Premium
Semantic retrieval over time in the aging brain: Structural evidence of hippocampal contribution
Author(s) -
Catheline Gwénaëlle,
Amieva Hélène,
Dilharreguy Bixente,
Bernard Charlotte,
Duperron MarieGabrielle,
Helmer Catherine,
Dartigues JeanFrançois,
Allard Michèle
Publication year - 2015
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.22423
Subject(s) - psychology , hippocampus , verbal fluency test , grey matter , audiology , neuroscience , semantic memory , voxel based morphometry , cognition , cognitive psychology , voxel , white matter , neuropsychology , magnetic resonance imaging , medicine , artificial intelligence , computer science , radiology
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. © 2015 Wiley Periodicals, Inc.