Novel insights into false recollection: a model of déjà vécu

The thesis of this paper is that déjà experiences can be separated into two forms: déjà vu, arising from the erroneous sensation of familiarity, and déjà vécu, arising from the erroneous sensation of recollection. We summarise a series of cases for whom déjà vécu is experienced frequently and for extended periods, and seek to differentiate their experiences from "healthy" déjà experiences by non-brain-damaged participants. In reviewing our cases, we stress two novel ideas: that déjà vécu in these cases is delusion-like; and that these cases experience déjà vécu for stimuli that are especially novel or unusual. Here we present a novel cognitive neuroscientific hypothesis of déjà vécu. This hypothesis assumes that the signal of retrieval from memory is neurally dissociable from the contents of retrieval. We suggest that a region downstream of the hippocampus signals "recollection" by detecting the timing of firing in hippocampal output neurons relative to the theta oscillation. Disruptions to this "temporal coding" mechanism result in false signals of recollection which may occur without actual retrieval and which, ironically, may arise particularly during situations of contextual novelty.