The ability to recognize faces is so important in humans that the brain appears to have an area solely devoted to the task: the fusiform gyrus.

Brain imaging studies consistently find that this region of the temporal lobe becomes active when people look at faces. Skeptics have countered, however, that these studies show only a correlation, but not proof, that activity in this area is essential for face recognition. Now, thanks to the willingness of an intrepid patient, a new study described online in the Journal of Neuroscience provides the first cause-and-effect evidence that neurons in this area help humans recognize faces -- and only faces, not other body parts or objects.

An unusual collaboration between researchers and an epilepsy patient led to the discovery. Ron Blackwell, an engineer in Santa Clara, California, came to Stanford University in Palo Alto, Calif., in 2011 seeking better treatment for his epilepsy. He had suffered seizures since he was a teenager, and at age 47, his medication was becoming less effective. Neurologist Josef Parvizi suggested some tests to locate the source of the seizures because it might be possible to eliminate the seizures by surgically destroying a tiny area of brain tissue where they occurred.

Parvizi used electrodes placed on Blackwell's scalp to trace the seizures to the temporal lobe. When Parvizi sent a signal through electrodes on the fusiform gyrus, Blackwell told him, "You just turned into somebody else. Your whole face just sort of metamorphosed." When the stimulation was stopped, Blackwell reported that Parvizi's face had "returned" to normal. It also caused Blackwell to perceive distortions in the face of Parvizi's assistant. It did not produce changes in Parvizi's suit or in objects in the room.

Teaming up with Stanford neuroscientist Kalanit Grill-Spector, he scanned Blackwell's brain using functional magnetic resonance imaging and confirmed that the two electrodes that influenced Blackwell's perception of faces were at points in the fusiform gyrus implicated by Grill-Spector's previous research.

SCIENCENOW

CPR USE MAY DEPEND ON NEIGHBORHOOD

If your heart stops and you fall to the ground, your chances of survival may depend on which neighborhood you're in when you collapse.

Patients suffering cardiac arrest in poorer, predominantly black neighborhoods were half as likely to receive CPR from a bystander as those in richer, predominantly white neighborhoods, said research in the New England Journal of Medicine.

Even cardiac arrest victims in well-to-do black neighborhoods were 23 percent less likely to receive bystander assistance. And overall, blacks and Latinos were less likely to receive aid, regardless of where they were, said Dr. Comilla Sasson, an emergency medicine physician at the University of Colorado School of Medicine in Aurora, who led the study.

Sudden cardiac arrest outside a hospital is the leading cause of death in the United States, killing about 300,000 people annually. Sudden cardiac arrest is caused by an electrical glitch that prompts an abnormal heart rhythm and is different from a heart attack, which happens when blood flow is blocked and a region of the heart is starved of oxygen. About 92 percent of people who suffer sudden cardiac arrest die.

This is where CPR comes in. Those first few minutes after a person's heart malfunctions, but before an ambulance arrives and emergency medical responders take over, can mean all the difference for survival. But survival rates vary widely from city to city. In places such as Seattle, the rate is 16 percent. In Detroit, it's 0.2 percent.

LOS ANGELES TIMES