- Connecting a battery across the front of the head can
boost verbal skills, says a team from the US National Institutes of Health.
-
- A current of two thousandths of an ampere (a fraction
of that needed to power a digital watch) applied for 20 minutes is enough
to produce a significant improvement, according to data presented this
week at the annual meeting of the Society for Neuroscience, held in San
Diego. And apart from an itchy sensation around the scalp electrode, subjects
in the trials reported no side-effects.
-
- Meenakshi Iyer of the National Institute of Neurological
Disorders and Stroke in Bethesda, Maryland, ran the current through 103
initially nervous volunteers. "I had to explain it in detail to the
first one or two subjects," she says. But once she had convinced them
that the current was harmless, Iyer says, recruitment was not a problem.
-
- The volunteers were asked to name as many words as possible
beginning with a particular letter. Given around 90 seconds, most people
get around 20 words. But when Iyer administered the current, her volunteers
were able to name around 20% more words than controls, who had the electrodes
attached but no current delivered. A smaller current of one thousandth
of an amp had no effect.
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- Trigger happy
-
- Iyer says more work needs to be done to explain the effect,
but she speculates that the current changes the electrical properties of
brain cells in the prefrontal cortex, the brain region through which it
passes. She believes that the cells fire off signals more easily after
the current has gone by. That would make the brain area, a region involved
in word generation, generally more active, she suggests.
-
- Iyer's group, which is led by Eric Wassermann, was prompted
to run the tests after considering problems facing researchers who were
studying the effect of magnetic fields on the brain. Some neuroscientists
hope that magnetic fields could have a therapeutic effect, perhaps by boosting
activity in areas of the brain that have suffered cell loss owing to dementia.
But magnetic fields can cause seizures and also require bulky equipment
to generate them.
-
- Iyer hopes that low electric currents will offer a safer
and more portable alternative. After running further safety tests, she
plans to test the effect of the current on patients with frontal temporal
dementia, a brain disease that causes speech problems. "This won't
be a cure," Iyer cautions. "But it could be used in addition
to drugs."
-
- The idea of using electrical current to boost brain activity
dates back to experiments on animals in the 1950s. The early work showed
some potential, but fell from favour because of a perceived link to electroconvulsive
therapy, a controversial technique in which patients with depression are
treated by having short but intense pulses of electricity applied to the
brain.
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- ©2004 Nature Publishing Group http://www.nature.com/news/2004/041025/full/041025-9.html
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