Study gives a jolt to brain researchers seeking to understand face blindness

At the push of a button, Dr. Josef Parvizi’s face melted. When Parvizi turned on the juice to two electrodes in his patient’s brain, “you just turned into somebody else,” the patient told the doctor from the hospital bed. “Your face metamorphosed. Your nose got saggy and went to the left. You almost looked like somebody I’ve seen before, but somebody different. That was a trip.”

Parvizi’s face wasn’t the only one that melted; a technician in the room also had the honor. “The bottom of her face sort of metamorphosized up, kind of stretched up to give her a different look,” the patient said of the woman’s face. “It wasn’t pretty.”

In an attempt to find the source of the man’s unrelenting seizures, doctors had implanted a web of electrodes that could listen for the start of a seizure and deliver a jolt to very precise targets. It turns out that two of these electrodes were sitting on pieces of prime face-recognizing real estate in the patient’s brain — parts of an area called the fusiform gyrus. Now, jolts to these two particular spots have helped settle a great brain debate.

Studies of the brain rarely offer clarity. At best, scientists have to say that a piece of the brain is “involved in” or “associated with” or “linked to” some function. For decades now, the fusiform gyrus has been involved in, associated with and linked to the perception of faces. But some scientists still weren’t satisfied. Just because neural activity peaks in that part of the brain when a person sees a face doesn’t necessarily mean that those nerve cells cause a person to perceive a face.

Now, with the man who saw faces melt, all this has changed. When the electrodes near those cells were switched on, the faces in the room looked strange. When the electrodes were off, everything went back to normal. Other things in the room, such as Parvizi’s suit and tie, the television and the words “Hope you’re feeling better” on a balloon, all escaped unscathed. The effect seemed to be specific to people’s faces. A fake stimulation round also didn’t cause the metamorphosis, scientists reported in the Oct. 24 Journal of Neuroscience.

The clear role of these two neural locations in face perception could help explain a mysterious condition known as face blindness, or prosopagnosia. In October, one of the world’s most famous prosopagnosiacs spoke via a video link to thousands of neuroscientists in New Orleans at the annual meeting of the Society for Neuroscience. Like neurologist Oliver Sacks and anthropologist Jane Goodall, artist Chuck Close has trouble perceiving faces. “I did not recognize a woman I lived with for a year two years later,” Close told attendees. “She was out of context — I knew her in Europe and I saw her in the United States. But believe me, that does not go over too well.”

Like the man compelled to see faces melt at the flip of a switch, Close perceives faces as disjointed pieces that are constantly changing. When he was sitting across from Stephen Colbert in 2010, Close told the host, “In real life, when you move your head a half an inch, to me, it’s a new face.”

Close has developed tricks to help him get by with minimal embarrassment. When he was teaching art students, he would sketch drawings of their artwork in a notebook next to their names. When it came time to grade them, he could identify the name based on the work. “I wouldn’t have recognized them on the street. I wouldn’t have recognized a photograph of them,” Close said. “But if I looked at their paintings, I remembered their paintings and I knew who they were.”

During his talk, Close walked listeners through how he produces his giant, intricate, bold portraits — of faces. Unlike many artists who mix colors on a palette, Close keeps it simple. He mixes paints on the canvas by doing multiple passes with different colors, subtly changing the hues with each sweep, as a printer would. Sometimes, he forms faces made up of grids of small squares, each containing its own abstract painting. This method presents a challenge when it comes to melding together all the small pieces to make a face. “I prefer to sneak up on what I want,” he said.

Although Close has been celebrated for his representations of faces on canvas, it’s not clear what keeps him from recognizing faces in real life. But the new results clearly show that the two clusters of nerve cells are involved and important. For the first time, scientists can claim that certain cells cause a person to perceive a face normally. And being able to use the word “cause” in studies of the brain is a big deal. For once, there is a rare sliver of clarity about how the brain perceives the world.

SN Prime | November 19 & 26, 2012 | Vol. 2, No. 44