Mathematical Digest

Short Summaries of Articles about Mathematics
in the Popular Press

"Secrets of an Acid Head," by Dana Mackenzie. New Scientist, 23 June 2001,pages 26-30.

In the 1920s, a University of Chicago neuroscientist categorized hallucinationsinto four types: tunnels, spirals, cobwebs, and honeycombs. Today,mathematician and neuroscientist Jack Cowan, also at Chicago, is trying tomathematically model brain activity that could produce hallucinations. Cowanand co-workers focused on modeling neural activity in the visual cortex to seewhat kind of activity could bring about hallucinations. One kind of model wasused for tunnels and spirals, and another for cobwebs and honeycombs. "LSDusers see spirals and tunnels because those are the real-world objects that fitthe patterns of neural firing in their cortex," Mackenzie writes.

--- Allyn Jackson