In DepthNeuroscience

Cadaver study challenges brain stimulation methods

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Science  22 Apr 2016:
Vol. 352, Issue 6284, pp. 397
DOI: 10.1126/science.352.6284.397

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Summary

Earlier this month, György Buzsáki of New York University in New York City showed a slide that sent a murmur through an audience in the Grand Ballroom of New York's Midtown Hilton during the annual meeting of the Cognitive Neuroscience Society. It wasn't just the grisly image of a human cadaver with more than 200 electrodes inserted into its brain that set people whispering; it was what those electrodes detected—or rather, what they failed to detect. When Buzsáki and his colleague, Antal Berényi of the University of Szeged in Hungary, mimicked an increasingly popular form of brain stimulation by applying alternating electrical current to the outside of the cadaver's skull, the electrodes inside registered little. Hardly any current entered the brain. On closer study, the pair discovered that up to 90% of the current had been redirected by the skin covering the skull, which acted as a "shunt," Buzsáki said. For many meeting attendees, the unusual study heightened serious doubts about the mechanism and effectiveness of transcranial direct current stimulation, an experimental, noninvasive treatment that uses electrodes to deliver weak current to a person's scalp or forehead.