What Causes Déjà Vu?

Episodes of déjà vu may be closely related to how memory is stored in the brain.

Episodes of déjà vu may be closely related to how memory is stored in the brain. Retention of long-term memories, events and facts are stored in the temporal lobes, and, specific parts of the temporal lobe are also integral for the detection of familiarity, and the recognition of certain events. …

Instances of déjà vu in healthy individuals may also be attributed to a ‘mismatch’ in the brain’s neural pathways. This could be because the brain is constantly attempting to create whole perceptions of the world around us with limited input.

For example, it only takes a small amount of sensory information — like a familiar smell — for the brain to create a detailed recollection. Déjà vu could be linked to discrepancies in the memory systems of the brain, leading the sensory information to by-pass short-term memory and reach long-term memory instead. This may produce the unsettling feeling that we’ve experienced a new moment before.

Source: What causes déjà vu? – Science Bulletin