WASHINGTON, D.C.--Is a part of the brain reserved especially for recognizing locations, such as rooms, streets, and landscapes? Yes, suggests a study presented here on 18 February at the annual meeting of the American Association for the Advancement of Science, which publishes ScienceNOW.
Scientists already know that there's a special place in the brain's visual cortex--known as the fusiform face area--that helps recognize faces. Now cognitive scientist Nancy Kanwisher and postdoc Russell Epstein, both at the Massachusetts Institute of Technology, claim that evolution may have put an equally high value on the ability to recognize landscapes and enclosed places such as caves.
Kanwisher studied a group of healthy adults with functional magnetic resonance imaging. In each of several dozen subjects, a small area in the visual cortex that Kanwisher calls the parahippocampal place area (PPA) appeared to be especially responsive to a series of pictures of rooms or landscapes. It was clearly a response to places, she says; if all a room's furnishings were shown without the floors and walls, the PPA did not respond more than the rest of the brain, but a bare room did activate the area. What's more, if the researchers presented a fragmented picture containing unconnected images of the wall, floor, and ceiling of the bare room, there was no increased activation in the PPA.
Kanwisher and postdoc Paul Downing also showed the volunteers images of other objects for which specialized brain areas might exist, such as predatory animals and food plants, as well as things for which evolution would not have prepared the brain, such as automobiles and musical instruments. "None produce anything like the specialized response for faces and spaces," said Kanwisher. The PPA lighted up even when subjects were only imagining places, she added.
Kanwisher is getting what are "probably the most interesting results in the field," says Harvard psychologist Alfonso Caramazza. But, he cautions, the work "doesn't mean there are not specialized brain responses to other categories." For instance, he says, studies of brain-damaged patients have shown that recognition of animals can be selectively damaged. Perhaps that specialization resides not in a particular region but in a brain circuit, says Caramazza.