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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 that
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 mazes,
were also striking for their use of the newest brain monitoring technology.
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 scientists
about what functions dreams may serve. Rather, the research drew attention
to a field of research that, its participants say, is undergoing a
revitalization and a small revolution.

"There really has been an enormous renaissance in dream science," said Mark
Solms, a psychoanalyst with Royal London Hospital and author of several
books and papers on dreaming. "Suddenly everyone wants to do research in
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 theories of
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 Cartwright,
chairwoman of the psychology department of Rush-Presbyterian-St. Luke's
Medical Center in Chicago. "We've been better able to tie together the
anatomy and the creative functions of dreams."

These studies show that during the phase of sleep most closely associated
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 almost
always duped into believing we're awake? How do we come up with these weird
dreams in the first place?

Debate over these questions boiled over into what some researchers call a
small revolt in the past four years-another reason they say the field is

A theory that has held sway since the late 1970s suggests dreams are simply
random, meaningless brain activity. That idea convinced many that dream
research has little use, and triggered a sharp drop in government and
private funding for the work, Cartwright said.

"It really killed the field," she said.

This is changing, she added: Researchers have successfully challenged this
in the past four years, giving a lift to scientists who propose all sorts
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 dreams
are an evolutionary adaptation for rehearsing threatening situations; that
they were originally a form of waking thought in lower animals; and, a bit
more blandly, that they just help us wake up.

But a handful of supposed functions for dreams seems particularly popular
among researchers, including the claim that dreams aid in memory, learning
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 emotional
memories. That is, they help us deal with emotional problems by absorbing
them into our network of memories, comparing them with similar past
problems and, perhaps, looking for solutions.

According to Yale University's Dr. Morton F. Reiser, the latest research
supports this view. This is why "the dream in psychiatry is shifting toward
a more interesting and prominent position," Reiser wrote in an article in
the March issue of the American Journal of Psychiatry.

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 intense
debate remains.

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 represents
an unfulfilled wish, rooted in unresolved childhood traumas that the
dreamer has pushed out of his or her waking consciousness.

A therapist's job, Freud said, is to extract the truth about these traumas,
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 during
which the eyes can be seen to dart around beneath the eyelids.

This prompted an explosion of research into how the brain works during REM
sleep-leading, in 1977, to a hypothesis that many felt summed it up nicely.
This was also the proposal that, in Cartwright's view, killed the field.

Two Harvard researchers in psychiatry, J. Allan Hobson and Robert McCarley,
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 shoots
electrical signals up into the forebrain, the brain's more advanced
division, stirring up a nonsensical jumble of thoughts, memories and images.

With this barrage of information, the theory went, the forebrain does all
it knows how to do: It tries to make sense of it, by arranging it into some
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 work
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 activation
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 were
with years of detailed research and powerful credentials.

A staunch challenge finally came in 1997 in a book, "The Neuropsychology of
Dreams," by Solms, of Royal London Hospital.

Since then, Solms and Hobson have been key figures in opposing sides of a
debate. The debate played out further in an issue this spring in the
journal Behavioral and Brain Sciences, in which both researchers wrote
competing papers.

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 in an
interview, "a thought, a fear, a memory or a desire can actually get the
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
forebrain injuries.

Two specific forebrain areas are essential for dreaming, he said; in
evidence of this, their destruction wipes out a person's ability to dream.

Perhaps the more important of the two, he said, is a circuitry system that
controls goal-seeking behavior, near the bottom front of the forebrain.

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 are
essential for the generation of dreams."

That's why people with injuries in this area not only stop dreaming, but
become apathetic, Solms wrote. He had plenty of examples: Brain surgeons
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 three-dimensional
space. This area is called the parieto-temporal-occipital junction.

Harvard's Hobson and two colleagues have made some concessions. They have
backed off the claim that dream story lines are random, acknowledging that
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 that
rankles some dream researchers.

"To me it's an amazing comment when there are still Freudians and Jungians
[Carl Jung was Freud's student] 100 years later," said G. William Domhoff,
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 cortex.
Some researchers find this reminiscent of Freud's repression theory.

Hobson and colleagues focus more on physical explanations, trying to leave
aside harder-to-measure mental or psychological factors.

What looked to Freud like "repression," they say, is simply the result of
chemical changes that make us extremely forgetful during dreams. These
changes are due to a shift, during REM sleep, in the types of chemical
messenger molecules that the brain stem produces and that constantly flood
the brain.

While century-old theories are making the debate more stimulating, or
frustrating, much newer research is helping create some areas of agreement.

Researchers use a modern imaging technique, positron emission tomography or
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 are
absolutely needed for dreaming. They help answer more general questions:
which brain areas are most and least active during REM sleep.

Least activated is much of the frontal cortex, a part of the advanced
forebrain considered the truly most evolved section. This area is crucial
for day-to-day waking functions such as judgment, logic, goal-directed
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 cells
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 helps
convert the received signals into something that makes sense by matching
and recognizing objects.

Solms found that injuries to this structure, which produce visual deficits
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. These
are in the midbrain and surrounding tissue in the middle of the forebrain.

This complex includes what Solms called the "wanting" circuitry necessary
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 anxiety
and fear. It communicates closely with almost all the other brain regions
active in REM sleep, but has only weak connections to those that aren't,
Hobson observed.

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 and
colleagues say.

"Thus in a classic anxiety dream, the plot may shift from feeling lost, to
not having proper credentials, adequate equipment or suitable clothing, to
missing a train. These plots all satisfy the driving emotion - anxiety -
while being only very loosely associated with one another."

The amygdala is also known to influence memory storage processes in the
neighboring hippocampus, Hobson and colleagues say. That suggests one way
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 of
their maze treks.

A brain structure strongly activated during REM sleep - even more so than
in waking - is the basal ganglia, Hobson notes. This is a group of nerve
cells in the center of the brain responsible for generating voluntary
physical movements.

This could explain the seemingly endless fictional motion in dreams, the
researchers note. The phenomenon may be familiar to anyone who has noticed
that if everyone in their dream starts just sitting around, he or she soon
wakes up.

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 is
doing," said Deirdre Barrett of Harvard Medical School, editor of the
journal Dreaming.

Another line of research that will fill out the picture, Barrett added, is
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 been a
body of research over the past 10 years showing that when a person is
studying a language, that language shows up in a lot of dreams. And
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 completely
abolish REM sleep." These patients have normal memory and learning
abilities, Vertes said.

Despite the disagreements, the flood of new research is clarifying issues,
said Domhoff, of Santa Cruz.

"There's a confluence of events that has everyone rethinking this a little

Technology Peeks Within The Sleeping Brain

ALTHOUGH SCIENTISTS are showing an intense new interest in studying dreams,
experts say, they have barely begun using some of the most powerful
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 sleep.
And maybe-just maybe-an existing technique for reading animal brain cells
could serve to make the first crude, silent films of actual dreams,
researchers say.

"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 done
yet," said Matthew Wilson, an associate professor of brain and cognitive
sciences at the Massachusetts Institute of Technology.

Dream researchers have been using machines for the past decade that show
which parts of the brain are at work during sleep.

The most widely used technology for this, called PET for positron emission
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 creates a
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), also
produces sharper images. It discriminates between brain regions one-fifth
the size of those PET can distinguish.

"I'm sure that within a couple of years there will be more than 10 papers
published on fMRI in sleep, because fMRI is much more widely available than
PET," said Pierre Maquet, a research fellow with Wellcome Department of
Cognitive Neurology, University College, London.

Maquet said his laboratory has begun fMRI research, which works by
measuring the brain's oxygen usage rather than blood flow. These studies
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 region in
the side of the brain, and that the reverse happens during sleep. FMRI can
investigate this.

"We can describe how the hippocampus is talking to the neocortex," he said.

Another line of research is a technique in which researchers electrically
stimulate specific brain regions by bringing magnetic coils near the head.

This allows research subjects to report the effects of brain activation in
specific areas, without having to undergo surgery, as they did in past
studies of this type (researchers studied patients who were undergoing
operations for some other reason).

The new technique, called transcranial magnetic stimulation, has yet to be
widely used in dreaming research. But it will in the years ahead,
researchers said. This has "enormous research potential," said Mark Solms,
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 to
produce some sort of films of actual dreams.

"My vision of the future is that you could holographically project dreams,"
said Alan Siegel, author of two books on dream research and former
president of the Association for the Study of Dreaming.

Actually, the technology to do something like that-at least in animals-may
exist, experts say.

MIT researchers in 1999 showed films of ordinary real-life scenes to cats,
while recording electrical activity in their brain cells. By running the
measurements through a computer, they reconstructed films recognizably like
the originals, though much blurrier. The findings were published in the
Sept. 15, 1999, issue of the Journal of Neuroscience.

"These are things that are accessible to experimental scrutiny. You can go
in, you can map out how a particular scene or image is represented," said
MIT's Wilson. Whether dreams can be taped this way, he said, "will
ultimately have to be addressed."

-Jack Lucentini


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