See it, imagine it -- it's the same to your brain

WASHINGTON (Reuters) -- Imagining something and actually seeing it are virtually one and the same to the brain, researchers said Wednesday.

They said the same parts of the brain light up when a person thinks of a face or a scene as when the same person actually looks at a photograph of the same face or place.

And, the team at the Massachusetts Institute of Technology reports, they can tell, with 85 percent accuracy, whether a person is thinking of a face or a place, just by looking at how his or her brain lights up.

"We use some of the same brain machinery when we actively see and when we simply imagine," Nancy Kanwisher, associate professor of brain and cognitive sciences at MIT, said in a statement.

Writing in the Journal of Cognitive Neuroscience, Kanwisher and Kathleen O'Craven of the Rotman Research Institute in Toronto, Canada said they used functional magnetic resonance imaging (fMRI) to look at the brains of volunteers.

FMRI allows researchers to see blood flow and activity in various parts of the brain in real time.

"These findings strengthen evidence that imagery and perception share common processing mechanisms and demonstrate that the specific brain regions activated during mental imagery depend on the content of the visual image," the researchers wrote in their report.

Kanwisher and colleagues had, in previous studies, identified a part of the brain's cortex called the parahippocampal place area, which responded strongly to images of indoor and outdoor spaces, but not at all to faces.

Another cortical region, called the fusiform face area, responded strongly to images of faces.

In their latest study they concentrated on these two areas as they asked volunteers to look at photographs of places or faces and then to later create, with their eyes closed, a mental image of the same faces and scenes.

The fMRI images "reveal a striking similarity between regions activated during imagery and those activated during perception," they wrote.

Finally, the researchers checked to see if, simply by looking at the fMRIs, they could tell whether a person was thinking of a face or a place, and found they were correct 85 percent of the time.

Copyright 2000 Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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