Scientists can run invasive studies of the human brain only in special cases. Medical devices implanted to assess or treat certain conditions offer the chance to gather additional data for research. Listening in on neurons at close range can yield basic insights into brain function. Awake surgeries to insert such devices or resect tumors can sometimes be paused briefly for an unrelated experiment. Fried estimates roughly 30 groups in North America now do intracranial human neuroscience in epilepsy surgery patients—up from fewer than 10 when he started in the field, about 20 years ago. Researchers can also tap into therapeutic devices that stay in the brain long-term, some of which both deliver electrical stimulation and read out neural activity. Such implants are still underused sources of neural data, says UC Los Angeles (UCLA) neuroscientist Nanthia Suthana, who has used their recordings to study learning, memory, and spatial navigation. Another rare opportunity comes from people w

  A US man has become the first person in the world to get a heart transplant from a genetically-modified pig. David Bennett, 57, is doing well three days after the experimental seven-hour procedure in Baltimore, doctors say. The transplant was considered the last hope of saving Mr Bennett's life, though it is not yet clear what his long-term chances of survival are. "It was either die or do this transplant," Mr Bennett explained a day before the surgery. "I know it's a shot in the dark, but it's my last choice," he said. Doctors at the University of Maryland Medical Center were granted a special dispensation by the US medical regulator to carry out the procedure, on the basis that Mr Bennett - who has terminal heart disease - would otherwise have died. He had been deemed ineligible for a human transplant, a decision that is often taken by doctors when the patient is in very poor health. The pig used in the transplant had been genetically modified to kno