The United States has decided not to grant travel visas to about 70 medical professors, doctors and researchers planning to attend a symposium on brain injury in Havana, Cuba. About 200 attendees from around the world were expected at the conference. This is the fourth symposium held in Havana, and U.S. attendees have not had any prior interference from the State Department. This year, however, the government contacted the tour company handling the researchers’ travel arrangements and requested additional information about the symposium, after which the Americans were barred from going.