title: Neural correlates of training and transfer effects in working memory in older adults.
abstract: As indicated by previous research, aging is associated with a decline in working memory (WM) functioning, related to alterations in fronto-parietal neural activations. At the same time, previous studies showed that WM training in older adults may improve the performance in the trained task (training effect), and more importantly, also in untrained WM tasks (transfer effects). However, neural correlates of these transfer effects that would improve understanding of its underlying mechanisms, have not been shown in older participants as yet. In this study, we investigated blood-oxygen-level-dependent (BOLD) signal changes during n-back performance and an untrained delayed recognition (Sternberg) task following 12sessions (45min each) of adaptive n-back training in older adults. The Sternberg task used in this study allowed to test for neural training effects independent of specific task affordances of the trained task and to separate maintenance from updating processes. Thirty-two healthy older participants (60-75years) were assigned either to an n-back training or a no-contact control group. Before (t1) and after (t2) training/waiting period, both the n-back task and the Sternberg task were conducted while BOLD signal was measured using functional Magnetic Resonance Imaging (fMRI) in all participants. In addition, neuropsychological tests were performed outside the scanner. WM performance improved with training and behavioral transfer to tests measuring executive functions, processing speed, and fluid intelligence was found. In the training group, BOLD signal in the right lateral middle frontal gyrus/caudal superior frontal sulcus (Brodmann area, BA 6/8) decreased in both the trained n-back and the updating condition of the untrained Sternberg task at t2, compared to the control group. fMRI findings indicate a training-related increase in processing efficiency of WM networks, potentially related to the process of WM updating. Performance gains in untrained tasks suggest that transfer to other cognitive tasks remains possible in aging.
authors.affiliation: Department of Psychology, Humboldt-Universität zu Berlin, Rudower Chaussee 18, 12489 Berlin, Germany; Social and Preventive Medicine, University of Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany; Berlin Center for Advanced Neuroimaging, Berlin, Germany; Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany. Electronic address: stephan.heinzel@hu-berlin.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Heinzel
authors.affiliation: Department of Psychology, Humboldt-Universität zu Berlin, Rudower Chaussee 18, 12489 Berlin, Germany; Berlin Center for Advanced Neuroimaging, Berlin, Germany; Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Max Planck Institute for Human Development, Lentzeallee 94, 14195 Berlin, Germany.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Lorenz
authors.affiliation: Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Patricia
authors.initials: P
authors.lastname: Pelz
authors.affiliation: Berlin Center for Advanced Neuroimaging, Berlin, Germany; Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Heinz
authors.affiliation: Berlin Center for Advanced Neuroimaging, Berlin, Germany; Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Berlin School of Mind and Brain, Germany.
authors.forename: Henrik
authors.initials: H
authors.lastname: Walter
authors.affiliation: Department of Psychology, Humboldt-Universität zu Berlin, Rudower Chaussee 18, 12489 Berlin, Germany; Berlin Center for Advanced Neuroimaging, Berlin, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Kathmann
authors.affiliation: Social and Preventive Medicine, University of Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany; Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Rapp
authors.affiliation: Department of Psychology, Humboldt-Universität zu Berlin, Rudower Chaussee 18, 12489 Berlin, Germany; Social and Preventive Medicine, University of Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany; Berlin Center for Advanced Neuroimaging, Berlin, Germany; Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Berlin School of Mind and Brain, Germany; International Psychoanalytic University, Stromstr. 1, 10555 Berlin, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Stelzel
mesh_terms: D000368:Aged; D000375:Aging; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D009473:Neuronal Plasticity / Q000502:physiology; D013647:Task Performance and Analysis; D014163:Transfer, Psychology / Q000502:physiology*
keywords: Aging; Executive functions; Fluid intelligence; Neuroimaging; Training; Transfer; Updating; Working memory; fMRI