Reasons To Dream
Science stirs anew over
whether dreaming serves a function.
By Jack Lucentini
August 14, 2001
WHEN RESEARCHERS early this year announced they had strong evidence
their laboratory rats dreamed of navigating mazes, it was widely
seen as a
dramatic confirmation of what many researchers had thought:
that dreams aid
in memory and learning.
The Massachusetts Institute of Technology findings, showing that the
sleeping animals apparently reviewed their waking experiences in the
were also striking for their use of the newest brain monitoring
Researchers believe they can now "read" some thoughts, in
a crude sense, by
recording brain cells' electrical activity.
But the findings in no way settled a long-standing debate among
about what functions dreams may serve. Rather, the research
to a field of research that, its participants say, is
revitalization and a small revolution.
"There really has been an enormous renaissance in dream science," said
Solms, a psychoanalyst with Royal London Hospital and author of
books and papers on dreaming. "Suddenly everyone wants to do
this area, because the questions are much more interesting
than they were
five years ago."
In those five years researchers have hacked away at established
dreams. Psychiatrists have shown renewed interest in them
as a subject for
therapy. And detailed computer images showing how the
sleeping brain works
have become widely available, propelling the rest
of the research.
That work, in particular, "is going very fast," said Rosalind
chairwoman of the psychology department of
Medical Center in Chicago. "We've been
better able to tie together the
anatomy and the creative functions of
These studies show that during the phase of sleep most closely
with dreaming, brain regions responsible for emotion,
memory and fear are a
flurry of activity. Other brain areas - notably
the logic department - seem
to excuse themselves from the party.
But that leaves many questions. Do dreams have some use? Why are we
always duped into believing we're awake? How do we come up with
dreams in the first place?
Debate over these questions boiled over into what some researchers call
small revolt in the past four years-another reason they say the
A theory that has held sway since the late 1970s suggests dreams are
random, meaningless brain activity. That idea convinced many
research has little use, and triggered a sharp drop in
private funding for the work, Cartwright said.
"It really killed the field," she said.
This is changing, she added: Researchers have successfully challenged
in the past four years, giving a lift to scientists who propose
of functions for dreaming.
Theories to explain dreams are all over the map. The scientific journal
Behavioral and Brain Sciences has reported on these theories: that
are an evolutionary adaptation for rehearsing threatening
they were originally a form of waking thought in
lower animals; and, a bit
more blandly, that they just help us wake
But a handful of supposed functions for dreams seems particularly
among researchers, including the claim that dreams aid in
or creative problem-solving. Examples abound:
According to sleep
researchers, golfer Jack Nicklaus claimed his game
improved after he
dreamed a new way to grasp the club.
Another of the more popular theories is that dreams help process
memories. That is, they help us deal with emotional problems
them into our network of memories, comparing them with
problems and, perhaps, looking for solutions.
According to Yale University's Dr. Morton F. Reiser, the latest
supports this view. This is why "the dream in psychiatry is
a more interesting and prominent position," Reiser
wrote in an article in
the March issue of the American Journal of
None of the questions is likely to reach any conclusion before a hard
scientific debate is settled over how our brain circuitry generates
dreaming. The outlines of this puzzle are falling into place, but
To understand this, it helps to start with a little history.
Modern dream research started a century ago with the father of modern
psychology, Sigmund Freud. Freud said every dream metaphorically
an unfulfilled wish, rooted in unresolved childhood traumas
dreamer has pushed out of his or her waking consciousness.
A therapist's job, Freud said, is to extract the truth about these
to help patients confront them head-on.
Freud's view was established currency among psychiatrists by the 1950s,
when a breakthrough happened.
Researchers found that most dreams occur during a phase of sleep called
rapid eye movement, or REM, sleep-a recurring period of light sleep
which the eyes can be seen to dart around beneath the eyelids.
This prompted an explosion of research into how the brain works during
sleep-leading, in 1977, to a hypothesis that many felt summed it
This was also the proposal that, in Cartwright's view,
killed the field.
Two Harvard researchers in psychiatry, J. Allan Hobson and Robert
proposed that both REM sleep and dreaming consist of
repeated bursts of
electrical activity from our primitive, "reptilian"
brain, the brain stem.
The brain stem controls basic functions such as
digestion and breathing.
In REM sleep, the Harvard researchers said, the brain stem randomly
electrical signals up into the forebrain, the brain's more
division, stirring up a nonsensical jumble of thoughts,
memories and images.
With this barrage of information, the theory went, the forebrain does
it knows how to do: It tries to make sense of it, by arranging it
semblance of a story line. After waking, the person may
again try to figure
out the experience, injecting it with still more
meaning that wasn't there.
This hit the dream research community like a bomb, because to some it
suggested there was no further use for dream research. Funding for the
soon dried up, though some blame this on Reagan-era budget cuts.
Many researchers resented the idea that dreams were meaningless. Some
raised obvious objections: For instance, how does this random
explain a common type of dream in which a thirsty sleeper
dreams of getting
a glass of water?
But it was hard to challenge the Harvard researchers, armed as they
with years of detailed research and powerful credentials.
A staunch challenge finally came in 1997 in a book, "The
Dreams," by Solms, of Royal London Hospital.
Since then, Solms and Hobson have been key figures in opposing sides of
debate. The debate played out further in an issue this spring in the
journal Behavioral and Brain Sciences, in which both researchers wrote
Solms has attacked the Hobson group's theories by declaring that the
advanced forebrain, not the brain stem, generates dreams.
This shows that dream imagery is "actively constructed through complex
cognitive processes," not random activity, Solms says. Thus, he added
interview, "a thought, a fear, a memory or a desire can actually
ball rolling" for a dream.
To demonstrate the forebrain's critical role in dreaming, Solms cited
almost 1,000 published cases of people who had stopped dreaming after
Two specific forebrain areas are essential for dreaming, he said; in
evidence of this, their destruction wipes out a person's ability to
Perhaps the more important of the two, he said, is a circuitry system
controls goal-seeking behavior, near the bottom front of the
This region, called the ventro-medial frontal quadrant, "is accordingly
described as the 'seeking' or 'wanting' command system of the brain,"
according to Solms. "This suggests that these motivational mechanisms
essential for the generation of dreams."
That's why people with injuries in this area not only stop dreaming,
become apathetic, Solms wrote. He had plenty of examples: Brain
commonly used to destroy this region purposely in lobotomies.
The other brain area needed for dreaming, Solms said, is a part of the
forebrain's outer right side that creates the sense of
space. This area is called the
Harvard's Hobson and two colleagues have made some concessions. They
backed off the claim that dream story lines are random,
emotion is involved in shaping dream story lines.
But they still say dreams
are rooted in electrical and chemical
changes in the brain stem. This, to
Solms, still denies the mind and
personality's crucial role in dreaming.
Freud's stirring theories reverberate through the whole debate. To some
extent, the opposing arguments are Freudian and anti-Freudian-a fact
rankles some dream researchers.
"To me it's an amazing comment when there are still Freudians and
[Carl Jung was Freud's student] 100 years later," said G.
a research professor at the University of California
at Santa Cruz. "No
data convinces them."
Solms' central claim-that goal-seeking systems trigger dreaming-recalls
Freud's claim that a wish prompts the dream.
Solms also has speculated that the dreaming brain may blunt or shut off
impulses headed for its judgment and logic section, the prefrontal
Some researchers find this reminiscent of Freud's repression
Hobson and colleagues focus more on physical explanations, trying to
aside harder-to-measure mental or psychological factors.
What looked to Freud like "repression," they say, is simply the result
chemical changes that make us extremely forgetful during dreams.
changes are due to a shift, during REM sleep, in the types of
messenger molecules that the brain stem produces and that
While century-old theories are making the debate more stimulating, or
frustrating, much newer research is helping create some areas of
Researchers use a modern imaging technique, positron emission
PET, to closely map brain activity based on levels of
blood flow or sugar
usage throughout the brain.
Unlike Solms' research, the PET studies don't show which brain regions
absolutely needed for dreaming. They help answer more general
which brain areas are most and least active during REM
Least activated is much of the frontal cortex, a part of the advanced
forebrain considered the truly most evolved section. This area is
for day-to-day waking functions such as judgment, logic,
thought and the short-term memory we use while at work
on a task.
Also usually inactivated is the primary visual cortex, a complex of
that "reads" light information sent from the eyes.
However, a related zone that picks up signals from the primary visual
cortex is activated: the visual association cortex. This structure
convert the received signals into something that makes sense by
and recognizing objects.
Solms found that injuries to this structure, which produce visual
in waking people-such as color-blindness-create the same
deficits in dream
The largest area activated during REM sleep is the loop of circuitry
responsible for emotions, called the limbic and paralimbic regions.
are in the midbrain and surrounding tissue in the middle of the
This complex includes what Solms called the "wanting" circuitry
for dreaming. It also contains another brain structure that
seems to be of
key importance in REM sleep: the amygdala.
The amygdala is a small, almond-shaped structure responsible for
and fear. It communicates closely with almost all the other
active in REM sleep, but has only weak connections to
those that aren't,
Researchers find that intriguing, because most dream research has shown
that negative emotions, especially anxiety, predominate in dreams.
The combined findings suggest that dream emotion shapes the dream story
line, not the other way around as common sense might suggest, Hobson
"Thus in a classic anxiety dream, the plot may shift from feeling lost,
not having proper credentials, adequate equipment or suitable
missing a train. These plots all satisfy the driving
emotion - anxiety -
while being only very loosely associated with one
The amygdala is also known to influence memory storage processes in the
neighboring hippocampus, Hobson and colleagues say. That suggests one
where memory may enter the picture.
The hippocampus is crucial for memory. It was the same region in which
Massachusetts Institute of Technology researchers measured electrical
activity of rat nerve cells, to conclude that the rats were dreaming
their maze treks.
A brain structure strongly activated during REM sleep - even more so
in waking - is the basal ganglia, Hobson notes. This is a group
cells in the center of the brain responsible for generating
This could explain the seemingly endless fictional motion in dreams,
researchers note. The phenomenon may be familiar to anyone who has
that if everyone in their dream starts just sitting around, he
or she soon
None of this addresses exactly how we create the dream story line. The
answer may have to await still better brain imaging technologies.
"We can do more and more complex three-dimensional reconstructions of
what's going on in the brain - until we get to see what a single cell
doing," said Deirdre Barrett of Harvard Medical School, editor of
Another line of research that will fill out the picture, Barrett added,
studies focusing on how dreams relate to the dreamer's real life.
"A lot of what dreaming is about is practicing," she said. "There's
body of research over the past 10 years showing that when a
studying a language, that language shows up in a lot of
blocking REM sleep inhibits the learning."
Not everyone agrees. One skeptic is Robert P. Vertes, a professor of
psychobiology at Florida Atlantic University in Boca Raton.
He cited cases of people who take medications that "virtually
abolish REM sleep." These patients have normal memory and
abilities, Vertes said.
Despite the disagreements, the flood of new research is clarifying
said Domhoff, of Santa Cruz.
"There's a confluence of events that has everyone rethinking this a
Technology Peeks Within The Sleeping Brain
ALTHOUGH SCIENTISTS are showing an intense new interest in studying
experts say, they have barely begun using some of the most
technologies available to do so.
For instance, researchers are just starting to use an imaging technique
that will let them study precisely how memories may be stored during
And maybe-just maybe-an existing technique for reading animal
could serve to make the first crude, silent films of
"These are questions that will have to wait to be answered, not because
we're lacking the technology, but because the research hasn't been
yet," said Matthew Wilson, an associate professor of brain and
sciences at the Massachusetts Institute of Technology.
Dream researchers have been using machines for the past decade that
which parts of the brain are at work during sleep.
The most widely used technology for this, called PET for positron
tomography, creates computer images showing which parts of
the brain are
most active in the phase of sleep associated with
dreaming. It works by
measuring blood flow and the levels at which
different brain regions use up
Yet sleep researchers are just beginning to use a technique that
new picture of brain activity every few seconds, instead of
every minute or
so as with PET.
This technology, called fMRI (functional magnetic resonance imaging),
produces sharper images. It discriminates between brain regions
the size of those PET can distinguish.
"I'm sure that within a couple of years there will be more than 10
published on fMRI in sleep, because fMRI is much more widely
PET," said Pierre Maquet, a research fellow with
Wellcome Department of
Cognitive Neurology, University College,
Maquet said his laboratory has begun fMRI research, which works by
measuring the brain's oxygen usage rather than blood flow. These
can answer very detailed questions, he explained.
For instance, Maquet said, one theory holds that during waking, the
neocortex stores memories temporarily in the hippocampus, a small
the side of the brain, and that the reverse happens during
sleep. FMRI can
"We can describe how the hippocampus is talking to the neocortex," he
Another line of research is a technique in which researchers
stimulate specific brain regions by bringing magnetic
coils near the head.
This allows research subjects to report the effects of brain activation
specific areas, without having to undergo surgery, as they did in
studies of this type (researchers studied patients who were
operations for some other reason).
The new technique, called transcranial magnetic stimulation, has yet to
widely used in dreaming research. But it will in the years ahead,
researchers said. This has "enormous research potential," said Mark
a psychoanalyst with Royal London Hospital and author of
several papers and
books on dreaming.
The Holy Grail for some dream researchers is to somehow tap into brains
produce some sort of films of actual dreams.
"My vision of the future is that you could holographically project
said Alan Siegel, author of two books on dream research and
president of the Association for the Study of Dreaming.
Actually, the technology to do something like that-at least in
exist, experts say.
MIT researchers in 1999 showed films of ordinary real-life scenes to
while recording electrical activity in their brain cells. By
measurements through a computer, they reconstructed films
the originals, though much blurrier. The findings
were published in the
Sept. 15, 1999, issue of the Journal of
"These are things that are accessible to experimental scrutiny. You can
in, you can map out how a particular scene or image is
MIT's Wilson. Whether dreams can be taped this way,
he said, "will
ultimately have to be addressed."