Clarkson Integrator

Issue date: 9/15/08 Section: Features

Media Credit: Doris Tsao (MCT) Functional MRI images light up pea-sized regions in the human brain that specialize in recognizing faces more than other objects. Usually the "fusiform face area'' on the right side is active, but sometimes its left-side twin is called upon.

Ever wonder why it's so much easier to remember people's faces than their names?

Neuroscientists have an explanation. They've identified a pea-sized region in the brain that reacts more strongly to faces than it does to cars, dogs, houses or body parts.

"The evidence is overwhelming that there is a specialized system dedicated to processing faces and not other objects," said Doris Tsao, a neuroscientist at Massachusetts General Hospital in Boston.

It's called the "fusiform face area," because it vaguely resembles a spindle "fusus" in Latin. It's about halfway back in the head, near the bottom of the visual cortex, the part of the brain than handles vision.

Actually, most people have two FFAs, one on each side of the head, but the one on the right is dominant, the other a backup.

The FFA system explains "why we are so good at recognizing and remembering faces," Tsao said. "A brief glance at a face conveys a wealth of information about identity, expression, gender, age, mood, intent, attractiveness, social states and even honesty."

Researchers say evolution may explain why humans and other primates developed a chunk of brain tissue dedicated to face recognition it helped them quickly spot friends and foes. Our ancestors who were better able to distinguish faces tended to survive and reproduce better than others.

"The ability to extract this information within a fraction of a second of viewing a face is important for normal social interaction, and has probably played a critical role in the survival of our primate ancestors," said Nancy Kanwisher, an investigator at the McGovern Institute for Brain Research in Cambridge, Mass.

Understanding how face recognition works can have practical applications, Tsao said. Insights into these brain circuits may help prevent or treat depression, autism or social disorders. FFA images also may help scientists understand prosopagnosia, an impairment in the recognition of faces that's also known as face blindness.

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