Neural Response is Specific for Face Perception

An area of the brain that activates when looking at faces does not respond the same way when perceiving other very familiar objects, according to a study by Yale researchers in the journal Neuropsychologia.

“We humans are all face experts,” said Yaoda Xu, associate research scientist in the Department of Psychology and first author of the study. “Face perception is crucial to social animals. We need to be able to recognize if another person is friendly or unfriendly, or recognize other emotions.”

Prior research has described a face–specific neural response that occurs about 170 milliseconds after an observer sees a face. The magnetic field generated by this neural response can be detected at the rear part of the human brain and is termed the M170 response. Xu and her colleagues wanted to know if the M170 response could be elicited by any visual stimuli that the observer has become an expert at, like cars for car experts.

The researchers had nine car experts look at images of cars, shoes and faces while measuring brain activity using magnetoencephalography, a brain scanning technology. The car experts and nine control subjects used as a basis of comparison all had a strong M170 response to faces. However, car stimuli did not elicit a higher M170 response in the car experts than it did in the control subjects. The researchers then had the car experts identify face and car images embedded in noise. While the success and failure of face identification strongly correlated with the amplitude of the M170 response, the success and failure of car identification did not.

“What this study showed is that the M170 sensor is face specific,” Xu said. “And this face specific response is not entirely due to our expertise with faces, but rather, it reflects a specialized neural mechanism in the brain dedicated to face processing.”

The research was conducted at the Massachusetts Institute of Technology under the direction of Nancy Kanwisher and with co–author Jia Liu of MIT. The research was supported by a National Eye Institute grant and by XuÕs McDonnell–Pew Investigator Initiated Grant in Cognitive Neuroscience.

Neuropsychologia 43: 588–597 (March 2005)

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