Déjà Vu: What is the science behind this uncanny feeling of familiarity?

Sometimes, we experience a new event that gives us a rather creepy, eerie feeling of familiarity. We end up asking ourselves, “Hasn’t this happened before? Haven’t we already seen or heard this?” The whole experience seems like a flashback. Well, this sensation is what is popularly known as déjà vu, a French phrase meaning "already seen." In other words, it is an inexplicable feeling of familiarity that cannot be backed by evidence or logic. Déjà vu is an experience which combines our sense of familiarity with the knowledge that there is no explanation to ‘this all-too-known' or ‘already seen’ feeling. Though it is mostly described in terms of what one sees, a blind person can also experience déjà vu. This phenomenon is mostly associated with mystery and even the paranormal. But, can there be a scientific explanation to it? Well, a laboratory setting isn’t ideal for the study of this strange experience as it is a fleeting feeling. Also, there is no identified trigger behind it. However, scientists have tried to come up with some hypotheses with the help of some experiments. Here are a few possible explanations.  

Déjà vu could be a memory phenomenon 
One explanation to this theory is that déjà vu occurs when we come across a situation very similar to what we have experienced before and there is no conscious memory of the past event. However, we probably remember it in the unconscious layers of memory. Hence, the feeling of familiarity. There is another hypothesis which suggests that there is a possibility of déjà vu when people experience similar situations or are part of similar scenes in two different settings. Difference in the backdrop wipes away the memory of past experience.  

Déjà vu can have neurological explanations too 
Apart from the memory theories, there are other hypotheses behind the phenomenon of déjà vu. These are related to the functioning of our brain and nerves. Scientists claim that there are times when some spontaneous activities take place in parts of our brain dealing with memory. These have no connection with our current experience. This may lead to a false sense of familiarity.  

Temporal lobe is the part of our brain that regulates memory. People with temporal lobe epilepsy may experience déjà vu due to an abnormal electrical activity in this segment of the cerebrum.  

Another hypothesis links this phenomenon with information transmission from brain. A lot of information is transmitted and processed by the brain to help us make sense of the world around us. If this complex procedure is obstructed, resulting in abnormally slow or fast processing of information, our brain fails to interpret our surroundings appropriately. This may also lead to déjà vu.