Déjà-vu is a feeling of having been somewhere before though (to one’s knowledge) they have never.
The prefrontal cortex is responsible for most high-level processes in the brain, and is generally thought to contain such subjective things as, morality, self control, self awareness, and many others. Evolutionarily the purpose of such a highly advanced neuro-network is theorized to be event prediction. For example, in order to accurately spear an animal well it is running, one must predict where it will be in relation to how long it will take for the spear to travel from ones self to the animal. If we did not process that the animal is moving at such a speed, and compensated for it, our ancestors would most likely have died quite a long time ago. As anyone who has played sports can tell you, hand eye coordination becomes subconscious at times, and the player is able to catch a ball or throw without any conscious processing.
I believe déjà-vu to be a link between our subconscious continual predictions on every day circumstances, and our conscious experience of these things. Though we cannot tap into our subconscious mind, it is not a far leap to conclude its role in attempting to predict future circumstances so as to protect ourselves from lack of water, food, or social persecution. Thus our unconscious must also attempt to predict our environments through which we must acquire our necessities.
Though I am presenting a lack of scientific evidence, and knowledge of research put into such a phenomena, I feel it is a simple explanation for something that is often misconstrued as proof of the paranormal or metaphysical realms.
