Unmasking the Brain

The human brain is usually thought of as a single organ, and when it is running smoothly, that is the overall effect. But the brain is actually a bundle of many structures, weirdly shaped,*and put together in such a complex tangle that a simple cutaway model gives a poor impression of the whole. And only in the age of tranquilizers has medical science begun to learn how different drugs affect individual parts of the brain. In Philadelphia last week, physicians at the annual meeting of the American Academy of General Practice were fascinated by a 3-ft. model showing the brain's components in 20 layers of translucent plastic, and wired for colored lights to elucidate some of its workings.

Built for New Jersey's Wallace Laboratories, makers of meprobamate (best known as Miltown), the model illustrated both basic brain physiology and the effects of various tranquilizing drugs, as reported by Dr. Harold E. Himwich of Galesburg State Research Hospital in Illinois. To spell out his findings, a 16-minute recording was played, while a tape of recorded instructions controlled the illustrative lights in the model. To the visiting G.P.s, most of whom had given no thought to the brain's anatomy since their first year in medical school, the technical jargon was almost as forbidding as to a layman. Crux of the matter: drugs influence mental function mainly through their effects on two parts of the brain: 1) the primitive midbrain's reticular (little network) formation, and 2) the connections between the thalamus (inner chamber) and the outer cortex (bark), the most sophisticated and evolutional-ly the newest part of the brain. Dr. Himwich reported:

P:Tranquilizers of the phenothiazine class (notably chlorpromazine and prochlorperazine) reduce the activity of the reticular alertness center and intensify the sleepiness pattern of the thalamocortical fibers.

Rauwolfia drugs from Indian snakeroot (best known: reserpine) stimulate the reticular alertness center and have little effect on the sleep pattern, are therefore less sedative in action. P: Meprobamate, in moderate doses, usually has no effect on the alertness center and little on the sleep pattern; its tranquilizing action must work through other parts of the brain.

P:Barbiturates depress the alertness center and intensify the sleep component, are therefore doubly sedative.

One unsedated physician was alert enough to step behind the curtain to examine the model brain's wiring. Said he: "Anybody who can keep this thing running must also be able to give firsthand testimony on the various tranquilizers. It would make a nervous wreck out of me without my Miltown."

*And more weirdly named for the objects their shapes suggested to ancient anatomists, e.g., amygdala (almond), torcular Herophili (wine press of Herophilus), hippocampus (sea horse), mammillary body (little breast, or nipple).

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