Land Mines in the World of Mental Maps

The rising prominence of brain-scanning studies hides some problems

By RICHARD MONASTERSKY

Before entering the machine, you shed pieces of your identity one at a time. First the wedding ring goes, along with the keys and the wallet, with all of its magnetized credit cards. Then glasses, belt, and watch come off. You lie down on a cushioned tray and shut your eyes, as technicians secure...