Data from: Hippocampus is place of interaction between unconscious and conscious memories

Recent evidence suggests that humans can form and later retrieve new
semantic relations unconsciously by way of hippocampus—the key structure
also recruited for conscious relational (episodic) memory. If the
hippocampus subserves both conscious and unconscious relational
encoding/retrieval, one would expect the hippocampus to be place of
unconscious-conscious interactions during memory retrieval. We tested this
hypothesis in an fMRI experiment probing the interaction between the
unconscious and conscious retrieval of face-associated information. For
the establishment of unconscious relational memories, we presented
subliminal (masked) combinations of unfamiliar faces and written
occupations (“actor” or “politician”). At test, we presented the former
subliminal faces, but now supraliminally, as cues for the reactivation of
the unconsciously associated occupations. We hypothesized that unconscious
reactivation of the associated occupation—actor or politician—would
facilitate or inhibit the subsequent conscious retrieval of a celebrity’s
occupation, which was also actor or politician. Depending on whether the
reactivated unconscious occupation was congruent or incongruent to the
celebrity’s occupation, we expected either quicker or delayed conscious
retrieval process. Conscious retrieval was quicker in the congruent
relative to a neutral baseline condition but not delayed in the
incongruent condition. fMRI data collected during subliminal
face-occupation encoding confirmed previous evidence that the hippocampus
was interacting with neocortical storage sites of semantic knowledge to
support relational encoding. fMRI data collected at test revealed that the
facilitated conscious retrieval was paralleled by deactivations in the
hippocampus and neocortical storage sites of semantic knowledge. We assume
that the unconscious reactivation has pre-activated overlapping relational
representations in the hippocampus reducing the neural effort for
conscious retrieval. This finding supports the notion of synergistic
interactions between conscious and unconscious relational memories in a
common, cohesive hippocampal-neocortical memory space.