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Biology 202, Spring 2005
Third Web Papers
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The Functional Role of Dreaming

Alfredo Sklar

Each night we lay in our beds after a hard day's work eager to get some much needed rest and to let our brains take over as we become an audience for our forebrain. We usually wake up the next morning either marveling at or terrified of the bizarre and uncanny, yet intriguing dream we just experienced. We wonder how our brains could have produced such complex storylines without any conscious effort on our part and are infatuated with unlocking their true meaning. It then becomes easy to understand why so many people, dating all the way back to Aristotle, have devoted so much time and energy to understanding the mechanisms of how dreams are generated and what purpose they serve. As a result, there is an astounding range in the variety of theories for this topic, especially since the discovery of REM sleep and the other sleep cycles in the 1950's. This paper will survey a few of these major theories about the function of dreams in a more or less chronological fashion starting with the psychoanalytic perspective presented by Sigmund Freud.

Freud's wish fulfillment theory of dreams is closely tied to his other work on the subconscious and the intrapersonal dynamics among the id, ego, and superego. He believes that the wish impetus (sexual desires, deeply rooted emotional feelings, etc.), which is controlled by the subconscious, is manifested during our sleep through dreams (1) . The subconscious and its wishes are suppressed throughout the day, as they are seen as socially unacceptable by our superego and the rest of our conscious, and uses dreams as an escape from the stranglehold of the conscious which is not at work during sleep (1). Based on this notion, Freud believed that through a careful interpretation of a dream one can uncover the deeply repressed thoughts and feelings that are causing distress and even mania in an individual.

Freud carried out his analysis by dividing the dream into to parts: its latent content and its manifest content. In this model of the dream, the manifest content can be thought of as the plot or storyline of the dream (2). Freud suggested that this aspect of the dream is used merely as a disguise for the true, underlying meaning/wish that the dream is trying to convey and therefore relatively unimportant to the psychoanalysis of the patient (2). In contrast, he believed the latent content is where the wish impetus lies and is the aspect of the dream that can lead to one's coming to terms with their id (their subconscious) and its desires. Freud called the process by which the latent content is transformed and disguised by the manifest content the "dream work" and believed that it occurred in four different ways: condensation (the combining of two ideas present in the latent content), displacement (of the desires of the latent content from its intended target to a random object/person), symbolism (the use of images in the dream to represent repressed thoughts/feelings), and secondary revision (the process by which we try to make sense of the dream, usually the morning after, and put it into an everyday context) (2). Through the dream work and its processes, Freud was able to explain why dreams seem so bizarre and disjointed.

The neurobiological perspective on dreaming then rose to dominance after the discovery of REM sleep by Aserinsky and Kleitman in 1953 (3). This is also known as paradoxical sleep because although our bodies are momentarily paralyzed and in a state of deep sleep, our brain shows activity similar to that of waking consciousness. The brain of someone in the REM phase of sleep will display random patterns of cortical activity and single-phase waves (POG waves) can be observed in the visual cortex (3). Dreamers experiencing REM will also exhibit regular patterns of rapid eye movements (from which this sleep phase gets its name). As a continuation of these findings, Hobson and MacCarley came out with a theory which they thought would render Freud's theories completely useless. In their activation-synthesis hypothesis they contend that the POG waves observed during REM stimulate higher forebrain cortical areas causing rapid eye movements and activating parts of the association cortex (3). It is then believed that the forebrain, in an attempt to make sense of the random waves of brain activity, produces an equally random storyline to go along with it. Therefore, Hobson and MacCarley believe that there is no deeper meaning or symbolism to a dream as it is a product of random brain activity and not of any cognitive function. As a result, clinical analysis and introspection should only be done on the patient's reaction to the dream and how they deal with the ideas presented by it (3).

The activation-synthesis hypothesis, however, did not completely disprove Freud's work as Hobson and MacCarley had though and was met by quite a bit of criticism and questioning. Probably the major blow to this theory was dreams can occur during non-REM sleep and that visual activation is still experienced even without the random bursts of POG waves (4). Most of the other controversy stirred up by the activation-synthesis hypothesis came from other dream researchers who believed that this theory did not give enough of a role to higher brain functions (4). They believe that the fact that dreams can sometimes be so coherent and provoke such strong and interesting personal thoughts proves that the cortex and higher brain areas must play a more serious role in the generation of dreams. As an example, opponents of this theory often times point to lucid dreaming where the individual can exhibit some control over their dreams to refute the idea that dreams are created randomly and cannot be used to reveal deeply repressed emotions and desires (4).

Recently there has been a rise in the cognitive perspective on dreams which concentrates on the reason/purpose for dreams and REM sleep rather than what they can tell us or how they occur. Researchers in this field view dreams as an integral part of the memory formation and learning processes (5). This idea has been supported by various studies done on the role of REM sleep on memory and learning. For example, it has been shown by Smith that the learning of procedural information is significantly impaired by a decrease in REM sleep. And along the same lines, LaBerge showed that the learning of difficult tasks requiring concentration and often times newly acquired skills is followed by an increase in the amount of dreams experienced during sleep and the duration of the REM phase in the sleep cycle (5).

One of the possible mechanisms by which our brains process the days information through the use of REM sleep and dreams was proposed by Evans in his book "Landscapes of the night: How & Why we dream" (6). In this book Evans presented his view of the brain as a computer. He believes that during REM sleep, the brain is taken "offline", blocking it from all external stimulus while it scans over the experience we had throughout the day, making any necessary modifications to it (6). This process is thought to aid in the transfer of information from short-term to long-term memory (5). During this process, the brain may briefly come back "online", allowing the conscious mind to view clips of this stream of consciousness that is being replayed (6). This is what Evans believes a dream to be.

The last theory on the function of dreams that we will review is the one presented by many developmental psychologists interested in dream research. It has been shown that for new born babies, REM sleep makes up a much larger proportion of the sleep cycle than for adults (about 50% of their sleep cycle is REM) (7). The question then becomes: why do infants require so much more REM sleep than adults? The answer developmental psychologists will have you believe is that dreams and REM sleep play an important part in the development of the infant brain (7). Newborns, although born with a complete nervous system, have not had the time to develop proper neural connections or mature synapses. The neural activity generated by REM sleep and necessary for the production of dreams helps to develop these neural pathways (7). This sort of development is obviously not necessary for adults as a lifetime of consciousness and experience has taken care of it.

As we can see from the above examples, there is still much disagreement and controversy over what the true function of dreams is. However, it is unlikely that there is one, absolutely correct theory on dreams (or one that is the least wrong). The best way to think of the role and causes of dreams is through a synthesis of a few of the best theories. For example, for the experiments done by Hobson and MacCarley we know that the random discharge of brain waves from the brain stem probably plays a big part in the generation of dreams rather than the wishes of our subconscious. However, it is unreasonable to think that our internal state (thoughts and emotions) do not influence and, to an extent, dictate what happens in our dreams. I believe that the future of dream research lies in this type of cooperative effort from researchers in the different fields of study involved.









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