dreams, then, the brain allows its most recentlyevolved, more controlling side (the prefrontal cortex)
to give way to a more primitive, less rational way of
thinking (under the influence of the amygdala and the
limbic system.
).
Some researchers have even proposed the radical
theory that we do not dream throughout REM sleep at
all, because we do not have the consciousness
necessary to generate dreams during this time.
Instead, they argue that our dreams are actually
constructed (from subliminal images generated while
we are asleep) during the few hundredths of a second
in which we are waking up. Dreams may also be
generated in the same way during the several “microawakenings” we all experience throughout our sleep
periods (even though we are rarely consciously aware
of them), especially before, during and after periods of
REM sleep. According to this theory, dreams represent
the conscious expression, during awakening, of the
unconscious brain activity that occurs while we are
asleep.
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Damage to the parietal lobe of the brain, for
example after a stroke, can lead to a complete
absence of dreams. Because the parietal lobe
is responsible for bringing together all the
different senses, it is hypothesized that the
imaginary space in which our dreams take
place is generated in that part of the brain.
People who have damaged parietal lobes can
usually fall asleep easily enough, but tend to
wake regularly throughout the night, almost as
though they wake whenever they would
normally have experienced a dream.
The neurotransmitter-dopamine appears to be
an important factor in dreaming, and people
who take medications to reduce their
dopamine levels tend to dream noticeably less,
while those (such as Parkinson’s Disease
sufferers) who take medications to increase
their dopamine levels tend to dream more
intensely, even though the frequency and
duration of their REM sleep may be
unchanged.
The limbic system is a relatively primitive part
of the human brain, where emotions,
memories, etc, are processed.
Although the primary visual cortex is almost completely inactive during REM sleep (as might be expected
when there are no external visual signals coming in), the extra striate visual areas of the cortex (which are
involved with analyzing complex visual scenes) are highly active, which is consistent with the elaborate
internal visual images in dreams.
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Freud’s view of dreams
In the late 19th century, psychotherapist Sigmund Freud developed a theory that the content of
dreams is driven by unconscious wish fulfillment.
Freud called dreams the "royal road to the unconscious." He
theorized that the content of dreams reflects the dreamer's
unconscious mind and specifically that dream content is shaped
by unconscious wish fulfillment. He argued that important
unconscious desires often relate to early childhood memories and
experiences. Freud's theory describes dreams as having
both manifest and latent content. Latent content relates to deep
unconscious wishes or fantasies while manifest content is
superficial and meaningless. Manifest content often masks or
obscures latent content.
In his early work, Freud argued that the vast majority of latent
dream content is sexual in nature, but he later moved away from
this categorical position. In Beyond the Pleasure Principle he
considered how trauma or aggression could influence dream
content. He also discussed supernatural origins in Dreams and
Occultism, a lecture published in New Introductory Lectures on
Psychoanalysis.
Freud believed that the function of dreams is to preserve sleep by
representing as fulfilled wishes that would otherwise awaken the
dreamer.
In Freud's theory dreams are instigated by the daily occurrences
and thoughts of everyday life. His claim that they function as wish
fulfillments is based on an account of the “dream work” in terms
of a transformation of "secondary process" thought, governed by
the rules of language and the reality principle, into the "primary
process" of unconscious thought governed by the pleasure
principle, wish gratification and the repressed sexual scenarios of
childhood.
In order to preserve sleep the dream work disguises the
repressed or “latent” content of the dream in an interplay of
words and images which Freud describes in terms of
condensation, displacement and distortion. This produces the
"manifest content" of the dream as recounted in the dream
narrative. For Freud an unpleasant manifest content may still
represent the fulfilment of a wish on the level of the latent
content. In the clinical setting Freud encouraged free association
to the dream's manifest content in order to facilitate access to its
latent content. Freud believed interpreting dreams in this way
could provide important insights into the formation of neurotic
symptoms and contribute to the mitigation of their pathological
effects.
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Born
Died
Nationality
Fields
Sigismund
Schlomo Freud;
6 May 1856;
Freiberg in
Mähren,
Moravia,
Austrian
Empire
(now Příbor,
Czech
Republic)
23 September
1939 (aged 83)
London,
England
Austrian
Neurology;
Psychotherapy;
Psychoanalysis;
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Dream Contents
From the 1940s to 1985, Calvin S. Hall collected more than 50,000 dream reports at Western Reserve
University. In 1966 Hall and Van De Castle published The Content Analysis of Dreams, in which they
outlined a coding system to study 1,000 dream reports from college students. Results indicated that
participants from varying parts of the world demonstrated similarity in their dream content. Hall's
complete dream reports became publicly available in the mid-1990s by Hall's protégé William Domhoff,
allowing further different analysis.
VISUAL
EMOTIONS
The visual nature of dreams is generally highly
phantasmagoric; that is, different locations and
objects continuously blend into each other. The
visuals (including locations, characters/people,
and objects/artifacts) are generally reflective of
a person's memories and experiences, but
banter can take on highly exaggerated and
bizarre forms.
People who are blind from birth do not have
visual dreams. Their dream contents are related
to other senses like auditory, touch, smell and
taste, whichever are present since birth.
In the Hall study, the most common emotion
experienced in dreams was anxiety. Other
emotions included abandonment, anger, fear,
joy, and happiness. Negative emotions were
much more common than positive ones.
SEXUALITY
COLOR VS. BLACK & WHITE
The Hall data analysis shows that sexual dreams
occur no more than 10% of the time and are
more prevalent in young to mid-teens. Another
study showed that 8% of both men and
women's dreams have sexual content. In some
cases, sexual dreams may result in orgasms or
nocturnal emissions. These are colloquially
known as wet dreams.
A small minority of people say that they dream
only in black and white. A 2008 study by a
researcher at the University of Dundee found
that people who were only exposed to black
and white television and film in childhood
reported dreaming in black and white about
25% of the time.
RELATIONSHIP WITH MEDICAL CONDITIONS
There is evidence that certain medical conditions (normally only neurological conditions) can impact
dreams. For instance, some people with synesthesia have never reported entirely black-and-white
dreaming, and often have a difficult time imagining the idea of dreaming in only black and white.
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Primitive Instinct Rehearsal Dream Theory
Two
researchers
have
postulated that dreams have a
biological function, where the
content requires no analysis
or interpretation, that content
providing
an
automatic
stimulation of the body's
physiological
functions
underpinning the human
instinctive
behavior.
So
dreams are part of the human,
and animal, survival and
development
strategy.
Professor Antti Revonsuo
(2000) has limited his ideas to
those of "threat rehearsal,"
where dreams exercise our
primary self-defense instincts,
and he has argued this
cogently in a number of
publications.
Keith Stevens extends the
theory to all human instincts,
including threats to self,
threats to family members,
pair
bonding
and
reproduction, inquisitiveness
and challenges, and the drive
for personal superiority and
tribal status. He categorizes
dreams, using a sample of
22,000 Internet submissions,
into
nine
categories,
demonstrating the universal
commonality
of
dream
content and instinct rehearsal.
It is postulated that the dream
function is automatic, in
response to the content,
exercising and stimulating the
body
chemistry
and
neurological activity that
would come into play if the
scenario occurred in real life,
so that the dream does not
have to be remembered to
achieve its objective.
For human reproduction, the theory states that
dreams of pairing, bonding and mating stimulate
the reflex to reproduce the species, with an
emphasis on dreams that promote the principle
of selection; the desire of the individual to find
the best mate and to achieve the optimum
genetic mixing. In that respect, the dream
function conflicts with human values of fidelity
and mating for life. Specifically, young women
dream often of being pregnant and giving birth,
overwhelmingly positive dreams that directly
stimulate the urge to reproduce.
It is argued that, once a
dreamer has experienced a
threat in a dream (either to
self or a family member),
his/her ability to confront and
overcome a real life threat is
then enhanced, so that such
dreams, in both humans or
animals, are an aid to survival.
The threat rehearsal can be
specific, for instance, an
attack from a savage dog, but
it can also be general, and in
that the threat response
physiology is activated and
reinforced whilst dreaming.
Regarding status, dreams about being superior
or inferior to others are thought to stimulate
the dreamer's determination to improve his
status within the immediate human hierarchy,
either through the positive physiology of
success or the negative physiology of failure.
Hence, dreaming is believed to promote
competition and the reproductive success of
those best suited to the environment.
Finally, other dreams stimulate the determination to explore and inquire, through the extremes of
exhilarating dream achievements (positive physiology) or frustrating obstructions and barriers. The
latter stimulates a determination not to give up in a quest, so that, in life, the individual and the species
move forward. For the dreaming wildebeest, it may be a rich pasture over the hill; for the human
dreamer it may be splitting the atom.
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Valeria Muzzin
Project
CS 110-1
LINKS
Power Point Document
DREAMS.pptx
tExcell Document
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