title: Semantic retrieval over time in the aging brain: Structural evidence of hippocampal contribution.
abstract: This study investigates relationship between regional cerebral volumes and performances over time of a categorical fluency task, in a sample of older adults (n = 316). Using voxel-wise technique, the relationship between local grey matter volume and Isaacs Set Test (IST) scores at its early (first 15 sec) and late (last 15 sec) phase production was analyzed with a linear regression model adjusting for age, sex, educational level, ApoEɛ4 allele, handedness and Grey Matter atrophy. Lower early IST scores were associated with smaller volumes in bilateral inferior frontal gyri and in right thalamus, whereas lower late IST scores were associated to smaller left inferior parietal gyrus and left anterior hippocampus. An analysis based on automatic segmentation of hippocampus confirmed the latest relationship which cannot be attributed to the correlation of each variable with global cognitive impairment because it remained when MMSE was accounted for. We observed a switch from frontal to temporo-parietal regions as words retrieval become more difficult over time. Automatic speech production of the early phase of the category fluency task is dependent on executive networks integrity whereas controlled speech production of the late phase is dependent on memory networks integrity, including left hippocampus. These results are concordant with recent imaging studies expanding the implication of hippocampus to semantic memory performances and they underlie the need to consider verbal fluency task over time.
authors.affiliation: Univ. Bordeaux, INCIA, UMR 5287, Talence, France.|CNRS, INCIA, UMR 5287, Talence, France.|EPHE, Paris, France.
authors.forename: Gwénaëlle
authors.initials: G
authors.lastname: Catheline
authors.affiliation: ISPED, Université de Bordeaux, Bordeaux, France.|Centre de Recherche Inserm U897, Bordeaux, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Amieva
authors.affiliation: Univ. Bordeaux, INCIA, UMR 5287, Talence, France.|CNRS, INCIA, UMR 5287, Talence, France.
authors.forename: Bixente
authors.initials: B
authors.lastname: Dilharreguy
authors.affiliation: Univ. Bordeaux, INCIA, UMR 5287, Talence, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Bernard
authors.affiliation: Univ. Bordeaux, INCIA, UMR 5287, Talence, France.
authors.forename: Marie-Gabrielle
authors.initials: MG
authors.lastname: Duperron
authors.affiliation: ISPED, Université de Bordeaux, Bordeaux, France.|Centre de Recherche Inserm U897, Bordeaux, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Helmer
authors.affiliation: ISPED, Université de Bordeaux, Bordeaux, France.|Centre de Recherche Inserm U897, Bordeaux, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Dartigues
authors.affiliation: Univ. Bordeaux, INCIA, UMR 5287, Talence, France.|CNRS, INCIA, UMR 5287, Talence, France.|EPHE, Paris, France.|Chu de Bordeaux, France.
authors.forename: Michèle
authors.initials: M
authors.lastname: Allard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001057:Apolipoproteins E / Q000235:genetics; D015331:Cohort Studies; D005260:Female; D006624:Hippocampus / Q000033:anatomy & histology* / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D012660:Semantics; D013997:Time Factors; D014706:Verbal Learning / Q000502:physiology
chemical_list: D001057:Apolipoproteins E
keywords: VBM; aging; category verbal fluency; semantic verbal fluency; words retrieval