Brain Stimulation Can Affect Which Hand You Favor

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Executive Health October 02, 2010, 09:00 EST text size: TT

Brain Stimulation Can Affect Which Hand You Favor

Further study might help victims of stroke and other brain injuries, researchers

say

HealthDay/ScoutNews LLC

SATURDAY, Oct. 2 (HealthDay News) --In what might one day help victims of stroke

and other brain injuries, researchers have found that the two sides of the brain

instantaneously 'negotiate' which hand to use for simple manual tasks.

That means, say the researchers, that before picking up a cup of coffee or

pushing an elevator button, the right and left sides of the brain -- each of

which controls the opposite appendage -- decide which hand is best suited for

the impending activity.

" By understanding this process, we hope to be able to develop methods to

overcome learned limb disuse, " study co-author Ivry, a University of

California, Berkeley, professor of psychology and neuroscience, said in a news

release.

Ivry and a team of Belgian, American and British colleagues report the findings

in this week's issue of the Proceedings of the National Academy of Sciences.

The team's observations stem from work with 33 right-handed volunteers, noting

that although 80 percent of people are right-handed, most are able to use either

hand to execute simple tasks that don't require fine motor skills.

All the participants allowed the posterior parietal cortex region of their

brains to be artificially activated by so-called transcranial magnetic

stimulation (TMS).

This brain region is integral in the processing of spatial relationships and

movement planning, the authors noted, and stimulating the area meant interfering

with the nerves that usually control motor skills.

By monitoring patient movement with a 3-D motion-tracking system and fingertip

sensors, the authors found that after applying TMS to the left side of the

right-handers' brains (which controls the motor skills of the right side of the

body), the participants favored the use of their left hand over their right.

The authors said that it remains unclear why the brain engages in such a

competitive decision-making process to begin with. But by doing this, " you're

handicapping the right hand in this competition, and giving the left hand a

better chance of winning, " study author Flavio Oliveira, a Berkeley postdoctoral

researcher in psychology and neuroscience, noted in the journal news release.

This demonstrated that TMS can be effective at brain manipulation, an

achievement that could ultimately be used to treat patients struggling with

motor control.

More information

For more on brain function, visit the National Institute of Neurological

Disorders and Stroke.

--Alan Mozes

SOURCE: Proceedings of the National Academy of Sciences, Sept. 27, 2010, news

release.

HealthDay.