Looking into the brain's toolbox
The human brain includes more than 40 different areas devoted to vision. Nancy Kanwisher uses brain imaging and behavioral testing to study how these areas contribute to our perception of the visual world. Her lab has identified several regions of the brain that play specialized roles in the perception of specific categories of visual stimuli such as faces, places, and bodies. Kanwisher is also interested in understanding typical and atypical human brain development. She is heading an ambitious project to explore the origins of autism using new pediatric neuroimaging technologies.
Elements of perception
How is the task of analyzing the visual world divided between the many brain areas that are devoted to visual perception? Do they all work together on each visual task, like the components of a single general-purpose computer? Or is the brain more like a Swiss army knife, a package of separate tools, each specialized for a different job?
Kanwisher believes that the Swiss army knife model is a good one and that knowledge about different aspects of the visual world is embodied in distinct brain regions. Her work, which combines brain imaging with behavioral tests of human visual abilities, has led to the identification of distinct brain regions that are devoted specifically to perceiving faces, places, or body parts.
Kanwisher is interested in finding out whether these specializations are pre-determined by our genes or whether they arise as a result of experience. To address these questions, she has studied a brain area that responds to written characters and has found that it is indeed affected by experience. By comparing readers of English and Hebrew, she has found that this brain area responds preferentially to characters from a familiar language -- a clear example of how culture can shape the brain's perceptual responses.
Plasticity in development and disease
To further investigate the brain's plasticity, Kanwisher has collaborated with McGovern Institute colleague James DiCarlo to demonstrate changes in the brain when adults learn to recognize new and unfamiliar categories of objects. She is now extending her studies to children, in order to study how brain specializations arise during development and how they are shaped by a child's experiences.
Kanwisher will head an ambitious new project to study the origins of autism, supported by a grant from the Ellison Medical Foundation. Brain imaging with young children presents many challenges, not least of which is their inability to lie still for long periods in the scanner. Kanwisher will collaborate with neuroimaging experts Larry Wald, Bruce Fischl and Ellen Grant at Massachusetts General Hospital (MGH), who will develop scanning coils designed specifically for children's heads, along with new procedures to shorten scan times and methods to analyze data from brains that are not yet fully developed. "We expect these technological advances to radically improve pediatric neuroimaging and help us make major strides in understanding typical and atypical human brain development," Kanwisher says.
Kanwisher has also shown that macular degeneration, the leading cause of blindness in Western societies, leads to extensive reorganization of the visual part of the brain. Macular degeneration is a progressive disease of the retina, and understanding the brain changes that accompany this degeneration may be important in devising new treatments for the disease.
Nancy Kanwisher is the Walter A. Rosenblith Professor of Cognitive Neuroscience in the Department of Brain and Cognitive Sciences and a founding member of the McGovern Institute. She joined the MIT faculty in 1997, and prior to that served on the faculty at UCLA and Harvard University. In 1999, she received the National Academy of Sciences Troland Research Award. She was elected to the National Academy of Sciences in 2005 and to the American Academy of Arts and Sciences in 2009.
Image: Kent Dayton