An anonymous reader writes from an article on MedicalXpress: They say that once you've learned to ride a bicycle, you never forget how to do it. But new research suggests that while learning, the brain is actively trying to forget. "This is the first time that a pathway in the brain has been linked to forgetting, to actively erasing memories," says Cornelius Gross, who led the work at EMBL. At the simplest level, learning involves making associations, and remembering them. Working with mice, Gross and colleagues studied the hippocampus, a region of the brain that's long been know to help form memories. Information enters this part of the brain through three different routes. As memories are cemented, connections between neurons along the 'main' router become stronger. When they blocked this main route, the scientists found that the mice were no longer capable of learning a Pavlovian response -- associating a sound to a consequence, and anticipating that consequence. But if the mice had learned that association before the scientists stopped information flow in that main route, they could still retrieve that memory. This confirmed that this route is involved in forming memories, but isn't essential for recalling those memories. The latter probably involves the second route into the hippocampus, the scientists surmise. But blocking that main route had an unexpected consequence: the connections along it were weakened, meaning the memory was being erased.