It's long been known that traumatic memories forged in stressful situations can lie buried in the subconscious, yet they can bubble to the surface unexpectedly, triggering strong reactions, flashbacks and more serious psychological problems such as post-traumatic stress disorder, or PTSD. Researchers have discovered that memories made under such conditions - or under the effects of drugs or alcohol - tend to only be recalled when a person is back in that state again: something known as state-based learning. By putting mice under the influence of a drug called gaboxadol, a team of scientists... Like this podcast? Please help us by supporting the Naked Scientists