Mrs. Lancaster: I don't think so, but I could check with the kitchen [1].
I hate to admit it, but I don't know anything about déjà vu. However, I believe that it is: 1) something that has happened to most of us; and 2) a completely fascinating subject in its own right. Like me, you might be wondering: What causes déjà vu?
In the movie The Matrix (1999), déjà vu was explained as, "a glitch in the matrix." In other words, "they" (i.e., the system administrators) changed something. That's all well and good for people who inhabit a computer simulation, but what about people in real life? Is there another explanation?
Philip K. Dick's Electric Dreams: Season 1, Episode 1 "Real Life"
There's an alternative explanation that that recently came up in a sci-fi television show, but sounded like it was based in sci-nonfi(ction). According to the first episode of Electric Dreams ("Real Life"), déjà vu is result of two normal cognitive functions: perception and memory [2]. In this episode, George, the main character, owns a company that produces virtual reality (VR) headsets. Unfortunately, he hit his head extremely hard. To deal with his current situation, he does two things. He uses a VR prototype to help him process what happened. In an unusually gripping VR experience, he is left wondering what is real and what is virtual. In addition to treating himself with technology, he contacts his personal doctor, Paula. Here is their dialog:Paula: There's a theory that what we call déjà vu is actually a delay in real-time information being transmitted from one hemisphere of the brain to the other. That lag is only microseconds, but when it's received in the second hemisphere, it creates a small, momentary dissonance in perception. Now, that dissonance is misinterpreted by the cerebral cortex as memory, so the mind believes that normal events have been experienced twice.
George: Yeah, but this isn't déjà vu. It's like the memories have been there all along.
Paula: Well, they are memories, but they're memories of simulated events, events from your VR program. I think your brain's having trouble processing these simulated events, and it's creating a dissonance in your cerebral cortex, just like déjà vu.
George: I tell you it feels much more real than that. I keep having these flashes of that life, and I swear, it feels right. Feels true.
According to Paula, déjà vu is a result of delayed signals traversing the corpus callosum, which is a thick band of neurons that connect the left and right hemispheres [3]. I know the show is fiction, but how good is its explanation for déjà vu?
To evaluate Paula's theory, I consulted two resources. The first, Psychology Today, is a publication geared toward non-specialists, while the second, Neuron, publishes cutting-edge neuro-scientific research. Psychology Today returned 275 hits when I searched for "déjà vu" (mostly in the form of blog entries), and Neuron had exactly three articles with those search terms. These results tell me that this is an extremely popular topic without many studies devoted to uncovering the neuroscientific underpinnings of the phenomenon. Despite that fact, I found a small amount of evidence for the idea that there are brain systems that are out of sync [4]. For example, one study claimed that individuals who suffer from "complex partial seizures" experience hallucinations and déjà vu. They hypothesize that seizures disrupt memory and perceptual neural networks by causing them to be temporarily unsynchronized [5].
In addition to the asynchrony explanation, there is another piece that seems to fit with current findings in cognitive psychology. George reports that his experiences are authentic and feel "real" and "true." I find that interesting given the research on source monitoring. In a previous post, we discussed how people can convince themselves that they were the source of an idea, only to find out later that they picked up the idea from someone else.
Maybe there's something to the déjà vu theory put forth in Electric Dreams. But anyway you slice it, be sure you don't jeopardize recovering from a concussion with too much VR. Otherwise, you'll be staying at Mrs. Lancaster's Bed & Breakfast for a very...long...time.
Share and Enjoy!
Dr. Bob
More Material
[1] Dialog from the movie Groundhog Day (1993). The main character wakes up and experiences the exact same morning routine as the day before.[2] Special thanks to Springfield! Springfield! for the transcript of "Real Life". Watch Electric Dreams on Amazon Prime.
[3] If you want to read about some really freaky stuff, checkout what happens when patients have their corpus callosum severed, effectively creating individuals with two separate brains.
[4] Uhlhaas, P. J., & Singer, W. (2006). Neural synchrony in brain disorders: relevance for cognitive dysfunctions and pathophysiology. Neuron, 52(1), 155-168.
[5] Medvedev, A. V. (2002). Epileptiform spikes desynchronize and diminish fast (gamma) activity of the brain: an “anti-binding” mechanism? Brain Research Bulletin, 58(1), 115-128.
