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Biology 202, Spring 2005
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A Neurobiology of Dreaming: Dreams and Biologic Reductionism


Elizabeth Diamond

Dreaming is one of the brain’s more perplexing and fascinating phenomena. Sometimes
vivid, colorful and bizarre, other times simply odd or mundane, dreams create an entirely
different world for the sleeper out of often-random images, sounds or other sensations.
But how can it be explained? Is there a “dream center” in the brain that is activated
during sleep, or is there a change in brain chemistry during REM sleep that brings about
these nightly visions? Several neurobiological factors contribute to dreaming, and this
paper asserts that dreams can be explained through said biological processes alone, and
that to dream is no different from performing any other waking function, a hypothesis
that is rather pejoratively referred to as “biologic reductionism.” The term in this paper, however, is not used so negatively, but rather is used to support the working model of brain=behavior in our class lectures.

To start off, people have always wondered whether or not there is a function or
evolutionary advantage to dreaming. If so, what would this function be? Some
researchers are fond of comparing the brain’s sleeping processes to that of defragmenting
a computer: “For Nobel laureate Francis Crick of the Salk Institute in San Diego, dreams
are nothing but random attempts, without any deeper meaning, to clear from the brain
unneeded or even harmful memory. Crick claims this is a necessary step to reset the brain
for the next day, much as one erases old data from a floppy disc” (1). Others, such as
psychologist J. Allan Hobson, proposed that dreams are the result of random impulses in
sleeping neurons of the brain, and that dreams arise from the brain’s attempt to make
sense of these spontaneous neural impulses. (1)

However, current research suggests that dreaming serves neither a discernible biological
purpose, nor do dreams result from random firing patterns. Rather, dreams are simply a
form of “sleep thinking,” a good example of nerves firing on their own in the brain and
creating their own signals"the autonomous function of what we refer to in class as the
individual “boxes” within the brain. These firing patterns of the neurons are far from
random; psychologist Bill Domhoff’s work in studies of sleep and dreaming would
indicate a very organized network of brain structures that continue to function during
sleep in very much the same way they function in our waking hours.

What is interesting to consider is not why, but how we dream. The ability to dream in an
organized, almost story-like progression arises from what psychologist Bill Domhoff
calls a human “cognitive achievement.” As far as we know, animals do not dream, at
least in the same story-line format that humans are able to create. Neither do very young human children; in lab settings, children under the age of 9 reported mostly static images or feelings whenever awakened during an REM dreaming episode. Older children
seemed to develop the ability for story dreams, that is, a dynamic situation within the
dream that reflected certain activities or emotions (4). These studies performed by
Domhoff and David Foulkes bring up the idea of the “cognitive achievement principle,”
that is, certain neural networks in the forebrain (particularly parietal) areas must be well established before vivid, story-like dreaming can occur (4). In children under the age of 9, these areas of the brain are not yet as complexly developed as in the older children who more frequently report the story dreams.

A second question that has also fascinated researchers: do dreams have meaning or a
universal symbolism as described by such analysts as Carl Jung? According to Dumhoff,
they do not; dreams are simply a reflection of everyday occurrences or going through
familiar tasks. This is what Domhoff refers to as the “cognitive continuity principle,” (4) or the fact that experiences and emotions that occur during waking hours are very much active during sleep as well. Often, though certain objects in a dream may seem out of place or from another situation altogether, the brain will put these elements together and work them into the typical story-dream format that, surprising and bizarre as the dream may seem, actually makes sense in terms of a story progression. The supposed
phenomenon of dreaming as a problem-solving device works similarly, but it must be
stressed that the dream itself does not offer a some solution outside of our knowledge to
problems mulled over during the day. Whether or not a possible solution arises from
later consideration of the dream is one thing, but dreaming is not problem-solving: a
dream may serve as an inspirational tool to artists, for example, but in fact a dream more often than not reflects the waking worries of the person (2). This is a prime example of Domhoff’s third principle, the “repetition principle” (4) which states that we cannot dream of what we do not know, and that what we do dream is largely made up of familiar activities, situations, and fears we experience in everyday life. But again, without the complex network of brain structures in the parietal lobes, the brain would most likely lose this ability to create a cogent dreaming situation from our experiences, further stressing the importance of biological mechanics in dreaming.

Another piece of evidence in favor of biologic reductionism is the study of REM sleep:
Studying the physiology of the sleeping brain reveals a different brain chemistry during
sleep, according to the “random firings” hypothesis proposed by neurophysiologist J.
Allan Hobson: “Random firings, Hobson says, are due to a very different composition of
signal-transmitting chemicals, called neurotransmitters, in the brain during REM sleep as
compared to the waking brain. According to Hobson, a different brain chemistry also
explains"through chaotic nerve impulses"our wild and bizarre dreamscapes during
REM sleep” (1).

But the idea of chaotic randomness goes against Domhoff’s view of higher-order
processes, such as the continuity and cognitive achievements that allow for organized
story-dreaming. If the signals were simply random and uncoordinated, the things we
dream about would not be integrated into any recognizable form at all, and sleepers
would report the static dream images or feelings as witnessed in patients with damage to
critical structures of the brain. Therefore, these higher processes cannot, and should not, be thought of as a process that occurs outside of neurology. Important structures in the limbic system, parietal and occipital lobes have been shown to play important roles in the story-format of dreams. Dreaming should not be interpreted as anything more
meaningful or mystical than waking thoughts, which admittedly can often be as strange
as any dream fragment. The important thing to remember, though, is that changes in the
brain lead to changes in dreaming; brain damage, drugs, or disruptions of neural networks
have all been shown to have an effect on the nature of a person’s dreams (4), a strong
argument for the neurobiological basis of dreaming. Although sometimes it may seem
that a certain “prop” or object in a dream is put there to represent something more
significant or is the product of the subconscious, this cannot be the case according to so called “biologic reductionism,” or the idea that dreams can be explained solely through the firing patterns of neurons. Yet Domhoff and Foulkes are themselves wary of biologic reductionism’s attempts to explain the nature of dreaming through simple measurements of brain activities: “‘I am always very wary about neurobiological findings. Dreams are not just eye movements,” Domhoff says. ‘There might be a neurobiology of dreaming, but never a neurobiology of dreams’” (1).

Domhoff is right when he says dreams are not simply “eye movements;” REM sleep is
merely characterized by such eye movement and does not even always indicate a dream:
dreaming can also occur in other deep stages of sleep (3). Yet why should dreaming be anything governed by principles outside of the brain? Even with all the accumulated evidence for a relatively simple explanation of how we dream, researchers are still wary of tackling the question of why we do it. If there is no greater significance in dreaming other than “thinking while we sleep,” why do we want to believe in a greater meaning for our dreams? Why should our brains create a sleeping reality impossible to explain through the normal firing patterns of “waking” neurons? After all, no one believes that waking thoughts are so unusual, no matter how off-the-wall any one fleeting thought may be. Why then, should dreams hold such a mystic quality if they are nothing more than a sleeping biological process?

References


1)Science Notes, 1998, A site summarizing the work of noted psychologists and neurophysiologists in the field of dream research

2)Domhoff, G. W. (2003). The Case Against the Problem-Solving Theory of Dreaming., A paper refuting the so-called "problem solving" method of dreams.

3)The Purpose of Dreams, a short paper on dreaming's function and meanings in society.

4) Domhoff, G. W. (2001). A new neurocognitive theory of dreams. Dreaming, 11, 13-
33.

5)The Quantitative Study of Dreams, A comprehensive database of dream studies, researchers and published papers.


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