Hallucinations Lead To Insight Into The Visual Brain
- Dear Friends and All,
I checked this story out with an expert (thanks Lee) and am delighted, that
it's the real deal.
This is pretty interesting and important news, for folks with visual
impairments, although most of the folks I know who are blind, see far
better, than the folks who are not.
I had a few expierences with hallucinations in the 60's, and they certainly
were an expierence, in how I percieved the world around me and within me.
Steve & Yofi
Steven Palmer Disabled Advocate
British Columbia, Canada
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Hallucinations Lead To Insight Into The Visual Brain
Scientists are deducing the internal circuitry of the visual brain by
mathematically reproducing the geometric hallucinations people see when
ingest mind-altering drugs, view bright, flickering lights or encounter
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
the complexities of vision, the workings of the brain and even the origins
"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,
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
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
the brain can generate patterns of activity that underlie hallucinations,"
These geometric hallucinations take the form of checkerboards, honeycombs,
tunnels, spirals and cobwebs, a phenomenon originally studied as early as
1920s and 1930s by the late Heinrich Klüver, a pioneering University of
"Because we know how the eyes are wired to the visual cortex, we can
what the patterns actually look like there," said Cowan. "They correspond
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,
recent advances in brain anatomy and physiology, of the strong short-range
connections and weaker long-range connections between neurons in the visual
"It is a situation where you have something strong and something else
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,
spectrum changes in ways that can be calculated," Cowan explained. "It's
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
world's only university faculty member who holds dual appointments in
mathematics and neurology. In 1986, he organized one of the founding
of the Santa Fe Institute, a private, non-profit research and education
devoted to the study of complexity and complex adaptive systems. He became
interested in geometric hallucinations in the late 1970s, when he realized
they may provide clues regarding the brain's circuitry.
"Producing hallucinatory images in the brain could be understood in terms
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,
amplified into a pattern that reflects the architecture of the brain. The
just takes the noise and shapes it into a pattern," Cowan said. "In the
geometric visual hallucinations this is a direct consequence of the pattern
connections in the visual cortex."
Some researchers foresee the day that blind people will see again following
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
movement and depth and texture and surfaces. The circuitry involved in all
that is complicated and needs to be worked out."
Cowan, Bressloff and their colleagues are ready to continue the work.
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
the intrinsic circuitry of the cortex."
As for the origins of art, last June Cowan participated in a conference on
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
take hallucinogens," Cowan said. - By Steve Koppes
[Contact: Steve Koppes]