Number 23 (Story #3), February 28, 1991 by Phillip F. Schewe and Ben Stein NEUROMAGNETISM has become increasingly important in the cognitive sciences. Starting with work in 1975 at New York University (Samuel Williamson, 212-998-7692), the number of labs worldwide that use the brain's magnetism to map sensory functions has grown to 50 or more. Researchers address such questions as: where in the brain is the "mind's eye" or the "mind's ear"? What part of the brain responds when we see a face? The instruments used to measure neural magnetism, magnetometers fashioned from superconducting quantum devices (SQUIDS), are now commercially available from such companies as Siemens (Germany) and BTI (San Diego). The SQUID arrays, usingup to 37 sensors, still employ the older 4-K superconductors since the 77-K superconductor technology is not yet ready. (Scientific American, March 1991.)