Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: THURSDAY, October 7, 1993                   TAG: 9310060007
SECTION: EXTRA                    PAGE: 1   EDITION: METRO  
SOURCE: Joel Achenbach
DATELINE:                                 LENGTH: Medium

THE BRAIN HAS ITS OWN SPECIAL PICTURE FILE

A: Someone might hand you an old photograph and you'll instantly realize it's a picture of, say, Richard Nixon as a boy. You just see it. The incipient ski-slope nose. The juvenile jowls. The tape recorder slung over the shoulder. How does your brain pick up these subtle details so easily?

We know that vision works in multiple stages. Light enters your eyes. Your brain first detects the spots of light and dark. Then, at another neuronal level, it discerns color. Then it registers the horizontal and vertical lines of objects. Then it checks out the corners of objects. All this happens quickly but not instantaneously. What's amazing is that there's an even higher level of detection: A tiny but distinct portion of the brain, in the inferotemporal, appears to be devoted to facial recognition.

That's basically all it does. It tells you that you're looking at Fred and not Barney.

"It's an awesome capability that the brain has," says Robert Desimone, a neuroscientist at the National Institute of Mental Health.

Desimone says this multistep process is poorly understood: It's not quite as simple as step A leads to step B leads to step C. No one doubts that it's fundamentally a mechanical, deterministic process (i.e., it's not a miracle), but for the moment it remains rather inscrutable. Computer scientists would love to know how the brain does the trick, because then maybe they could copy the scheme.

Which leaves us with nothing but the Darwinian answer:

"Faces are incredibly important for primate social life," says Charles Gross, professor of psychology at Princeton, "so the brain has developed an exquisite set of mechanisms so that we can recognize faces well."

Now if the brain would only hurry up and develop a way of remembering the name of the acquaintance who is rapidly approaching with hand extended in greeting.

The Mailbag:

Bernhard S. of Alexandria, Va., asks, "Why are condemned prisoners executed with 2,000 volts over several minutes, instead of 20,000 volts over several seconds?"

Dear Bernie: One reason is, we no longer believe in burning as a way of execution. The stake, the rack, the Iron Maiden and the gibbet are all out of fashion, and likewise we do not choose to execute people with so much voltage that the contact points will catch on fire.

Ron Wright, the Broward County, Fla., Medical Examiner, calculated that the average human being, with a resistance of 500 ohms, would pull 40 amps at 20,000 volts, which translates to 800,000 watts. You don't have to know what the numbers mean to realize that it's a tad excessive.

"You'd actually cook the person," says Wright.

The state of Florida uses about 4,800 volts for a minute. The current is cut off and then resumed a minute later. This happens three times. The first jolt renders the prisoner instantly unconscious and the temperature in the brain is raised to the point where the brain is destroyed.

The problem is, the heart often still beats after the high voltage is removed. The Commonwealth of Virginia deals with this by using a two-phase process, high voltage first and then low voltage, which puts the heart into irreversible quivering, called ventricular fibrillation.

A lovely business, eh?

We think Wright put it well: "The whole thing is, in an odd sort of way, both high-tech and barbaric."

- Washington Post Writers Group