Keys to expertise in the brain.

A small brain area often treated as solely responsible for face recognition actually fosters expertise at identifying items in any category a person strives to master, from birds to cars to made-up stuff, a new study finds.

Earlier investigations found that viewing faces activates a section of the visual cortex located near the back of the brain's outer layer. The most pronounced neural responses appear on the right side of the structure, called the fusiform face area, or FFA.

Activity there similarly surges as volunteers peruse whatever objects or creatures they know a lot about, say psychologist Isabel Gauthier of Vanderbilt University in Nashville and her colleagues. This brain response occurred in 11 car buffs as they examined successive pictures of vehicles of different makes and models and in 8 bird aficionados as they inspected images of different avian species, the scientists assert.

Neither car experts viewing bird species nor bird experts viewing various cars showed such FFA action.

In both groups, however, FFA activity also rose markedly as volunteers looked at pictures of familiar objects, such as a chair and a television set, Gauthier's group reports in the February NATURE NEUROSCIENCE. The researchers used functional magnetic resonance imaging devices to measure the extent of magnetic signal changes--an indirect sign of rising or falling cell activity--in three brain areas thought to support face recognition.

In a related study led by Gauthier, published in the June 1999 NATURE NEUROSCIENCE, volunteers practiced placing members of an imaginary group--dubbed greebles by the researchers and consisting of plantlike objects with slightly varying shapes--into families. People who excelled at this task displayed elevated FFA activity during ensuing attempts at identifying pairs of matching greebles.

The organization of neurons in and around the FFA supports the recognition of defining configurations of any category's members if a person has had enough experience with that category, the researchers theorize. In their view, this unconscious process precludes the need to consider numerous features for, say, each face or object.

Scrutiny of different faces begins shortly after birth and thus may strongly influence FFA function by adulthood, the researchers hold. This influence need not reflect an innate capacity for face recognition in the FFA, as suggested by some scientists.