Brain Stimulation Can Affect Which Hand You
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 Richard 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.
For more on brain function, visit the
National Institute of Neurological Disorders and
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