An overview of déjà vu

Explaining what déjà vu is and a very brief review over scientific findings and speculation concerning the déjà vu experience.

1. An Overview of Déjà Vu Scientific findings and speculation concerning the déjà v u experience 1

2. What am I going to talk about? 2

3. What is déjà vu? 3

4. A definition Déjà vu is that feeling when you experience something familiar, but in fact it is novel. “We have all some experience of a feeling which comes over us occasionally, of what we are saying or doing having been said or done before, in a remote time – of our having been surrounded, dim ages ago, by the same faces, objects and circumstances – of our knowing perfectly what will be said next, as if we suddenly remembered it” ( Dickens 1849 ). Standard definition : Any subjectively inappropriate impression of familiarity of a present experience with an undefined past. 4

5. Facts Lifetime Incidence : Everybody experiences at least one déjà vu in his/her lifetime. Not Frequent : Healthy brains do not experience it very frequent. Decreases with Age : It starts from 8-9 and mostly happens when you are young. Education : Happens more to better educated people. Travel : There would be lots of new physical locations and logically, more chance of déjà vu. Fatigue : Déjà vu experiences are more likely when fatigued. Brain illness : Déjà vu can be associated with some brain illnesses. 5

6. What causes déjà vu? 6

7. Problems in finding the causes 7

8. Some scientific explanations There are lots of explanations, but none is certain. They fall into four categories: Dual-processing explanations. Neurological explanations. Memory explanations. Attentional explanations . We will have a quick brief over them. 8

9. Some scientific explanations 9

10. Dual-Processing Explanations This explanations assume that two cognitive processes that normally operate in synchrony become momentarily uncoordinated or out of phase. 10 Novel experience Perception Memorizing 2 1 Retrieve Novel experience Perception Memorizing 1 2 Retrieve Normal Déjà vu An example of dual-Processing explanations. 1 and 2 show precedence 1

11. 11 Neurological explanations Suggest that déjà vu represents a brief dysfunction in the nervous system involving either a small seizure or alteration in the normal time course of neuronal transmission. 2 EEG results of a patient with TLE. Déjà vu is part of the preseizure aura in some TLEs. A logical extension is that d éjà vu in nonepileptic individuals results from a small temporal lobe seizure TLE = Temporal Lobe Epilepsy EEG = Electroencephalography

12. 12 Memory explanations Memory interpretations assume that some aspect of the present setting is objectively familiar but that the source of familiarity has been forgotten. 3

13. 13 Attentional explanations Attentional interpretations posit that an initial perception under distraction is followed immediately by a second perception under full attention. 4 Distracted (Pay attention to the music) Immediately after that - Paying attention to the scene

14. Brain parts involved in déjà vu According to scientific explanations, many parts of the brain can be involved in this phenomenon. Temporal Lobe has been studied in many literature, since: Frequent déjà vu experience with longer duration is reported in patients with Temporal Lobe Epilepsy (TLE). Hippocampus which plays important role in consolidating information and memorizing is in Temporal lobe. Any malfunction of Hippocampus can have a role in experiencing déjà vu. 14

15. Final words Although everybody experiences déjà vu during his/her life, still there’s no dominant explanation for this phenomenon. Temporal lobe may be the part of the brain in which déjà vu can be triggered from. In W eek 10, Module 1 to 3, Prof. Mason talks a little about attention in “Thalamic Attention” lecture and she talks about Temporal lobe and Hippocampus in “ The Story of H.M.” and “Memory Formation Circuitry” lectures. Her notes about “implicit Perceptual Memory” in “Memory Types” lecture somehow can be used in attentional interpretations of déjà vu. They all helped me understand listed explanations about déjà vu. 15

16. 16 Thank You

17. References Mainly from: Brown, Alan S. "A review of the déjà vu experience." Psychological bulletin 129.3 (2003): 394. Other resources: Warren-Gash, Charlotte, and Adam Zeman. "Deja vu." Practical Neurology 3.2 (2003): 106-109. Vlasov, P. N., A. V. Chervyakov, and V. V. Gnezditskii. "Déjà vu phenomenon-related EEG pattern. Case report." Epilepsy & Behavior Case Reports 1 (2013): 136-141. See also: https:// www.youtube.com/watch?v=CSf8i8bHIns https:// www.youtube.com/watch?v=foVMwJtlR5s 17