Involuntary memory signals in the medial temporal lobe.

We highlight recent progress in neuroimaging and neuropsychological research on memory mechanisms in the medial temporal lobe that speaks to the involuntary nature of memory retrieval processes. We suggest that evidence form these studies supports Barzykowski and Moulin's proposal that memory signals involved in experiences of familiarity and déjà vu can be generated in the absence of retrieval intentionality.

Are involuntary autobiographical memory and déjà vu cognitive failures?

This commentary supports Barzykowski and Moulin's model, but departs from it on the question of functionality, where IAMs and déjà vu fractionate. The authors seem to say that IAMs are functional, while déjà vu is not. As there is no hard evidence supporting the idea that IAMs are functional, I argue that both phenomena should be viewed as cognitive failures.

The misidentification syndromes and source memory deficits with their neuroanatomical correlates from neuropsychological perspective.

The suggested model is discussed with reference to two clinical populations with memory disorders - patients with misidentification syndromes and those with source memory impairment, both of whom may present with (broadly conceived) déjà vu phenomenon, without insight into false feeling of familiarity. The role of the anterior thalamic nucleus and retrosplenial cortex for autobiographical memory and familiarity is highlighted.

The relation of subjective experience to cognitive processing.

Barzykowski and Moulin argue that common memory processes form the basis of involuntary autobiographical memory and the déjà vu experience. We think that they underemphasize the potential dissociability between processes that enact retrieval and the processes that produce conscious experience. We propose that retrieval and conscious experience result from different processes in both involuntary autobiographical memory and déjà vu experiences.

Association of Deja vu With Cardiovascular Diseases.

Recent studies have suggested a link between déjà vu and cardiovascular diseases (CVDs). While the mechanism for this association is not fully understood, 1 theory suggests that déjà vu may be a result of a disruption in the temporal lobe, which is also responsible for regulating blood pressure and heart rate. Another theory suggests that there may be a shared genetic factor between the 2 conditions, with certain individuals being predisposed to experiencing both. The Apolipoprotein E (APOE) gene, in particular, has been associated with memory processing, Alzheimer's disease, and an increased risk of CVD. The protein encoded by this gene is involved in the metabolism of lipoproteins, including cholesterol and triglycerides, and is also involved in the development of atherosclerosis, which is a key risk factor for CVD. Several hypotheses have been proposed to explain how the APOE4 isoform contributes to CVD, including impairing the clearance of lipoproteins, promoting inflammation, and causing endothelial dysfunction. Psychological factors such as stress may also contribute to the development of CVD, and déjà vu may be associated with emotional arousal and stress. Further research is needed to fully understand the link between déjà vu and CVDs and to explore potential treatment options for individuals who experience both conditions.

A postdictive bias associated with déjà vu.

Recent research links reports of déjà vu - the feeling of having experienced something before despite knowing otherwise - with an illusory feeling of prediction. In the present study, a new finding is presented in which reports of déjà vu are associated not only with a predictive bias, but also with a postdictive bias, whereby people are more likely to feel that an event unfolded as expected after the event prompted déjà vu than after it did not. During a virtual tour, feelings of predicting the next turn were more likely during reported déjà vu, as in prior research. Then, after actually seeing the turn, participants exhibited a postdictive bias toward feeling that the scene unfolded as expected following déjà vu reports. This postdictive bias following déjà vu reports was associated with higher perceived scene familiarity intensity. A potential reason for this association may be that high familiarity intensity as an event outcome unfolds falsely signals confirmatory evidence of having sensed all along how it would unfold. Future research should further investigate this possibility.

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.

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.

Many Faces of Déjà Vu: a Narrative Review.

French expression standing for the phrase "already seen" is a déjà vu. It is thought that as much as 97% of the population have experienced déjà vu at least once in their lifetime and 67% experience it regularly. The explanations of this phenomenon in novels and poems include reincarnation, dreams, organic factors, and unconscious memories. In this narrative review connection between déjà vu and various other conditions has been mentioned: false memories, temporal lobe epilepsy and other neurological conditions. In psychiatric patients déjà vu phenomenon is more often seen in patients with anxiety and people with derealisation/ depersonalization. It seems that temporal region is the origin of déjà vu phenomena in both healthy individuals and in individuals with neurological and psychiatric conditions, but the exact mechanism of this phenomenon is however still unknown. More attention should also be given to déjà vu from philosophical and religious perspectives as well. Déjà vu is still an enigma which could only be revealed with multidisciplinary approach through cooperation between neurologists, brain scientists, psychiatrists and experimental psychologists.

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.

A case of epilepsy induced by eating or by visual stimuli of food made of minced meat.

We report a 34-year-old woman with eating epilepsy induced not only by eating but also seeing foods made of minced meat. In her early 20s of age, she started having simple partial seizures (SPS) as flashback and epigastric discomfort induced by particular foods. When she was 33 years old, she developed SPS, followed by secondarily generalized tonic-clonic seizure (sGTCS) provoked by eating a hot dog, and 6 months later, only seeing the video of dumpling. We performed video electroencephalogram (EEG) monitoring while she was seeing the video of soup dumpling, which most likely caused sGTCS. Ictal EEG showed rhythmic theta activity in the left frontal to mid-temporal area, followed by generalized seizure pattern. In this patient, seizures were provoked not only by eating particular foods but also by seeing these. This suggests a form of epilepsy involving visual stimuli.

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.

Abnormal Time Experiences in Major Depression: An Empirical Qualitative Study.

BACKGROUND: Phenomenological psychopathology, through theoretical and idiographic studies, conceptualizes major depressive disorder (MDD) as a disorder of time experience. Investigations on abnormal time experience (ATE) in MDD adopting methodologies requested by the standards of empirical sciences are still lacking. Our study aimed to provide a qualitative analysis, on an empirical ground and on a large scale, of narratives of temporal experiences of persons affected by MDD. METHODS: We interviewed 550 consecutive patients affected by affective and schizophrenic disorders. Clinical files were analysed by means of consensual qualitative research. RESULTS: Out of 100 MDD patients, 96 reported at least 1 ATE. The principal categories of ATE are vital retardation - the experience of a stagnation of endogenous vital processes (37 patients), the experience of present and future dominated by the past (29 patients), and the experience of the slackening of the flow oftime (25 patients). A comparison with ATE in schizophrenia patients showed that in MDD, unlike in schizophrenia, there is no disarticulation of time experience (disorder of temporal synthesis) but rather a disorder of conation or inhibition of becoming. LIMITATIONS: The interview style was not meant to make a quantitative assessment ("false negatives" cannot be excluded). CONCLUSIONS: Our findings confirm the relevance of distinctive features of ATE in MDD, support the hypothesis of an intrinsic disordered temporal structure in depressive symptoms, and may have direct implications in clinical practice, especially in relation to differential diagnosis, setting the boundaries between "true" and milder forms of depression, and neurobiological research.

Déjà vecu for news events but not personal events: A dissociation between autobiographical and non-autobiographical episodic memory processing.

In déjà vu, the feeling that what we are currently experiencing we have experienced before is fleeting and is not accepted as true. In contrast, in déjà vecu or "recollective confabulation", the sense of déjà vu is persistent and convincing, and patients genuinely believe that they have lived through the current moment at some previous time. In previous reports of cases of déjà vecu, both personal events and non-personal, world events gave rise to this experience. In this paper we describe a patient whose déjà vecu experiences are entirely restricted to non-personal events, suggesting that autobiographical and non-autobiographical episodic memory processing can dissociate. We suggest that this dissociation is secondary to differences in the degree to which personal and emotional associations are formed for these two different types of event, and offer a two-factor theory of déjà vecu.

Ictal fear: Associations with age, gender, and other experiential phenomena.

PURPOSE: The aim of this study was to determine the relationship of fear to other auras and to gender and age using a large database. METHODS: The Epilepsy Phenome/Genome Project (EPGP) is a multicenter, multicontinental cross-sectional study in which ictal symptomatology and other data were ascertained in a standardized series of questionnaires then corroborated by epilepsy specialists. Auras were classified into subgroups of symptoms, with ictal fear, panic, or anxiety as a single category. RESULTS: Of 536 participants with focal epilepsy, 72 were coded as having ictal fear/panic/anxiety. Reviewing raw patient responses, 12 participants were deemed not to have fear, and 24 had inadequate data, leaving 36 (7%) of 512 with definite ictal fear. In univariate analyses, fear was significantly associated with auras historically considered temporal lobe in origin, including cephalic, olfactory, and visceral complaints; déjà vu; and derealization. On both univariate and multivariate stepwise analyses, fear was associated with jamais vu and auras with cardiac symptoms, dyspnea, and chest tightening. Expressive aphasia was associated with fear on univariate analysis only, but the general category of aphasias was associated with fear only in the multivariate model. There was no age or gender relationship with fear when compared to the overall population with focal epilepsy that was studied under the EPGP. Patients with ictal fear were more likely to have a right hemisphere seizure focus. CONCLUSIONS: Ictal fear was strongly associated with other auras considered to originate from the limbic system. No relationship of fear with age or gender was observed.

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.

Psychopathology of Lived Time: Abnormal Time Experience in Persons With Schizophrenia.

Abnormal time experience (ATE) in schizophrenia is a long-standing theme of phenomenological psychopathology. This is because temporality constitutes the bedrock of any experience and its integrity is fundamental for the sense of coherence and continuity of selfhood and personal identity. To characterize ATE in schizophrenia patients as compared to major depressives we interviewed, in a clinical setting over a period of 15 years, 550 consecutive patients affected by schizophrenic and affective disorders. Clinical files were analyzed by means of Consensual Qualitative Research (CQR), an inductive method suited to research that requires rich descriptions of inner experiences. Of the whole sample, 109 persons affected by schizophrenic (n = 95 acute, n = 14 chronic) and 37 by major depression reported at least 1 ATE. ATE are more represented in acute (N = 109 out of 198; 55%) than in chronic schizophrenic patients (N = 14 out of 103; 13%). The main feature of ATE in people with schizophrenia is the fragmentation of time experience (71 out of 109 patients), an impairment of the automatic and prereflexive synthesis of primal impression-retention-protention. This includes 4 subcategories: disruption of time flowing, déjà vu/vecu, premonitions about oneself and the external world. We contrasted ATE in schizophrenia and in major depression, finding relevant differences: in major depressives there is no disarticulation of time experience, rather timelessness because time lacks duration, not articulation. These core features of the schizophrenic pheno-phenotype may be related to self-disorders and to the manifold of characteristic schizophrenic symptoms, including so called bizarre delusions and verbal-acoustic hallucinations.