Miami Beach, Oct. 24, 1999 -- Using a novel approach to imaging, researchers have discovered that thinking about moving objects pre-activates areas of the brain's motion detection system before any moving objects appear. These areas would hold our expectations on-line as we prepare to cross a busy street, return a tennis serve or catch a falling child.
"This pre-activation may tune the motion detection pathway, allowing us to respond more strongly and selectively when an anticipated object appears," says Gordon L. Shulman, Ph.D., research scientist in neurology at Washington University School of Medicine in St. Louis.
Shulman and colleagues report their findings in the November issue of the Journal of Neuroscience. They will discuss additional experiments Oct. 24 and 26 during the annual meeting of the Society for Neuroscience in Miami Beach, Fla. "You could use this method anytime you wanted to separate the processes that prepare you to do a task from those involved in executing that task," Shulman says.
A major stumbling block has hampered attempts to understand how cognitive expectations such as goals, memories and thoughts influence the way we see the world. Because images obtained through positron emission tomography (PET) could not be made in less than 40 seconds, they merged expectation with perception. But the advent of functional magnetic resonance imaging (fMRI) cut the time scale to a few seconds. Using BOLD fMRI, Shulman and colleagues have devised a way to obtain separate images of expectation and perception during a single trial. For example, they can obtain one set of images while a person anticipates a visual stimulus and a second set when the stimulus appears.
"This enhanced precision in human neuroimaging allows us to track the
sequential involvement of different areas of the brain at different times during
a task," says co-author Maurizio Corbetta, M.D., assistant professor of
Contact: Linda Sage
Washington University School of Medicine