REM
Sleep
In 1953 neurobiology conquered
dream research. The discovery of REM sleep - a certain
phase of sleep named for the dreamer's rapid eye
movements - marked the beginning of a new era in the
study of dreams (and sleep). The emphasis on physiology
gave rise to new ideas about dreams, the most radical of
which consider dreams to be mere trash cans for our
sleeping brains.
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 to reuse it or rewinds a VCR tape to record the
latest Seinfeld.
Not quite brain garbage, yet
still randomized products created by uncontrolled
fireworks of nerve cells in our sleeping brain - that is
how J. Allan Hobson, a Harvard psychiatrist and
neurophysiologist, describes dreams. In his view, dreams
come into being when these random signals reach the
cortex, the brain's center of thinking and reasoning,
which tries hard to make sense of the arbitrary inputs.
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.
However, the great majority of
the dreams Domhoff analyzed contain familiar settings and
known characters that take part in recognizable, and
reasonable, activities. "Dreams are, in fact, generally
well-organized and lack bizarre elements," agrees David
Foulkes, a professor Emeritus of psychology at Emory
University in Atlanta.
Nor can dreams simply be equated
with REM sleep, which is what both Crick and Hobson focus
on, Domhoff says. The equation between REM sleep and
dreams was the prevailing credo among dream/sleep
researchers in the late 1950s and early 1960s. For the
first time, psychologists could trace a mental process -
dreams - to a physiological activity - REM sleep. "It was
a very exciting time and an exploding field. We were the
hot guys on the block - even newspapers wanted to talk to
us," Domhoff remembers. But the simple equation did not
stand the test of time. The longer psychologists studied
sleeping subjects, the more it became obvious that
dreaming occurs in all other phases of sleep, Domhoff
says.
Domhoff and Foulkes are
particularly aggravated by neuroscientific attempts to
explain the nature of dreams by reducing them to some
physiological phenomena, such as the measurement of brain
activities. Says Foulkes, "No PET scan, or any other
fancy biotechnical doodad, is capable of observing or
characterizing the nature of dreaming." They refer to
such approaches as "biologic reductionism."
"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.
"
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