Interictal 18FDG PET findings in temporal lobe epilepsy with déjà vu

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.

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.

Electrical engram: how deep brain stimulation affects memory

Deep brain stimulation (DBS) is a surgical procedure involving implantation of a pacemaker that sends electric impulses to specific brain regions. DBS has been applied in patients with Parkinson's disease, depression, and obsessive-compulsive disorder (among others), and more recently in patients with Alzheimer's disease to improve memory functions. Current DBS approaches are based on the concept that high-frequency stimulation inhibits or excites specific brain regions. However, because DBS entails the application of repetitive electrical stimuli, it primarily exerts an effect on extracellular field-potential oscillations similar to those recorded with electroencephalography. Here, we suggest a new perspective on how DBS may ameliorate memory dysfunction: it may enhance normal electrophysiological patterns underlying long-term memory processes within the medial temporal lobe.

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.

Déjà experiences in temporal lobe epilepsy

Historically, déjà vu has been linked to seizure activity in temporal lobe epilepsy, and clinical reports suggest that many patients experience the phenomenon as a manifestation of simple partial seizures. We review studies on déjà vu in epilepsy with reference to recent advances in the understanding of déjà vu from a cognitive and neuropsychological standpoint. We propose a decoupled familiarity hypothesis, whereby déjà vu is produced by an erroneous feeling of familiarity which is not in keeping with current cognitive processing. Our hypothesis converges on a parahippocampal dysfunction as the locus of déjà vu experiences. However, several other temporal lobe structures feature in reports of déjà vu in epilepsy. We suggest that some of the inconsistency in the literature derives from a poor classification of the various types of déjà experiences. We propose déjà vu/déjà vécu as one way of understanding déjà experiences more fully. This distinction is based on current models of memory function, where déjà vu is caused by erroneous familiarity and déjà vécu by erroneous recollection. Priorities for future research and clinical issues are discussed.

Two forms of déjà vu experiences in patients with epilepsy

Persons with epilepsy experience déjà vu phenomena with or without seizure recognition. Déjà vu experiences are also common mental phenomena in nonclinical individuals. The purpose of this study was to clarify two forms of déjà vu experiences in persons with epilepsy. Déjà vu experiences of 312 patients with epilepsy and 402 nonclinical individuals were evaluated using the Inventory of Déjà vu Experiences Assessment. In the patients with epilepsy, characteristics of déjà vu experiences with seizure recognition (SR form) were compared with those experiences with no seizure recognition (NSR form). The incidence (63.1%) of déjà vu experiences in patients with epilepsy was significantly lower than that (76.1%) of nonclinical individuals (chi(2)=14.2, P=0.000). Among the patients with epilepsy, 55.6% had the NSR form and 24.0% had the SR form. Those with the NSR form manifested fewer psychopathological characteristics than did those with the SR form. Patients tended to view the SR form more negatively (i.e., frightened, uncomfortable, or disturbed) than the NSR form. The NSR form was significantly associated with idiopathic generalized epilepsies, less frequent antiepileptic drug administration, and no mesial temporal sclerosis. Although there was a significant association between the frequency of the SR form and patients' habitual seizures, the frequency of the NSR form was not associated with the frequency of the patients' habitual seizures. Persons with epilepsy experience two forms of déjà vu which are differently associated with their seizure recognition.

Déjà-vu in temporal lobe epilepsy: metabolic pattern of cortical involvement in patients with normal brain MRI

To contribute to the identification of brain regions involved in déjà-vu, we studied the metabolic pattern of cortical involvement in patients with seizures of temporal lobe origin presenting with or without déjà-vu. Using voxel-based analysis of 18FDG-PET brain scans, we compared glucose metabolic rate of 8 patients with déjà-vu, 8 patients without déjà-vu, and 20 age-matched healthy subjects. Patients were selected after comprehensive non-invasive presurgical evaluation, including normal brain MRI and surface electroclinical features compatible with unilateral temporal lobe epilepsy (TLE). Patients with and without déjà-vu did not differ in terms of age, gender, epilepsy lateralization, epilepsy onset, epilepsy duration, and other subjective ictal manifestations. TLE patients with déjà-vu exhibited ipsilateral hypometabolism of superior temporal gyrus and of parahippocampal region, in the vicinity of perirhinal/entorhinal cortex, in comparison either to healthy subjects or to TLE patients without déjà-vu (p<0.05 FDR-corrected). By contrast, no difference was found between patient subgroups for hypometabolism of hippocampus and amygdala. At an individual-level, in comparison to healthy subjects, hypometabolism of both parahippocampal region and superior temporal gyrus was present in 7/8 patients with déjà-vu. Hippocampal metabolism was spared in 3 of these 7 patients. These findings argue for metabolic dysfunction of a medial-lateral temporal network in patients with déjà-vu and normal brain MRI. Within the medial temporal lobe, specific involvement of the parahippocampal region, often in the absence of hippocampal impairment, suggests that the feeling of familiarity during seizures greatly depends on alteration of the recognition memory system.

Normal patterns of déjà experience in a healthy, blind male: Challenging optical pathway delay theory

We report the case of a 25-year-old healthy, blind male, MT, who experiences normal patterns of déjà vu. The optical pathway delay theory of déjà vu formation assumes that neuronal input from the optical pathways is necessary for the formation of the experience. Surprisingly, although the sensation of déjà vu is known to be experienced by blind individuals, we believe this to be the first reported application of this knowledge to the understanding of the phenomenon. Visual input is not present in MT, yet the experiences he describes are consistent with reports in the literature of déjà vu occurrence in sighted people. The fact that blind people can experience déjà vu challenges the optical pathway delay theory, and alternative causes are briefly discussed.

Did Fyodor Mikhailovich Dostoevsky suffer from mesial temporal lobe epilepsy?

Many scientific authors--among them famous names such as Henri Gastaut or Sigmund Freud--dealt with the question from what kind of epilepsy Fyodor Mikhailovitch Dostoevsky (1821-1881) might had suffered. Because of the tight interplay between Dostoevsky's literary work and his own disease we throw light on the author's epilepsy against the background of his epileptic fictional characters. Moreover, we attempt to classify Dostoevsky's epilepsy on the basis of his bibliography, language, and literary work.

D�j� vu in neurology

The significance of deja vu is widely recognised in the context of temporal lobe epilepsy, and enquiry about deja vu is frequently made in the clinical assessment of patients with possible epilepsy. Deja vu has also been associated with several psychiatric disorders. The historical context of current understanding of deja vu is discussed. The literature reveals deja vu to be a common phenomenon consistent with normality. Several authors have suggested the existence of a "pathological" form of deja vu that differs, qualitatively or quantitatively, from "non-pathological" deja vu. The features of deja vu suggesting neurological or psychiatric pathology are discussed. Several neuroanatomical and psychological models of the deja vu experience are highlighted, implicating the perceptual, mnemonic and affective regions of the lateral temporal cortex, hippocampus and amygdala in the genesis of deja vu. A possible genetic basis for a neurochemical model of deja vu is discussed. Clinical approaches to the patient presenting with possible deja vu are proposed.

Exacerbation of mania secondary to right temporal lobe astrocytoma in a bipolar patient previously stabilized on valproate

OBJECTIVES

To investigate breakthrough mania secondary to a right temporal lobe neoplasm in a bipolar patient previously stabilized on sodium divalproex.

BACKGROUND

Right hemispheric brain tumors involving the orbitofrontal or basotemporal cortex are a rare cause of secondary mania. In such cases, early neurologic signs may be difficult to distinguish from bipolar symptoms. Breakthrough mania secondary to brain neoplasm in a bipolar patient stabilized on medication is an extremely rare phenomena which has not been previously reported.

METHOD

The clinical course of a bipolar subject stabilized on valproate who developed mania secondary to a right temporal lobe astrocytoma is described. Serial brain magnetic resonance imaging (MRI), baseline electroencephalogram (EEG), and neuropsychiatric evaluations were used to examine the relationship between the patient's brain mass and behavioral disturbances.

RESULTS

Symptoms were those that accompanied prior episodes of mania. In addition, signs of temporal lobe dysfunction were evident including periods of detachment, déjà vu experiences, and olfactory hallucinations. In the context of mania, depersonalization was initially attributed to bipolar symptoms. Only several months later, when olfactory hallucinations and alterations in consciousness became evident, was a temporal lobe lesion suspected. Neuropsychiatric abnormalities responded to a combination of surgical intervention, radiation therapy, and topiramate, however the tumor was advanced and invasive at diagnosis resulting in a poor prognosis.

CONCLUSIONS

This case suggests that clinicians examining unexplained cases of breakthrough mania should be vigilant for early signs of temporal lobe dysfunction, which could aid in detecting treatable lesions.

Re-examination of the value of localising aura sensations and lateralising interictal epileptiform discharges in view of structural lesions demonstrated by MRI

We examined the relationship between MRI lesions and electro-clinical findings with special attention to the localising value of aura sensations and the sides of interictal epileptiform discharges in 327 patients with symptomatic localisation-related epilepsy. As a result, while autonomic as well as psychic auras were correlated with temporal lesions, simple motor seizures were associated with extra-temporal ones. Within the group of patients with temporal lobe epilepsy, autonomic but not psychic auras concurred significantly more often with medial temporal structural lesions. Furthermore, there was a significant difference between concordance rates between sides of MRI lesions and EEG foci as a function of laterality: while the right-sided MRI lesions constantly showed ipsilateral EEG foci, EEG foci concurring with the left-sided MRI lesions proved to be often falsely lateralising. From these results, we assumed that lateral as well as medial temporal involvement is needed in the genesis of the psychic aura in contrast to the autonomic aura, which could be induced without lateral temporal involvement, and lesions in the left hemisphere are more apt to induce secondarily epileptogenic than those in the right hemisphere.

A review of the déjà vu experience

For more than a century, the déjà vu experience has been examined through retrospective surveys, prospective surveys, and case studies. About 60% of the population has experienced déjà vu, and its frequency decreases with age. Déjà vu appears to be associated with stress and fatigue, and it shows a positive relationship with socioeconomic level and education. Scientific explanations of déjà vu fall into 4 categories: dual processing (2 cognitive processes momentarily out of synchrony), neurological (seizure, disruption in neuronal transmission), memory (implicit familiarity of unrecognized stimuli),and attentional (unattended perception followed by attended perception). Systematic research is needed on the prevalence and etiology of this culturally familiar cognitive experience, and several laboratory models may help clarify this illusion of recognition.

Demographic and psychological features of déjà vu experiences in a nonclinical Japanese population

The authors investigated the frequency and correlates of déjà vu experiences in 386 healthy adult volunteers recruited from several areas in Japan. Déjà vu experiences and related experiences were evaluated using the Inventory of Déjà vu Experiences Assessment. Déjà vu experiences were observed by 294 (76.2%) of the 386 participants. Persons who experienced déjà vu were younger and more educated than persons who had not experienced it. There were no differences in the frequency of déjà vu experiences based on sex, hand preference, or area of residence. Subsequent factor analysis associated déjà vu with precognitive dreams and remembering dreams as dream- and memory-related factors rather than with the dissociation-related factors of depersonalization, derealization, jamais vu, and daydreams or with mental activity-related factors such as paranormal quality and travel frequency. Results suggest that déjà vu experiences are associated with good memory function.