Rhinal–hippocampal interactions during déjà vu

ObjectiveThe phenomenon of ‘déjà vu’ is caused by acute disturbance of mnemonic systems of the medial temporal lobe (MTL). In epileptic patients investigated with intracerebral electrodes, déjà vu can be more readily induced by stimulation of the rhinal cortices (RCs) than the hippocampus (H). Whether déjà vu results from acute dysfunction of the familiarity system alone (sustained by RC) or from more extensive involvement of the MTL region (including H) is debatable.MethodsWe analysed the synchronisation of intracerebral electroencephalography (EEG) signals recorded from RC, H and amygdala (A) in epileptic patients in whom déjà vu was induced by electrical stimulation.EEG signal correlations (between signals from RC, A and H) were evaluated using a nonlinear regression.ResultsIn comparison with RC stimulations that did not lead to déjà vu (DV−), stimulations triggering déjà vu (DV+) were associated with increased broadband EEG correlation (p = 0.01). Changes in correlations were significantly different in the theta band for RC–A (p = 0.007) and RC–H (p = 0.01) and in the beta band for RC–H (p = 0.001) interactions.ConclusionDéjà vu is associated with increased EEG signal correlation between MTL structures.SignificanceResults are in favour of a mechanism involving transient co-operation between various MTL structures, not limited to RC alone.

► The phenomenon of déjà vu is caused by acute disturbance of mnemonic systems of the medial temporal lobe (MTL). ► In epileptic patients investigated with intracerebral electrodes, déjà vu can be more readily induced by stimulation of the rhinal cortices than the hippocampus. ► This study is the first to report the signal correlations of intracerebral EEG signals between MTL structures during déjà vu, demonstrating large collaboration between these brain structures.