SHANGHAI: Patient Number One is a thin man, with a scabby face and bouncy knees. His head, shaved in preparation for surgery, is wrapped in a clean, white cloth.

Years of drug use cost him his wife, his money and his self-respect, before landing him in this drab yellow room at a Shanghai hospital, facing the surgeon, who, in 72 hours, will drill two small holes in his skull and feed electrodes deep into his brain.