Abstract
IntroductionMorphological 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.MethodsUsing 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.ResultsSignificant 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.ConclusionsOur 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.
Highlights
Morphological correlates of nonpathological déjà vu (DV) have been identified recently within the human brain
Using highly sensitive source-based morphometry to investigate a large cohort of healthy subjects, significantly reduced gray matter volume (GMV) was revealed within bilateral mesiotemporal regions, insular cortices, superior temporal sulci, basal ganglia and thalami in subjects reporting prior experience of DV compared to those reporting no such experience
Based on reports of high neuroanatomical similarity in healthy individuals reporting nonpathological DV and mesial temporal lobe epilepsy (MTLE) patients in whom pathological DV occurs frequently, we hypothesized that patterns of GMV reduction across hippocampal subfields in the DV+ group would resemble those measured in MTLE but differ from those observed in the SCH group with a more complex pattern of clinical presentation and distinct underlying hippocampal neuropathology
Summary
Déjà vu (DV) is a complex phenomenon of erroneous familiarity. When experienced by up to 76% of the healthy population (Adachi et al, 2003), DV is believed to reflect aberrant yet nonpathological brain function among memory-related neural systems (Shaw, Mareček, & Brázdil, 2015). Impaired hippocampal recruitment during the memory recall (Heckers et al, 1998; Weiss et al, 2003) combined with attribution of strong behavioral importance to stimuli that would be otherwise safely ignored (termed “aberrant salience”) is suggested to potentially underlie delusional or hallucinatory states in schizophrenia (Kapur, 2003) This concept of providing irrelevant context to currently processed percepts/cognitions corresponds with one of the widely accepted theories considering mechanisms behind déjà vu. The question is whether the morphological correlate of nonpathological DV in terms of hippocampal subfields converges with this one of MTLE as a condition with corresponding morphological correlate in various sites of the brain or with the schizophrenia which carries similar concept considering underlying mechanisms To answer this inquiry and to define the precise involvement of the hippocampus in DV, we used automated segmentation to assess and compare GMV across the hippocampal subfields in four patient groups. Based on reports of high neuroanatomical similarity in healthy individuals reporting nonpathological DV and MTLE patients in whom pathological DV occurs frequently, we hypothesized that patterns of GMV reduction across hippocampal subfields in the DV+ group would resemble those measured in MTLE but differ from those observed in the SCH group with a more complex pattern of clinical presentation and distinct underlying hippocampal neuropathology
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
