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Hand Choice

November 3, 2010

Magnetically stimulating one part of the brain affects which hand people use for a task.


Competing hands…I’m Bob Hirshon and this is Science Update.

Like eager job applicants, your left and right hand compete to perform every mundane task, from turning a doorknob to scratching your nose. This according to neuroscientist Flavio Oliveira of the University of California at Berkeley. His team had right-handed volunteers reach for targets that appeared in different places in front of them. Then they repeated the task under the influence of magnetic brain stimulation, aimed at a particular region.

FLAVIO OLIVEIRA (University of California, Berkeley):
By stimulating this brain region, called the posterior parietal cortex, we managed to influence choice, and make people choose their left hand more often.

The region has previously has been linked to movement planning, and a condition called alien hand syndrome, in which the patient’s hand seems to act on its own. Olivera’s work suggests that our brains have to actively block one hand from doing the other one’s work. I’m Bob Hirshon, for AAAS, the science society.