From Nature:
Ever struggled to recall something you knew you ought to remember? Part of the problem might be that your brain just wasn’t ready to store the memory in the first place. Neuroscientists have discovered that how successfully you form memories depends on your frame of mind not just during and after the event in question, but also before it. “People didn’t realize that what the brain does before something happens influences the memory of that event,” says Leun Otten of University College London, UK, who led the research. “They looked just at the response.”
But it turns out that if your brain is ‘primed’ to receive information, you will have less trouble recalling it later. Memory is aided by meaning.
More here.