Memory

On the surface, memory doesn't seem to be a complicated concept. When we encounter something, our brains store it as learned knowledge that may be retrieved at a later time if necessary. Unless we are deliberately forcing our brain to retain certain information for a specific later use, such as when studying for a test, the process is virtually entirely unconscious.

Memory recall is one of the greatest mysteries in neuroscience, and while the process of storing memories is fairly well understood, we simply do not understand how the brain retrieves that information (which is saying a lot, as the brain has a lot of other mysterious features).

Except for the hippocampus, where we know new memories are encoded when they are generated, we have no idea what happens in the brain whenever the frontal cortex sends a signal intended to retrieve a specific memory or even what areas of the brain are used in the process.