Have you felt that you’ve already experienced something, even though you know you’re experiencing it for the first time? It’s unsettling and creepy, and around two-thirds of us have had déjà vu at some time. What is going on? Are we experiencing past lives, a glitch in the matrix or just a glitch in our own minds? It’s difficult to study a very brief feeling in a laboratory setting, but science does have some ideas on what causes déjà vu. A recent article published by Texas A & M University looks into what neuroscience thinks is happening.
Déjà vu means “already seen” in French. For most people it’s a harmless fleeting feeling. However, for some people with temporal lobe epilepsy, it can often be a sign that a seizure is coming. Many carers report that loved ones with dementia often state that they have been somewhere or experienced something before, despite this not being possible.
The temporal lobe area of the brain plays a key part in making memories. Certain parts of the temporal lobe are also used to detect familiarity. So it makes sense that something going wrong in this area could lead to the feeling of déjà vu. In the case of temporal lobe epilepsy something interferes with the normal firing of neurons, possibly due to scarring of the temporal lobe. In the case of dementia it may be due to degenerative brain cell damage.
In 2014, scientists studied a patient who suffered from persistent and debilitating déjà vu. Temporal Lobe Epilepsy was ruled out in this man’s case. His memory was functioning well and he was fully aware that the feeling of déjà vu was false. At first the feeling would last for minutes but started to intensify until he ended up experiencing déjà vu almost continuously. He even had to stop watching TV, listening to the radio and reading articles and books because the feeling that he had already seen, heard or read the material was so strong. In some ways he was robbed of novelty.
The scientists think that anxiety could be the cause of the patient’s symptoms. The hippocampus is a part of the temporal lobe and it is involved both in memory formation and in anxiety and depression.
To date this is the only case of anxiety being linked to déjà vu. But it is another clue that the problem lies in the temporal lobe.
What Causes Déjà Vu ?
“A déjà vu is usually a glitch in the Matrix. It happens when they change something” – Trinity, The Matrix, 1999
Many scientists refer to it as a glitch, though one in the brain and not in the dystopian Matrix. There is evidence that it could be caused by an electrical malfunction, or a mental short-circuit, if you prefer.
One possibility could be due to how the brain constructs an image of the world from limited sensory information. It takes short cuts. It could happen that a sound or smell (for example) could accidentally bypass short-term memory and activate long-term memory instead. And you feel like you’ve experienced this sensation before.
Also, visual processing is complex. When we see something the information passes through many pathways to different areas of the brain. These areas deal with thought, attention, awareness, language processing, perception and memory. It’s possible that one signal could be interpreted as two separate signals if the different parts of your brain do not process it at the same speed. So a hold-up in one area may be misinterpreted as seeing the same thing twice.
The brain interprets the second version, through the slowed secondary pathway—as a separate perceptual experience—and thus the inappropriate feeling of familiarity (déjà vu) occurs,” Michelle Hook, Neuroscientist at Texas A&M Health Science Center College of Medicine
So what causes déjà vu? It seems that it is nothing more than a brain fart. A temporary temporal glitch that signifies nothing more than a minor spooky inconvenience for the lucky majority. Memory formation is an area of brain function that is still not fully understood. As long as we don’t know how memory formation is supposed to work, we can only guess at what happens when it goes wrong. But, while we may not fully understand the causes yet, future research may help people who suffer from déjà vu on a more frequent basis.
If you’d like some more information on how the brain interprets the world from limited sensory input then you’ll like this – Yet You Do Not See?
Have you ever experienced déjà vu? Or does your brain work like a well-oiled machine?
Thanks for reading! If you like this post then please share and comment below but play nice! Abusive comments may be removed.