We all know the iconic “Do you get déjà vu, huh?” from songwriter Olivia Rodrigo– lyrics directed at her ex-boyfriend and his new girlfriend. Even if you haven’t experienced a similar situation, déjà vu is a common experience among many; an estimated 97% of people have experienced it at least once, and 67% experience it regularly.
Déjà vu means “already seen” in French– it refers to the unsettling feeling of having experienced a situation before, even when it is happening for the first time. Despite being a shared experience, the neuroscience behind this intriguing experience remains a subject of debate and ongoing research. This article aims to delve into the intricate workings of the human brain to unravel the mysteries behind déjà vu.
What does Déjà Vu feel like?
This phenomenon is difficult to understand through definitions, so let’s use an analogy.
Say you’re having a picnic at the park with your friends. Eating sandwiches, listening to music, sharing laughs– but suddenly, out of nowhere, you feel like this whole scene happened? The scenery, the people, the song being played on your friend's phone are all the same. But try as you might, you can't pinpoint when or where you experienced this. The sense of déjà vu similarly leaves you in a momentary haze, as if navigating a mental photo album where the borders between past and present blur.
Neural Basis of Memory
To comprehend déjà vu, it is essential first to understand the neural mechanisms underlying memory. Memories involve a network of interconnected regions, such as the hippocampus and the prefrontal cortex. Encoding, storing, and retrieving memories is a dynamic dance of chemical signals between these regions. It is widely thought that déjà vu occurs when there is a temporary disruption in the brain’s memory retrieval process– and many scientific theories attempt to address the neurology behind it.
However, there are two prominent theories: Dual Processing and the Hologram Theory.
Theory 1: Dual Processing
Déjà vu is often explained through the disruption of cognitive memory operations through the dual process theory, where the brain uses two distinct processes for storing and retrieving information. Read this article for more information.
We must first consider the role of two memory retrieval processes: recollection and familiarity. The recollection process retrieves information based on a threshold process, while the familiarity process gauges the perceived familiarity of an experience through a signal detection process. At times, only the familiarity process is active, causing a sense of familiarity without identifying its source due to the inactive recollection function. Though further neurological research is needed, this theory offers a logical model for understanding the phenomenon of déjà vu.
Theory 2: Hologram Theory
According to the hologram theory, memories are stored as patterns of neural activations throughout the brain– this suggests that encountering a single factor in an environment similar to one of these neural activations will activate the entire pattern of neural activations, generating a feeling of familiarity. This theory suggests there are holographic connections to your previous memories and present experiences.
Is Déjà Vu Normal?
This phenomenon is not inherently damaging or unhealthy. However, more people are susceptible to experiencing it than others, and it is said that it happens more frequently to individuals who:
Have a high level of education
Travel frequently
Remember their dreams
Hold liberal beliefs
Déjà vu can also be a sign of underlying health concerns if other symptoms, like loss of awareness, seizures, etc, accompany them. In some cases, it can also be a symptom of temporal lobe epilepsy, epilepsies originating in the temporal lobe. Hence, if you are experiencing frequent déjà vu and many other symptoms, you may want to consider visiting a doctor to be evaluated for other possible neurological conditions.
Reference list
Bosnjak Pasic, M., Horvat Velic, E., Fotak, L., Pasic, H., Srkalovic Imsiragic, A., Milat, D., Sarac, H., Bjedov, S. and Petelin Gadze, Z. (2018). MANY FACES OF DÉJÀ VU: A NARRATIVE REVIEW. Psychiatria Danubina, 30(1), pp.21–25. doi:https://doi.org/10.24869/psyd.2018.21.
Cleveland Clinic (2018). Temporal Lobe Epilepsy | Cleveland Clinic. [online] Cleveland Clinic. Available at: https://my.clevelandclinic.org/health/diseases/17778-temporal-lobe-seizures.
Cleveland Clinic. (n.d.). Why Does Déjà Vu Happen? [online] Available at: https://health.clevelandclinic.org/deja-vu-what-it-is-and-when-it-may-be-cause-for-concern.
Dumper, K., Jenkins, W., Lacombe, A., Lovett, M. and Perimutter, M. (n.d.). 8.2 Parts of the Brain Involved in Memory – Introductory Psychology. [online] opentext.wsu.edu. Available at: https://opentext.wsu.edu/psych105/chapter/8-3-parts-of-the-brain-involved-in-memory/#:~:text=The%20main%20parts%20of%20the.
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