SEEING MORE THAN MEETS EYE

Science Finding Hallucinations May Be Reflection Of Brain Pathways

Near-death experiences, in which people believe they see the bright
light of heaven at the end of a tunnel, may be nothing more than the
brain cells that process vision lighting up in such a way so as to
reveal the circular pattern of how they are wired together.

New research also indicates that prehistoric cave and rock art
depicting spirals, zigzags and other geometric forms may have been
done by artists experiencing the same kind of drug-induced
hallucinations that people today have when they take LSD, mescaline,
Ecstasy and other psychedelic compounds.

A visual hallucination is defined as seeing something that's not
there. They are relatively common, and almost all cultures from
prehistoric times on have used drugs to induce hallucinations for
religious, healing and artistic purposes.

But science now suggests that near-death images and other
hallucinations involving geometric patterns are really there-- on the
inside of the brain.

Inducing Creative Mood

People like Arthur Conan Doyle, Aldous Huxley, Cary Grant, Allen
Ginsberg, Tallulah Bankhead, the Beatles, Charles Dickens, Timothy
Leary and Salvador Dali, who used hallucinogens in the hopes of
inducing a creative mood, were actually lighting up their brain wiring.

"[It] surged upon me an uninterrupted stream of fantastic
[kaleidoscopic-like] images of extraordinary plasticity and
vividness," is how Albert Hoffman, the brilliant Swiss chemist,
described his first experience with LSD, a compound he had synthesized
in 1938.

Hallucinations can also be caused by anesthetics, fatigue, hunger,
stress, alcohol, fever, adverse drug reactions, sleep deprivation,
bright flickering lights and even pressure on the eyeballs.

Normally, the 100 million neurons of the credit-card size visual
cortex at the back of the head convert what our eyes see into edges
color, depth and other features, and then reassemble the pieces into
recognizable scenes of the outside world.

The process works fast. About 40 milliseconds after seeing an object,
edge detectors are activated and in another 40 milliseconds the edges
become pieced together into contours and the beginnings of surfaces.
This information goes to other parts of the brain to be compared with
stored memories.

In far less than a second you've basically solved the problem of
vision, of remembering, recognizing and sorting out what the object
is.

In the case of a hallucination, this does not happen. Through the
action of drugs or other influences, the edge detectors become
disengaged from the rest of the network and begin firing on their own.

The resulting hallucination reflects the pinwheel pattern of brain
cells that process lines, curves and other geometric shapes, providing
a remarkable view of the physical architecture of the visual cortex,
according to recently published findings by Jack Cowan of the
University of Chicago and Paul Bressloff of the University of Utah.

"It's almost like seeing your own brain through a mirror," Cowan said.
"You're basically seeing patterns that your own brain is making."

4 Basic Groups

Cowan, who is a mathematician and a neurologist, has been studying
hallucinations for 20 years. He was intrigued by the work of another
U. of C. scientist, Heinrich Kluver, who in the 1920s and 1930s
classified the drawings of people experiencing drug-induced
hallucinations into four basic categories--tunnels and funnels;
spirals; lattices; and cobwebs.

Based on new findings from optical imaging, in which scientists can
actually see which neurons light up in the visual cortex of cats and
monkeys when they view different lines and contours, Cowan, Bressloff
and their colleagues developed a mathematical model that can
accurately predict the shapes of different hallucinations.

"We calculated that given the kinds of anatomy in the visual cortex,
there are only four kinds of patterns it will make when it goes
unstable," Cowan said. "It turns out that those four kinds of patterns
we get from the math correspond exactly to the four classes of
patterns that Kluver ended up with based on his looking at the drawings."

Terry Sejnowski, director of the Salk Institute's Computational
Neurobiology Laboratory, said the work of Cowan and Bressloff could
have wide application in the areas of artificial intelligence and
artificial vision.

"They have created a mathematical model which replicates surprisingly
well the states that the brain gets into when it's having visual
hallucinations," he said. "These hallucinatory states are really
abnormal conditions. Sometimes you learn a lot about a complex system
from the conditions which occur when it breaks down or when it's not
operating under normal conditions."

The mathematical study of vision is also helping to explain near-death
experiences. Essentially they are physical representations of
striplike columns of neurons in the visual cortex that form a tunnel
pattern.

"What actually happens when somebody takes a drug is the first thing
they experience is a very bright light in the center of the visual
field, which is very reminiscent of this sort of light in the tunnel
when people think they see heaven beckoning in the distance,"
Bressloff said.

"What seems to happen is that this bright light spreads across the
visual field and from that state then this structure emerges which is
the seed for the hallucination pattern," he said.

Drug-Induced Drawings

Since spirals, tunnels, zigzags and other hallucinatory patterns can
be found in the art of almost all cultures and go back more than
30,000 years, many anthropologists speculate that they were done under
the influence of hallucinogenic drugs or self-induced trances, and
that these experiences served as the origin of abstract art.

The foremost masters of hallucinogenic experiences are shamans, ritual
practitioners in hunting-and-gathering societies who enter altered
states of consciousness to achieve a variety of ends that include
healing the sick, foretelling the future, meeting spirit-animals,
changing the weather and controlling animals by supernatural means,
according to Jean Clottes, scientific adviser to the French ministry
on prehistoric art, and David Lewis-Williams, professor of cognitive
archeology at the University of Witwatersrand in Johannesburg, South
Africa.

In their study of shamans, religious mystics and visionaries around
the world, Clottes and Lewis-Williams found that while drugs are
widely used to induce hallucinations, trances are also used to produce
unusual mental imagery. Trances can be induced through sensory
deprivation, prolonged social isolation, intense pain, vigorous
dancing and insistent, rhythmic sound, such as drumming and chanting.

3 Stages Of Trances

In their book, "The Shamans of Prehistory: Trance and Magic in the
Painted Caves," Clottes and Lewis-Williams outline three stages of
trance.

In the first stage trance, people "see" geometric forms, such as dots,
zigzags, grids, parallel lines, nested curves and meandering lines. In
the second stage, subjects try to make better sense out of the
geometric imagery by illusioning them into objects of religious or
emotional significance, such as construing a zigzag line into a snake.
The third stage is reached via a vortex or tunnel, at the end of which
is a bright light. When people emerge from the tunnel they find
themselves in a bizarre world where geometric patterns become mixed
with monsters, people and settings. It is in this stage where the
drawings of humans with animal features occur.

Clottes and Lewis-Williams concluded: "We emphasize that these three
stages are universal and wired into the human nervous system, though
the meanings given to the geometrics of Stage 1, the objects into
which they are illusioned in Stage 2, and the hallucinations of Stage
3 are all culture-specific, at least in some measure, people
hallucinate what they expect to hallucinate."