title: Hippocampal activation associated with successful external source monitoring.
abstract: Studies demonstrating hippocampal activation associated with memories for persons from whom information is acquired (external source monitoring) are lacking. In this study, we used functional magnetic resonance imaging (fMRI) to investigate whether the medial temporal lobe (MTL), especially the hippocampus, is activated during the retrieval of external source information as well as during the retrieval of the items themselves. Before the fMRI, subjects intentionally studied photographs with names that were presented by either a woman or a man in a videotape. During the fMRI, subjects were asked to judge whether each photograph was new or old and, if they judged it as old, to indicate which person had presented the photograph during the study phase according to a confidence rating (high or low). The results showed that successful retrieval of a source with high confidence was associated with increased activity in the hippocampus and that correct item recognition with failed source retrieval and low confidence for a source (i.e., item-only hits) was associated with decreased activity in the perirhinal cortex. Further analysis revealed that the hippocampus was also associated with familiarity/novelty distinction for the items themselves. The present study is the first to provide evidence that hippocampal activation is associated with external source monitoring. The results also support existing models suggesting that the hippocampus is associated with recollection-based recognition and the perirhinal cortex with familiarity-based recognition, with the possibility that the hippocampus plays roles in both recognition processes.
authors.affiliation: Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Shunji
authors.initials: S
authors.lastname: Mugikura
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Abe
authors.forename: Maki
authors.initials: M
authors.lastname: Suzuki
authors.forename: Aya
authors.initials: A
authors.lastname: Ueno
authors.forename: Shuichi
authors.initials: S
authors.lastname: Higano
authors.forename: Shoki
authors.initials: S
authors.lastname: Takahashi
authors.forename: Toshikatsu
authors.initials: T
authors.lastname: Fujii
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D006624:Hippocampus / Q000098:blood supply / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D021641:Recognition, Psychology / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen