On a Sunday morning in a decaying and dangerous inner-city barrio in Lima, Peru, an unmarked white van carrying nearly a dozen bodies rumbles to a stop on the grounds of the National Institute of Neurological Sciences. Seated in a small waiting area to the rear of the building, a throng of well-dressed researchers and government officials watches intently. As the driver clambers out, an assistant hustles off in search of a hospital gurney. Within minutes, two men wheel the first body into the institute's imaging unit.