title: Implicit associative learning engages the hippocampus and interacts with explicit associative learning.
abstract: The hippocampus is crucial for conscious, explicit memory, but whether it is also involved in nonconscious, implicit memory is uncertain. We investigated with functional magnetic resonance imaging whether implicit learning engages the hippocampus and interacts with subsequent explicit learning. The presentation of subliminal faces-written profession pairs for implicit learning was followed by the explicit learning of supraliminal pairs composed of the same faces combined with written professions semantically incongruous to those presented subliminally (experiment 1), semantically congruous professions (experiment 2), or identical professions (experiment 3). We found that implicit face-profession learning interacted with explicit face-profession learning in all experiments, impairing the explicit retrieval of the associations. Hippocampal activity increased during the subliminal presentation of face-profession pairs versus face-nonword pairs and correlated with the later impairment of explicit retrieval. These findings suggest that implicit semantic associative learning engages the hippocampus and influences explicit memory.
authors.affiliation: Division of Psychiatry Research, University of Zurich, Switzerland.
authors.forename: Nadia
authors.initials: N
authors.lastname: Degonda
authors.forename: Christian R A
authors.initials: CR
authors.lastname: Mondadori
authors.forename: Simone
authors.initials: S
authors.lastname: Bosshardt
authors.forename: Conny F
authors.initials: CF
authors.lastname: Schmidt
authors.forename: Peter
authors.initials: P
authors.lastname: Boesiger
authors.forename: Roger M
authors.initials: RM
authors.lastname: Nitsch
authors.forename: Christoph
authors.initials: C
authors.lastname: Hock
authors.forename: Katharina
authors.initials: K
authors.lastname: Henke
mesh_terms: D001245:Association Learning / Q000502:physiology*; D001931:Brain Mapping; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D010775:Photic Stimulation; D013360:Subliminal Stimulation; D014796:Visual Perception