THIS IS THE BRAIN ON HALLUCINOGENS

Albert Hoffman, the Swiss chemist who discovered LSD in 1943 and was the
first person known to have taken an acid trip, described his experience as
having two parts: "On the way home, my condition began to assume threatening
forms," he wrote in his journal. "My surroundings had now transformed
themselves in more terrifying ways. Everything in the room spun around, and
the familiar objects and pieces of furniture assumed grotesque, threatening
forms."

But after a while, "the horror softened and gave way to a feeling of good
fortune and gratitude."

"Kaleidoscopic, fantastic images surged in on me, alternating, variegated,
opening and then closing themselves in circles and spirals, exploding in
colored fountains, rearranging and hyridizing themselves in constant flux,"
he wrote. "Every sound generated a vividly changing image, with its own
consistent form and color."

Users of LSD and many psychiatrists who have used the drug in therapy
sessions say that these kinds of effects provide a window into the human
unconscious. When people let go of the past in an altered state, they can
dredge material from the deep within themselves.

Or can they? To Dr. Jack Cowan, a mathematician at the University of Chicago
and a number of other scientists who study the architecture of the brain's
visual areas, the dancing geometical patterns observed by Dr. Hoffman are
not in the least mysterious. Cells in primary visual areas are specialized
for detecting edges and contours in normal vision, he said.

When these cells are stimulated by a hallucinogen, they automatically
produce visions of spirals, pinwheels, tunnels, funnels, spirals,
honeycombs, checkerboards and cobwebs. As the brain struggles to make sense
of these images, it may make up a story to explain what it is happening, he
said.

People may find the results helpful or insightful, he said, but they flow
not from some mysterious netherworld world but from the architecture of
their own brains.