[Niraj]

Dejavu phenomenon is an established symptom of temporal lobe seizures.It is thought to be the result of faulty and isolated activity of a recognition memory system that consists of the parahippocampal gyrus and its neocortical connections. This memory system is responsible for judgments of familiarity.
The result is that a momentary perceived scene is given the characteristics of familiarity that normally accompany a conscious recollection. The normal functioning of other brain structures involved in memory retrieval—the prefrontal cortex and the hippocampus proper—leads to the perplexing phenomenological quality of déjà vu.