title: Working memory activation of neural networks in the elderly as a function of information processing phase and task complexity.
abstract: Changes in working memory are sensitive indicators of both normal and pathological brain aging and associated disability. The present study aims to further understanding of working memory in normal aging using a large cohort of healthy elderly in order to examine three separate phases of information processing in relation to changes in task load activation. Using covariance analysis, increasing and decreasing neural activation was observed on fMRI in response to a delayed item recognition task in 337 cognitively healthy elderly persons as part of the CRESCENDO (Cognitive REServe and Clinical ENDOphenotypes) study. During three phases of the task (stimulation, retention, probe), increased activation was observed with increasing task load in bilateral regions of the prefrontal cortex, parietal lobule, cingulate gyrus, insula and in deep gray matter nuclei, suggesting an involvement of central executive and salience networks. Decreased activation associated with increasing task load was observed during the stimulation phase, in bilateral temporal cortex, parietal lobule, cingulate gyrus and prefrontal cortex. This spatial distribution of decreased activation is suggestive of the default mode network. These findings support the hypothesis of an increased activation in salience and central executive networks and a decreased activation in default mode network concomitant to increasing task load.
authors.affiliation: Institut d'Imagerie Fonctionnelle Humaine, I2FH, Department of Neuroradiology, Montpellier University Hospital Center, Gui de Chauliac Hospital, University of Montpellier, Montpellier, France; Inserm, Unit 1198, Molecular Mechanisms in Neurodegenerative Diseases, University of Montpellier, Montpellier, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Charroud
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology, Columbia University, New York, United States.
authors.forename: Jason
authors.initials: J
authors.lastname: Steffener
authors.affiliation: Institut d'Imagerie Fonctionnelle Humaine, I2FH, Department of Neuroradiology, Montpellier University Hospital Center, Gui de Chauliac Hospital, University of Montpellier, Montpellier, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Le Bars
authors.affiliation: Institut d'Imagerie Fonctionnelle Humaine, I2FH, Department of Neuroradiology, Montpellier University Hospital Center, Gui de Chauliac Hospital, University of Montpellier, Montpellier, France; Laboratoire Charles Coulomb, CNRS UMR 5221, University of Montpellier, Montpellier, France; Intrasense, Montpellier, France.
authors.forename: Jérémy
authors.initials: J
authors.lastname: Deverdun
authors.affiliation: Institut d'Imagerie Fonctionnelle Humaine, I2FH, Department of Neuroradiology, Montpellier University Hospital Center, Gui de Chauliac Hospital, University of Montpellier, Montpellier, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Bonafe
authors.affiliation: Inserm, Unit 1061, Neuropsychiatry: Epidemiological and Clinical Research, La Colombière Hospital, University of Montpellier, Montpellier, France.
authors.forename: Meriem
authors.initials: M
authors.lastname: Abdennour
authors.affiliation: Inserm, Unit 1061, Neuropsychiatry: Epidemiological and Clinical Research, La Colombière Hospital, University of Montpellier, Montpellier, France; Montpellier University Hospital, Department of Adult Psychiatry, La Colombière Hospital, Montpellier, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Portet
authors.affiliation: Laboratoire Charles Coulomb, CNRS UMR 5221, University of Montpellier, Montpellier, France; Institut de Génomique Fonctionnelle, UMR 5203, INSERM U661, University of Montpellier, Montpellier, France.
authors.forename: François
authors.initials: F
authors.lastname: Molino
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology, Columbia University, New York, United States.
authors.forename: Yaakov
authors.initials: Y
authors.lastname: Stern
authors.affiliation: Inserm, Unit 1061, Neuropsychiatry: Epidemiological and Clinical Research, La Colombière Hospital, University of Montpellier, Montpellier, France; University of Montpellier, Montpellier, France; Faculty of Medicine, Imperial College, London, United Kingdom.
authors.forename: Karen
authors.initials: K
authors.lastname: Ritchie
authors.affiliation: Institut d'Imagerie Fonctionnelle Humaine, I2FH, Department of Neuroradiology, Montpellier University Hospital Center, Gui de Chauliac Hospital, University of Montpellier, Montpellier, France; Team "Plasticity of Central Nervous System, Stem Cells and Glial Tumors", U1051, Institut of Neurosciences of Montpellier, Saint Eloi Hospital, Montpellier, France. Electronic address: nicolasdechampfleur@orange.fr.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Menjot de Champfleur
authors.affiliation: Inserm, Unit 1198, Molecular Mechanisms in Neurodegenerative Diseases, University of Montpellier, Montpellier, France; Department of Epidemiology and Public Health, University College London, London, United Kingdom.
authors.forename: Tasnime N
authors.initials: TN
authors.lastname: Akbaraly
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology* / Q000523:psychology; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D021641:Recognition, Psychology / Q000502:physiology*
keywords: Aging; Functional MRI; Memory: working memory; Neuroimaging