NYU's electrode (represented in red) fits through tiny capillaries. (Courtesy of Rodolfo Llinas)

To treat severe cases of Parkinson's disease, surgeons implant electrodes deep in the brain, where they deliver high-frequency electrical pulses that shut down neural systems responsible for the disease's characteristic tremors. But this expensive treatment, called deep brain stimulation, is risky: the patient's skull must be opened, and the electrodes can damage blood vessels in the brain.

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