printable versionMore than pretty faces for brain region, study finds
BY ADITI RISBUD
You'll find more than faces in these places.
Researchers have taken the closest look yet at a region of the brain that was thought to be devoted solely to face recognition and discovered that this particular patchwork of neurons does much more: It also responds to such objects as cars, animals and sculptures.
Current face-perception theories suggest neurons in a part of the brain, called the fusiform gyrus, light up in response to a face, leading researchers to refer to this region as the "fusiform face area." But a study in the September issue of Nature Neuroscience finds that this area also shows a localized, albeit less extensive, response to more than just faces.
"We've looked at the fine structure of face-selective regions in the brain, and it argues against prevailing theories," said senior author Kalanit Grill-Spector, PhD, assistant professor of psychology and a Neuroscience Institute researcher.
Using high-resolution functional magnetic resonance imaging, Grill-Spector and colleagues imaged brain regions at a resolution 27 to 70 times greater than a traditional fMRI scan. Like viewing a grain of sugar rather than the whole cube, this let the team "zoom in" on a hybrid of neural patches, each of which responds to a different category of objects. "We were able to see things we haven't before," she said. "What's really cool is these structures are very selective in their responses—and only to one kind of object."
The participants in the study were shown images of faces, four-legged animals, cars and abstract sculptures, along with scrambled images. The researchers found that overall, twice as many of the patches are predisposed to faces versus inanimate objects, and that the patches that respond to faces outnumber those that respond to animals by 50 percent. Furthermore, same-selectivity patches are not physically connected, implying a "face area" may not even exist.
"These results are exciting and suggest that the visual cortex contains finer category-selective subdivisions than previously believed," said Brad Duchaine, PhD, of the Institute of Cognitive Neuroscience at University College London, who was not involved in the research.
Co-author David Ress, PhD, associate professor of neuroscience at Brown University and a former research scientist at Stanford, explained: "It's no longer just a monolithic face-selective area. This suggests we need to take a step back and study smaller pieces of the brain first, or in addition to, the whole brain." More studies using this high-resolution technique are needed to properly categorize this region of the brain, he added.
Grill-Spector said: "This has implications for neuroscientists and psychologists. First, a new model has to explain how the brain recognizes faces and objects. To understand how it attaches meaning to a visual scene, scientists need to study both fine- and large-scale brain activity patterns. Second, it may be that what makes one individual exceptional in recognizing faces and another face blind are fine-scale differences in their brains' functional structure."
Along with Grill-Spector and Ress, neuroscience graduate student Rory Sayres worked on the study, which was funded by the National Eye Institute and the Whitehall Foundation.
Aditi Risbud is a science-writing intern in the Office of Communication & Public Affairs at the School of Medicine.