title: fMRI congruous word repetition effects reflect memory variability in normal elderly.
abstract: Neural circuits mediating repetition effect for semantically congruous words on functional MRI were investigated in seventeen normal elderly (mean age=70). Participants determined if written words were semantically congruent (50% probability) with spoken statements. Subsequent cued-recall revealed robust explicit memory only for congruous items (83% versus 8% for incongruous). Event-related BOLD responses to New>Old congruous words were found in the left>right cingulate and fusiform gyri, left parahippocampal cortex, middle and inferior frontal gyri (IFG). A group with above-median subsequent recall had markedly more widespread BOLD responses than a Low-Recall subgroup, with larger responses in the left medial temporal lobe (LMTL), IFG, and bilateral cingulate gyri. The magnitude of LMTL activation (New-Old) correlated with subsequent cued-recall, while the spatial extent of LMTL activation (New>Old) correlated with recall and recognition. Both magnitude and spatial extent of left fusiform activation correlated with subsequent recall/recognition. A neural circuit of left-hemisphere brain regions, many identified as P600 generators by invasive electrophysiological studies, was activated by New>Old congruous words, likely mediating successful verbal encoding.
authors.affiliation: Department of Neurology, University of California, Davis, 4860 Y St. Sacramento, CA 95817, USA. jmolichney@ucdavis.edu
authors.forename: John M
authors.initials: JM
authors.lastname: Olichney
authors.forename: Jason R
authors.initials: JR
authors.lastname: Taylor
authors.forename: Dieter G
authors.initials: DG
authors.lastname: Hillert
authors.forename: Shiao-Hui
authors.initials: SH
authors.lastname: Chan
authors.forename: David P
authors.initials: DP
authors.lastname: Salmon
authors.forename: James
authors.initials: J
authors.lastname: Gatherwright
authors.forename: Vicente J
authors.initials: VJ
authors.lastname: Iragui
authors.forename: Marta
authors.initials: M
authors.lastname: Kutas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000502:physiology*; D021641:Recognition, Psychology / Q000502:physiology*; D012016:Reference Values; D012660:Semantics; D014705:Verbal Behavior / Q000502:physiology*; D014706:Verbal Learning / Q000502:physiology*