HALLUCINATIONS PLUS MATHEMATICS PLUS ANATOMY
EQUALS INSIGHT INTO BRAIN ARCHITECTURE

CHICAGO, Jan. 3 -- Scientists are deducing the internal circuitry of the visual brain by mathematically reproducing the geometric hallucinations people see when they ingest mind-altering drugs, view bright, flickering lights or encounter near-death experiences.

The findings by the University of Chicago's Jack Cowan, the
University of Utah's Paul Bressloff and three of their colleagues provide
new insights into the complexities of vision, the workings of the brain and
even the origins of art.

"We take it for granted, but seeing is an amazing process," said
Cowan, a professor in mathematics and neurology. "In something less than a second, we can see objects and classify them under all kinds of differing illumination from very dim to very bright. We're just scratching the surface of what's going on."

The mathematical study of vision and the brain has been accepted for
publication in the journal Neural Computation. Co-authoring the study were Martin Golubitsky, University of Houston; and two of Cowan's former
graduate students, Peter Thomas, Salk Institute for Biological Studies; and
Matthew Wiener, National Institutes of Health.

"We're trying to understand how the intrinsic circuitry of the
visual cortex of the brain can generate patterns of activity that underlie
hallucinations," Bressloff said. These geometric hallucinations take the
form of checkerboards, honeycombs, tunnels, spirals and cobwebs, a
phenomenon originally studied as early as the 1920s and 1930s by the late Heinrich Kluver, a pioneering University of Chicago neurologist.

"Because we know how the eyes are wired to the visual cortex, we can calculate what the patterns actually look like there," said Cowan. "They correspond very closely to the patterns that people report seeing."

A technique called "perturbation theory" proved crucial to
reproducing the geometric patterns, Bressloff said. Also crucial was an
understanding, based on recent advances in brain anatomy and physiology, of the strong short-range connections and weaker long-range connections between neurons in the visual cortex.

"It is a situation where you have something strong and something
else that's weak, so it perturbs the system," Bressloff said.

The mathematics that models the perturbation is, coincidentally,
similar to that used in calculating the Zeeman Effect in quantum mechanics, which describes the physics of the subatomic world. "If you take hydrogen atoms and you put them in a weak magnetic field, their spectrum changes in ways that can be calculated," Cowan explained. "It's called the Zeeman effect." Bressloff noted, however, that "there's no quantum mechanics involved in the actual working of the brain."

Academically trained in physics and electrical engineering, Cowan
may be the world's only university faculty member who holds dual
appointments in mathematics and neurology. In 1986, he organized one of the founding workshops of the Santa Fe Institute, a private, non-profit
research and education center devoted to the study of complexity and
complex adaptive systems. He became interested in geometric hallucinations in the late 1970s, when he realized that they may provide clues regarding the brain's circuitry.

"Producing hallucinatory images in the brain could be understood in
terms of spontaneous pattern formation in the brain," Cowan said. "The
brain makes patterns of activity when it goes unstable." Such instabilities
follow the ingestion of substances such as LSD, psilocybin and cannabis,
which act on control networks in the brainstem that secrete noradrenalin,
seratonin and dopamine, which in turn control brain states.

"If there's any noise-random fluctuations of brain activity-in the
brain, it is amplified into a pattern that reflects the architecture of the
brain. The brain just takes the noise and shapes it into a pattern," Cowan
said. "In the case of geometric visual hallucinations this is a direct
consequence of the pattern of connections in the visual cortex."

Some researchers foresee the day that blind people will see again
following the implantation of a vision computer chip in the brain. "We're a
long way from that," Cowan said. "So far we've only described the
interactions between edge detectors in the visual brain, but there are all
kinds of things going on in the visual cortex. There's detection of color
and movement and depth and texture and surfaces. The circuitry involved in all of that is complicated and needs to be worked out."

Cowan, Bressloff and their colleagues are ready to continue the
work. Bressloff said, "It's just the beginning of a long program of
studying more and more complex hallucination patterns, trying to see how
far we can go with deducing the intrinsic circuitry of the cortex."

As for the origins of art, last June Cowan participated in a
conference on the topic in Montana. Geometric designs are a common design element in cave paintings and prehistoric rock art the world over. Some experts trace the prehistoric origins of art to hallucinogenic experiences.

"A lot of the imagery is clearly related to what people report seeing when they take hallucinogens," Cowan said.

NOTE TO EDITORS: The u in Kluver takes an umlaut. The diacritical mark cannot be transmitted.

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From the Chicago Tribune

Seeing more than meets eye
Science finding hallucinations may be reflection of brain pathways
By Ronald Kotulak
Tribune science reporter

January 1, 2002

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."

Copyright © 2002, Chicago Tribune