This experience is known to be novel, but has many recognisable elements, albeit in a slightly different setting. Related to this theory, it was proposed that déjà vu is a reaction of the brain’s memory systems to a familiar experience. This leads to the feeling of recognition without specific details. Other theories suggest activation of the rhinal neural system, involved in the detection of familiarity, occurs without activation of the recollection system within the hippocampus. This explains why a new experience can feel familiar, but not as tangible as a fully recalled memory. This implies déjà vu is evoked by a mismatch between the sensory input and memory-recalling output. That is, information bypasses short-term memory and instead reaches long-term memory. Some researchers speculate that déjà vu occurs due to a discrepancy in memory systems leading to the inappropriate generation of a detailed memory from a new sensory experience. Mismatches and short circuitsĭéjà vu in healthy participants is reported as a memory error which may expose the nature of the memory system. In people without epilepsy the vivid recognition combined with the knowledge that the environment is truly novel intrinsically underpins the experience of déjà vu. The déjà vu experienced prior to an epileptic seizure may be enduring, rather than a fleeting feeling in those who don’t have epileptic seizures. Some researchers argue that the type of déjà vu experienced by temporal lobe epilepsy patients is different from typical déjà vu. It has been proposed that déjà vu could be triggered by a similar neurological discharge, resulting in a strange sense of familiarity. An example of this is a hyponogogic jerk, the involuntary twitch that can occur just as you are falling asleep. These neuronal discharges can occur in a non-pathological manner in people without epilepsy. These observations led to the speculation that déjà vu is caused by a dysfunctional electrical discharge in the brain. It has been found that déjà vu is more readily induced in epilepsy patients through electrical stimulation of the rhinal cortices as opposed to the hippocampus. The brain regions in which this electrical activation can occur include the medial temporal lobes.Įlectrical disturbance of this neural system generates an aura (a warning of sorts) of déjà vu prior to the epileptic event.īy measuring neuronal discharges in the brains of these patients, scientists have been able to identify the regions of the brain where déjà vu signals begin. This dysfunctional neuronal activity can spread across the whole brain like the shock waves generated from an earthquake. This has given researchers a more experimentally controlled way of studying déjà vu.Įpileptic seizures are evoked by alterations in electrical activity in neurons within focal regions of the brain. Déjà vu occurs when the memory turns to them and forms a scene from one recovered detail.A subset of epilepsy patients consistently experience déjà vu at the onset of a seizure – that is, when seizures begin in the medial temporal lobe. Holographic theory: the memories that we have are deposited into so-called holograms.In this case, only the familiarity system would be activated, but not the information recall one. Double process theory: memory consists of two systems, and when déjà vu happens they desynchronize.
Psychoanalyst theory: the subconscious activates something that the person has imagined in the past, like a dream, or something they’ve seen somewhere before, like a place in a movie.Neurological theory: An electric shock is produced in the hippocampus or in the medial temporal lobe that causes the phenomenon to happen, which would explain why people with epilepsy have it before an attack.However, today studies have turned towards cognitive processes in the human brain and anomalies of memory to explain this phenomenon. In fact, Sigmund Freud and Carl Jung contributed their own explanations of déjà vu to the discussion: the former attributed it to repressed desires, and the latter to alterations of the collective unconscious. Cambiando el pasado (Changing the Past, movie)- Why does déjà vu occur?īetween the end of the 19th and beginning of the 20th century, psychoanalysis was one of the first psychological trends that tried to explain this mental phenomenon.