Text: BRAIN SHRINKS, YET THINKS By Paul Pietsch This article originally appeared in Science Digest, October 1983 (vol. 91 No. 10) Anatomy textbooks contain detailed maps of "normal" human brain function. Sight, we are told, resides in one region, hearing in another. But one fascinating patient who was referred to the eminent British neurologist John Lorber demonstrates that there are exceptions to every rule. Lorber, who specializes in birth defects caused by fluid buildup within the interior of the brain, tells of a 26 year- old man referred to him for a brain scan. Ordinarily, the walls of the cerebrum are 4-5 millimeters thick. This man's cerebrum had been squashed by fluid pressure--a condition known as hydrocephalus--to a thickness of less than one millimeter. * That Lorber's patient was alive at all seems incredible. But he was socially normal, had an IQ of 126 and had earned a first class honors degree in mathematics. His relative lack of gray matter had not apparently affected his intelligence. How could this possibly be? If the way the brain functions is similar to the way a hologram functions, that one-millimeter sliver might suffice. Certain holograms can be smashed to bits, and each remaining piece can reproduce the whole message. A tiny fragment of this page, in contrast, tells little about the whole story. Observations such as Lorber's suggest that input- output functions of different parts of the brain can be shifted and that there's a great deal of functional plasticity in it. Indeed, in recent years, plasticity has become a major topic among neuroscientists. That valid maps exist at all--and they do--suggests that there is a strong tendency as we mature for certain regions to assume particular chores. But that a brain one millimeter thick functions as well as its 4 to 5 millimeter counterpart illustrates that these tendencies are not etched in stone. *see Roger Lewin, "Is Your Brain Really Necessary?" Science 210 December 1980, p. 1232

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