From Globe and Mail, January 10, 2008

At first, Kari’s brain surgery seemed like a success. The epileptic seizures that had plagued the 23-year-old New Brunswick native for years were finally gone for good.

But something vital was also missing.

And it wasn’t until Kari returned to university after a summer of recovery, and stranger after stranger approached to inquire about her surgery, that she made a terrifying realization: “I didn’t know my friends.”

Kari, who is now 25 and wanted only her first name published, was later diagnosed with prosopagnosia, a condition often referred to as “face-blindness.”

Although her eyesight is perfectly fine, the surgery had damaged the part of her brain that uses visual cues to recognize faces, including those of her parents, younger brother and closest friends.

“I just see the general shape,” she said, “and I see the hair.”

While it was once believed to be rare, researchers now say about 2 per cent of the population may experience some degree of prosopagnosia. People can be born with the condition or acquire it through trauma or illness.

Inherited face-blindness has been studied for some time, and researchers say that new studies of acquired prosopagnosia may also help illuminate some of the most elusive inner workings of the brain, such as how it uses social cues.

Over the past year, Kari and others with acquired prosopagnosia have been travelling from across North America to Vancouver, where they undergo hours of testing as part of a new collaborative study group involving scientists from Canada and Europe.

Researchers hope the assessments will pinpoint which parts of the brain are involved in processing not only someone’s identity, but also their age, gender, emotions and whether or not they look physically attractive.

“If we can understand this, we can understand a lot about how the brain parcels out information and processes it,” said Jason Barton, a neuro opthamologist at the University of British Columbia who has studied the condition for eight years.

Others say studying the condition may help uncover the biological underpinnings of other cognitive disorders, including autism.

Prosopagnosia was first documented in 1947 by a German doctor who observed that a soldier who had suffered a bullet to the head had lost his ability to recognize people.

Until recently, the condition was believed to be very rare. But in the past couple years major studies have suggested that up to one in 50 people has some degree of face-blindness.

“I think it will become recognized as a real major malady or condition that causes people all kinds of trouble,” said Ken Nakayama, a professor at Harvard University’s psychology department whose research put the figure at around 2 per cent.

Entire article is here.