Unveiling the mystery of déjà vu: The structural anatomy of déjà vu

Non-ictal, interictal and ictal déjà vu: a systematic review and meta-analysis

Background

Déjà vu, French for "already seen," is a phenomenon most people will experience at least once in their lifetime. Emerging evidence suggests that déjà vu occurs in healthy individuals (as "non-ictal déjà vu") and in epilepsy patients during seizures (as "ictal déjà vu") and between seizures (as "interictal déjà vu"). Although the ILAE has recognized déjà vu as a feature of epileptic seizures, it is notably absent from the ICD-11. A lack of evidence-based research may account for this omission. To our knowledge, this study represents the first systematic review and meta-analysis on déjà vu experiences. Through detailed examinations of non-ictal, interictal and ictal déjà vu, we seek to highlight possible clinical implications. Rethinking the status quo of ictal déjà vu could potentially lead to earlier interventions and improve outcomes for epilepsy patients.

Methods

This study was registered in PROSPERO (ID: CRD42023394239) on 5 February 2023. Systematic searches were conducted across four databases: EMBASE, MEDLINE, PsycINFO, and PubMed, from inception to 1 February 2023, limited to English language and human participants. Studies were included/excluded based on predefined criteria. Data was extracted according to the PICO framework and synthesized through a thematic approach. Meta-analyses were performed to estimate prevalence's of the phenomena. Study quality, heterogeneity, and publication bias were assessed.

Results

Database searching identified 1,677 records, of which 46 studies were included. Meta-analyses of prevalence showed that non-ictal déjà vu was experienced by 0.74 (95% CI [0.67, 0.79], p < 0.001) of healthy individuals, whereas interictal déjà vu was experienced by 0.62 (95% CI [0.48, 0.75], p = 0.099) and ictal déjà vu by 0.22 (95% CI [0.15, 0.32], p = 0.001) of epilepsy patients. Examinations of phenomenological (sex, age, frequency, duration, emotional valence, and dissociative symptoms) and neuroscientific (brain structures and functions) data revealed significant variations between non-ictal, interictal and ictal déjà vu on several domains.

Conclusion

This systematic review and meta-analysis do not support the notion that non-ictal, interictal and ictal déjà vu are homogenous experiences. Instead, it provides insight into ictal déjà vu as a symptom of epilepsy that should be considered included in future revisions of the ICD-11.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=394239, CRD42023394239.

Towards a conflict account of déjà vu: The role of memory errors and memory expectation conflict in the experience of déjà vu

Déjà vu can be defined as conflict between a subjective evaluation of familiarity and a concurrent evaluation of novelty. Accounts of the déjà vu experience have not explicitly referred to a "conflict account of déjà vu" despite the acceptance of conflict-based definitions of déjà vu and relatively recent neuroimaging work that has implicated brain areas associated with conflict as underpinning the experience. Conflict monitoring functioning follows a similar age-related trajectory to déjà vu with a peak in young adulthood and a subsequent age-related decline. In this narrative review of the literature to date, we consider how déjà vu is defined and how this has influenced the understanding of déjà vu. We also review how déjà vu can be understood within theories of recognition memory and cognitive control. Finally, we summarise the conflict account of déjà vu and propose that this account of the experience may provide a coherent explanation as to why déjà vu experiences tend to decrease with age in the non-clinical population.

Accounting for the strangeness, infrequency, and suddenness of déjà vu

Barzykowski and Moulin argue that déjà vu is a natural product of autobiographical memory retrieval. Their proposal fails to account for three salient properties of déjà vu experiences: Their strangeness, their infrequency, and their characteristically sudden onset. Accounting for these properties is necessary for proper integration of déjà vu into autobiographical memory research.

Insights into déjà vu: Associations between the frequency of experience and amplitudes of low-frequency oscillations in resting-state functional magnetic resonance imaging

The phenomenon of déjà vu (DV) has intrigued scientists for decades, yet its neurophysiological underpinnings remain elusive. Brain regions have been identified in which morphometry differs between healthy individuals according to the frequency of their DV experiences. This study built upon these findings by assessing if and how neural activity in these and other brain regions also differ with respect to DV experience. Resting-state fMRI was performed on 68 healthy volunteers, 44 of whom reported DV experiences (DV group) and 24 who did not (NDV group). Using multivariate analyses, we then assessed the (fractional) amplitude of low-frequency fluctuations (fALFF/ALFF), a metric that is believed to index brain tissue excitability, for five discrete frequency bands within sets of brain regions implicated in DV and those comprising the default mode network (DMN). Analyses revealed significantly lower values of fALFF/ALFF for specific frequency bands in the DV relative to the NDV group, particularly within mesiotemporal structures, bilateral putamina, right caudatum, bilateral superior frontal cortices, left lateral parietal cortex, dorsal and ventral medial prefrontal cortex, and the posterior cingulate cortex. The pattern of differences in fALFF/ALFF measures between the brains of individuals who have experienced DV and those who have not provides new neurophysiological insights into this phenomenon, including the potential role of the DMN. We suggest that the erroneous feeling of familiarity arises from a temporary disruption of cortico-subcortical circuitry together with the upregulation of cortical excitability.

Subjective distinguishability of seizure and non-seizure Déjà Vu: A case report, brief literature review, and research prospects

Roughly two-thirds of all people report having experienced déjà vu-the odd feeling that a current experience is both novel and a repeat or replay of a previous, unrecalled experience. Reports of an association between déjà vu and seizure aura symptomatology have accumulated for over a century, and frequent déjà vu is also now known to be associated with focal seizures, particularly those of a medial temporal lobe (MTL) origin. A longstanding question is whether seizure-related déjà vu has the same basis and is the same subjective experience as non-seizure déjà vu. Survey research suggests that people who experience both seizure-related and non-seizure déjà vu can often subjectively distinguish between the two. We present a case of a person with a history of focal MTL seizures who reports having experienced both seizure-related and non-seizure common déjà vu, though the non-seizure type was more frequent during this person's youth than it is currently. The patient was studied with a virtual tour paradigm that has previously been shown to elicit déjà vu among non-clinical, young adult participants. The patient reported experiencing déjà vu of the common non-seizure type during the virtual tour paradigm, without associated abnormalities of the intracranial EEG. We situate this work in the context of broader ongoing projects examining the subjective correlates of seizures. The importance for memory research of virtual scenes, spatial tasks, virtual reality (VR), and this paradigm for isolating familiarity in the context of recall failure are discussed.

Déjà vu and prescience in a case of severe episodic amnesia following bilateral hippocampal lesions

Several studies pertaining to déjà vu have consistently made a connection with the perirhinal region, a region located below the hippocampus. This idea is strengthened by the fact that déjà vu is an erroneous sense of familiarity and that familiarity appears to largely depend on the perirhinal region in healthy subjects. In this context, the role of the hippocampus is particularly unclear as it is unknown whether or not it plays a role in the genesis of déjà vu. We report on the case of OHVR, an epileptic patient who suffers from severe episodic amnesia related to massive isolated bilateral damage to the hippocampus. In contrast, the perirhinal region is intact structurally and functionally. This patient reports frequent déjà vu but also another experiential phenomenon with a prominent feeling of prescience, which shows some of the characteristics of déjà vécu. She clearly distinguishes both. She also developed a form of synaesthesia by attributing affective valence to numbers. This study shows that déjà vu can occur in cases of amnesia with massively damaged hippocampi and confirms that the perirhinal region is a core region for déjà vu, using a different approach from previous reports. It also provides clues about a potential influence of hippocampal alterations in déjà vécu.

Functional activity changes in memory and emotional systems of healthy subjects with déjà vu

Déjà vu (DV) is a fascinating and mysterious human experience that has attracted interest from psychologists and neuroscientists for over a century. In recent years, several studies have been conducted to unravel the psychological and neurological correlates of this phenomenon. However, the neural mechanisms underlying the DV experience in benign manifestations are still poorly understood. Thirty-three healthy volunteers completed an extensive neuropsychiatric and neuropsychological battery including personality evaluation. The presence of DV was assessed with the Inventory for Deja vu Experiences Assessment. Participants underwent episodic memory learning test, and 2 days later during event-related functional magnetic resonance imaging (fMRI), they are asked to rate old and new pictures as a novel, moderately/very familiar, or recollected. We identified 18 subjects with DV (DV+) and 15 without DV (DV-) matched for demographical, neuropsychological, and personality characteristics. At a behavioral level, no significant difference was detected in the episodic memory tasks between DV+ and DV-. Functional magnetic resonance imaging analysis revealed that DV+, independently from task conditions, were characterized by increased activity of the bilateral insula coupled with reduced activation in the right parahippocampal, both hippocampi, superior/middle temporal gyri, thalami, caudate nuclei, and superior frontal gyri with respect to DV-. Our study demonstrates that individuals who experienced DV are not characterized by different performance underlying familiarity/recollection memory processes. However, fMRI results provide evidence that the physiological DV experience is associated with the employment of different neural responses of brain regions involved in memory and emotional processes.

Déjà vu experiences in anxiety

Déjà vu occurs when a novel event is experienced with an erroneous sense of familiarity. Memory researchers theorise that this arises due to an error in the processes underlying the recognition memory system. Research has indicated that there may be a link between high levels of anxiety and increased frequency and intensity of déjà vu, however, there has been a comparatively little characterisation of déjà vu as experienced by individuals with clinical anxiety. We used an online questionnaire to collect data from individuals self-reporting a clinical diagnosis of anxiety, as well as from age-matched controls. The Anxiety Group reported a significantly higher frequency of déjà vu episodes over the previous month than controls. They also reported experiencing déjà vu more frequently and with higher intensity during periods of high anxiety. In addition, the Anxiety Group reported finding déjà vu episodes significantly more distressing than the Control Group. The findings indicate that there are differences in déjà vu experienced by people reporting high levels of anxiety compared to healthy controls without an anxiety diagnosis. We discuss structural and neural mechanisms thought to underpin déjà vu in relation to these results.

fMRI evidence supporting the role of memory conflict in the déjà vu experience

Attempts to generate déjà vu experimentally have largely focused on engineering partial familiarity for stimuli, relying on an ensuing, but unprompted evaluation of conflict to generate the experience. Without verification that experimentally-generated familiarity is accompanied by the awareness of stimulus novelty, these experimental procedures potentially provide an incomplete déjà vu analogue. We used a modified version of the Deese-Roediger-McDermott (DRM) false memory procedure to generate both familiarity and novelty within a déjà vu analogue - we coupled experimentally-generated familiarity with cues indicating that the familiarity was erroneous, using this additional source of mnemonic information to generate cognitive conflict in our participants. We collected fMRI and behavioural data from 21 participants, 16 of whom reported déjà vu. Using univariate contrasts we identified brain regions associated with mnemonic conflict, including the anterior cingulate cortex, medial prefrontal cortex and parietal cortex. This is the first experiment to image an analogue of the déjà vu experience in healthy volunteers. The increased likelihood of déjà vu reports to DRM critical lures correctly identified as "new", and the activation of neural substrates supporting the experience of cognitive conflict during déjà vu, suggest that the resolution of memory conflict may play an integral role in déjà vu.

Insight into epileptic and physiological déjà vu: from a multicentric cohort study

BACKGROUND AND PURPOSE

The presence of a continuum between physiological déjà vu (DV) and epileptic DV is still not known as well as epidemiological data in the Italian population. The aim was to identify the epidemiological distribution of DV in Italy, and secondly to look for specific features of DV able to discriminate between epileptic and non-epileptic DV.

METHODS

In all, 1000 individuals, 543 healthy controls (C) (313 women; age 40 ± 15 years) and 457 patients with epilepsy (E) (260 women; age 39 ± 14 years), were prospectively recruited from 10 outpatient neurological clinics throughout Italy. All populations were screened using the Italian Inventory for Déjà Vu Experiences Assessment (I-IDEA) test and E and pairwise C underwent a comprehensive epilepsy interview.

RESULTS

Of E, 69% stated that they experienced 'recognition' and 13.2% reported that this feeling occurred from a few times a month to at least weekly (versus 7.7% of the control group). Furthermore, a greater percentage of E (6.8% vs. 2.2%) reported that from a few times a month to at least weekly they felt that it seemed as though everything around was not real. In E, the feeling of recognition raised fright (22.3% vs. 13.2%) and a sense of oppression (19.4% vs. 9.4%). A fifth of E felt recognition during epileptic seizures.

CONCLUSION

Only E regardless of aetiology firmly answered that they had the feeling of recognition during an epileptic seizure; thus question 14 of the I-IDEA test part 2 discriminated E from C. Paranormal activity, remembering dreams and travel frequency were mostly correlated to DV in E suggesting that the visual-memory network might be involved in epileptic DV.

Overcoming familiarity illusions in a single case with persistent déjà vu

While occasional déjà vu is benign in the general population, rare neuropsychological cases with persistent déjà vu have been described in the literature. We report the case of MN, a 25-year-old woman, who suffered a cerebral haemorrhage in the right thalamo-callosal region and experienced recurrent déjà vu episodes. Through clinical interviews and memory tasks related to déjà vu, we assumed that source memory errors and an inappropriate feeling of familiarity (measured by the number of false recognitions) were critically involved in MN's déjà vu. Based on this, we developed the first neuropsychological intervention dedicated to déjà vu. The rationale was to train MN to detect elements that could produce an inappropriate feeling of familiarity and to promote metacognitive awareness about déjà vu. This intervention was effective at reducing the frequency of déjà vu episodes in MN's daily life, as well as the number of false recognitions in memory tasks. In addition to its clinical contribution, this single-case study contributes to the limited literature on patients whose déjà vu is not related to epileptic abnormalities and medial temporal brain damage, and provide supportive evidence of the role of an erroneous feeling of familiarity and of metacognitive processes in déjà vu.

Hippocampal involvement in nonpathological déjà vu: Subfield vulnerability rather than temporal lobe epilepsy equivalent

INTRODUCTION

Morphological correlates of nonpathological déjà vu (DV) have been identified recently within the human brain. Significantly reduced gray matter volume (GMV) within a set of cortical and subcortical regions reported in subjects experiencing DV seems to mirror the distribution of GMV reduction in mesial temporal lobe epilepsy (MTLE) patients but vary in terms of the hippocampus. Another condition associated with hippocampal GMV reduction and DV alike disturbance in memory processing is schizophrenia (SCH). Here, we tested the hypothesis that hippocampal involvement in nonpathological DV resembles more closely the pattern of GMV decrease observed in MTLE compared with that occurring in SCH.

METHODS

Using automated segmentation of the MRI data we compared the medians of GMV within 12 specific hippocampal subfields in healthy individuals that do (DV+; N = 87) and do not report déjà vu experience (DV-; N = 26), and patients with MTLE (N = 47) and SCH (N = 29). By Pearson correlation, we then evaluated the similarity of MTLE and SCH groups to DV+ group with respect to spatial distribution of GMV deviation from DV- group.

RESULTS

Significant GMV decrease was found in MTLE group in most of the subfields. There were just trends in the hippocampal GMV decrease found in DV+ or SCH groups. Concerning the spatial distribution of GMV decrease, we revealed statistically significant correlation for the left hippocampus for SCH vs DV+. Otherwise there was no statistically significant correlation.

CONCLUSIONS

Our findings reveal structural features of hippocampal involvement in nonpathological DV, MTLE, and SCH. Despite our expectations, the pattern of GMV reduction in the DV+ relative to the DV- group does not resemble the pattern observed in MTLE any more than that observed in SCH. The highly similar patterns of the three clinical groups rather suggest an increased vulnerability of certain hippocampal subfields; namely, Cornu Ammonis (CA)4, CA3, dentate gyrus granular cell layer (GC-DG), hippocampal-amygdaloid transition area (HATA) and subiculum.

Abnormal rsFC and GMV changes in parahippocampal and DLPFC for high Déjà vu experienced subjects

How déjà vu works has long been a mystery, partially because of its characteristics of unpredictable occurrences and quick disappearances, which make it difficult to be explored. Previous studies have described the anatomical structures underlying déjà vu in healthy subjects; however, the functional mechanism of déjà vu remains unclear. Therefore, this study investigated the brain structural and functional components underlying déjà vu by combining voxel-based morphometry analysis (VBM) with resting-state functional connectivity (rsFC). The VBM analysis revealed that the anterior parahippocampal gyrus (PHG) had significantly less grey matter volume (GMV) in high déjà vu group than low group, confirming previous studies. Further functional connectivity analysis revealed that the frequency of déjà vu experiences was negatively correlated with the strength of the rsFC between anterior dorsal lateral prefrontal cortex (DLPFC) and anterior PHG but positively correlated with the strength of the rsFC between posterior DLPFC and posterior PHG. Moreover, the frequency of déjà vu experiences was negatively correlated with the strength of the rsFC between the anterior and posterior regions of the PHG. These findings indicated that familiarity without recollection (PHG) and superior context monitoring (DLPFC) are critical for real-life déjà vu experiences.

Validation Study of Italian Version of Inventory for Déjà Vu Experiences Assessment (I-IDEA): A Screening Tool to Detect Déjà Vu Phenomenon in Italian Healthy Individuals

The Inventory Déjà Vu Experiences Assessment (IDEA) is the only screening instrument proposed to evaluate the Déjà vu (DV) experience. Here, we intended to validate the Italian version of IDEA (I-IDEA) and at the same time to investigate the incidence and subjective qualities of the DV phenomenon in healthy Italian adult individuals on basis of an Italian multicentre observational study. In this study, we report normative data on the I-IDEA, collected on a sample of 542 Italian healthy subjects aging between 18-70 years (average age: 40) with a formal educational from 1-19 years. From September 2013 to March 2016, we recruited 542 healthy volunteers from 10 outpatient neurological clinics in Italy. All participants (i.e., family members of neurological patients enrolled, medical students, physicians) had no neurological or psychiatric illness and gave their informed consent to participate in the study. All subjects enrolled self-administered the questionnaire and they were able to complete I-IDEA test without any support. In total, 396 (73%) of the 542 healthy controls experienced the DV phenomenon. The frequency of DV was inversely related to age as well as to derealisation, jamais vu, precognitive dreams, depersonalization, paranormal activity, remembering dreams, travel frequency, and daydreams (all p < 0.012). The Italian version of IDEA maintains good properties, thus confirming that this instrument is reliable for detecting and characterising the DV phenomenon.

Déjà Vu Experiences in Healthy Czech Adults

The study examines the prevalence of déjà vu in healthy Czech adults and explores its relationships with a number of variables: age, sex, neuroticism, depression, the degree of irritability in the limbic system, perceived stress, and finally attachment avoidance and anxiety. The participants were 365 healthy adults ranging from 18 to 70 years recruited in the Czech Republic (mean age = 29.05; SD = 11.17) who filled out online questionnaires. Déjà vu experiences were reported by 324 (88.8%) of them. Persons who experienced déjà vu were younger than the persons who had not experienced it. We found that sex, levels of neuroticism, depression, perceived stress, and attachment did not serve as predictors of experiences of déjà vu phenomena. Finally, those who had reported déjà vu experiences reported more limbic system irritability symptoms. We discuss the possibility that déjà vu reports together with other studied variables mainly reflect the participants' willingness to report "extraordinal" experiences.

History repeating itself: Arnaud's case of pathological déjà vu

We present a translation of Arnaud's (1896) case report of Patient Louis, a case he describes as having a pathological form of déjà vu. Louis has the delusional belief that the present moment is a repetition of an exact same previous event. Arnaud's paper is critical for two reasons. Firstly, it is amongst the first articles in the scientific literature to describe the déjà vu experience using the term 'déjà vu'. Secondly, the case report of someone with delusional and persistent déjà vu, anticipates recently reported cases with similar symptoms, which are beginning to gain interest as a particular form of memory disorder. We offer a contemporary analysis of Louis and conclude that, whilst the article was critical in the development of déjà vu as a scientific concern, Louis's distorted memory is not best described as déjà vu, but rather as a form of reduplicative paramnesia described as recollective confabulation.

Is there anything distinctive about epileptic deja vu?

BACKGROUND

Déjà vu can occur as an aura of temporal lobe epilepsy and in some psychiatric conditions but is also common in the general population. It is unclear whether any clinical features distinguish pathological and physiological forms of déjà vu.

METHODS

50 epileptic patients with ictal déjà vu, 50 non-epileptic patients attending general neurology clinics and 50 medical students at Edinburgh University were recruited. Data were collected on demographic factors, the experience of déjà vu using a questionnaire based on Sno's Inventory for Déjà Vu Experiences Assessment, symptoms of anxiety and depression using the Hospital Anxiety and Depression Scale as well as seizure characteristics, anti-epileptic medications, handedness, EEG and neuroimaging findings for epileptic patients.

RESULTS

73.5% of neurology patients, 88% of students and (by definition) all epilepsy patients had experienced déjà vu. The experience of déjà vu itself was similar in the three groups. Epileptic déjà vu occurred more frequently and lasted somewhat longer than physiological déjà vu. Epilepsy patients were more likely to report prior fatigue and concentrated activity, associated derealisation, olfactory and gustatory hallucinations, physical symptoms such as headaches, abdominal sensations and fear. After controlling for study group, anxiety and depression scores were not associated with déjà vu frequency.

CONCLUSIONS

Déjà vu is common and qualitatively similar whether it occurs as an epileptic aura or normal phenomenon. However ictal déjà vu occurs more frequently and is accompanied by several distinctive features. It is distinguished primarily by 'the company it keeps'.

Déjà vu experiences in healthy subjects are unrelated to laboratory tests of recollection and familiarity for word stimuli

Recent neuropsychological and neuroscientific research suggests that people who experience more déjà vu display characteristic patterns in normal recognition memory. We conducted a large individual differences study (n = 206) to test these predictions using recollection and familiarity parameters recovered from a standard memory task. Participants reported déjà vu frequency and a number of its correlates, and completed a recognition memory task analogous to a Remember-Know procedure. The individual difference measures replicated an established correlation between déjà vu frequency and frequency of travel, and recognition performance showed well-established word frequency and accuracy effects. Contrary to predictions, no relationships were found between déjà vu frequency and recollection or familiarity memory parameters from the recognition test. We suggest that déjà vu in the healthy population reflects a mismatch between errant memory signaling and memory monitoring processes not easily characterized by standard recognition memory task performance.

Epilepsy, behavior, and art (Epilepsy, Brain, and Mind, part 1)

Epilepsy is both a disease of the brain and the mind. Brain diseases, structural and/or functional, underlie the appearance of epilepsy, but the notion of epilepsy is larger and cannot be reduced exclusively to the brain. We can therefore look at epilepsy from two angles. The first perspective is intrinsic: the etiology and pathophysiology, problems of therapy, impact on the brain networks, and the "mind" aspects of brain functions - cognitive, emotional, and affective. The second perspective is extrinsic: the social interactions of the person with epilepsy, the influence of the surrounding environment, and the influences of epilepsy on society. All these aspects reaching far beyond the pure biological nature of epilepsy have been the topics of two International Congresses of Epilepsy, Brain, and Mind that were held in Prague, Czech Republic, in 2010 and 2012 (the third Congress will be held in Brno, Czech Republic on April 3-5, 2014; www.epilepsy-brain-mind2014.eu). Here, we present the first of two papers with extended summaries of selected presentations of the 2012 Congress that focused on epilepsy, behavior, and art.

Underestimated phenomena: higher cortical dysfunctions during migraine aura

INTRODUCTION

Aura occurs in 20-30% of patients with migraine. Some descriptions of aura go far beyond the most frequent visual and sensory symptoms, suggesting the involvement of different cortical areas. The aim of this prospective study was to evaluate the frequency and types of disorders of higher cortical functions (HCF) that occur during visual and/or sensory aura.

METHODS

We interviewed 60 patients with visual and/or sensory aura about HCF disorders of praxia, gnosia, memory, and speech, during aura. Patients were divided into two groups, with and without HCF disorders, and were compared in terms of demographic data and aura characteristics.

RESULTS

From all 60 patients, 65% reported at least one HCF disorder during aura. The patients with HCF disorders had longer-lasting auras (28.51 ± 16.39 vs. 19.76 ± 11.23, P  = 0.016). The most common HCF disorders were motor dysphasia (82.05%) and dysnomia (30.74%). Motor dysphasia was more often reported by patients with visual as well as sensory aura ( P  = 0.002). The number of HCF disorders correlated with the aura duration ( P  = 0.003).

CONCLUSION

According to our results, HCF disorders during aura occur more often than previously thought. The aura duration has some influence on the HCF disorders.

Déjà vu phenomenon-related EEG pattern. Case report

Background

Déjà vu (DV, from French déjà vu — “already seen”) is an aberration of psychic activity associated with transitory erroneous perception of novel circumstances, objects, or people as already known.

Objective

This study aimed to record the EEG pattern of déjà vu.

Methods

The subjects participated in a survey concerning déjà vu characteristics and underwent ambulatory EEG monitoring (12–16 h).

Results

In patients with epilepsy, DV episodes began with polyspike activity in the right temporal lobe region and, in some cases, ended with slow-wave theta–delta activity over the right hemisphere. There were no epileptic discharges in healthy respondents during DV.

Conclusion

Two types of déjà vu are suggested to exist: “pathological-epileptic” déjà vu, characteristic of patients with epilepsy and equivalent to an epileptic seizure, and “nonpathological-nonepileptic” déjà vu, which is characteristic of healthy people and psychological phenomenon.