Year In Science

Sunday, January 13, 2002

Hope for Stroke Patients
A brain severely injured by stroke or other calamities may be more adaptable to recovery than previously thought. A neuroscience team led by Claus Hilgetag of Boston University's School of Medicine reported in September that temporarily knocking out one-half of the brain can boost the performance of the other half. Researchers fired focused magnetic pulses through the skulls of healthy volunteers for 10 minutes to temporarily induce hemispatial neglect, mimicking the damage caused by a brain lesion. "Magnetic stimulation gave us a window during which we could study modified behavior," says Hilgetag. With the left or right parietal cortex numbed, the test subjects were less able to detect objects placed in the visual field controlled by the numb side of their brain and did even worse still if there was also an object in the functioning half of the field. But they were better at spotting objects with the unaffected half of their brain. "Creating a lesion on one side seems to improve functioning in the unimpaired hemisphere," says Hilgetag. The findings suggest that normal mental activity results from a battle between the brain's many different areas, says Oxford psychologist Vincent Walsh. "We are familiar with this idea in daily life—you can excel at one skill only at the expense of others." Competition seems to be present at every level, from nerve cells to hemispheres, Walsh says. "It's challenging to think that all these brain regions could be working for themselves.
— Diane Martindale

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