@article{HeinzelLorenzBrockhausetal.2014,
  author    = {Heinzel, Stephan and Lorenz, Robert C. and Brockhaus, Wolf-Ruediger and Wuestenberg, Torsten and Kathmann, Norbert and Heinz, Andreas and Rapp, Michael Armin},
  title     = {Working memory load-dependent brain response predicts behavioral training gains in older adults},
  series = {The journal of neuroscience},
  volume    = {34},
  journal   = {The journal of neuroscience},
  number    = {4},
  publisher = {Society for Neuroscience},
  address   = {Washington},
  issn      = {0270-6474},
  doi       = {10.1523/JNEUROSCI.2463-13.2014},
  pages     = {1224 -- 1233},
  year      = {2014},
  abstract  = {In the domain of working memory (WM), a sigmoid-shaped relationship between WM load and brain activation patterns has been demonstrated in younger adults. It has been suggested that age-related alterations of this pattern are associated with changes in neural efficiency and capacity. At the same time, WM training studies have shown that some older adults are able to increase their WM performance through training. In this study, functional magnetic resonance imaging during an n-back WM task at different WM load levels was applied to compare blood oxygen level-dependent (BOLD) responses between younger and older participants and to predict gains in WM performance after a subsequent 12-session WM training procedure in older adults. We show that increased neural efficiency and capacity, as reflected by more "youth-like" brain response patterns in regions of interest of the frontoparietal WM network, were associated with better behavioral training outcome beyond the effects of age, sex, education, gray matter volume, and baseline WM performance. Furthermore, at low difficulty levels, decreases in BOLD response were found after WM training. Results indicate that both neural efficiency (i. e., decreased activation at comparable performance levels) and capacity (i. e., increasing activation with increasing WM load) of a WM-related network predict plasticity of the WM system, whereas WM training may specifically increase neural efficiency in older adults.},
  language  = {en}
}
@article{HeinzelRiemerSchulteetal.2014,
  author    = {Heinzel, Stephan and Riemer, Thomas G. and Schulte, Stefanie and Onken, Johanna and Heinz, Andreas and Rapp, Michael Armin},
  title     = {Catechol-O-methyltransferase (COMT) genotype affects age-related changes in plasticity in working memory: a pilot study},
  series = {BioMed research international},
  journal   = {BioMed research international},
  publisher = {Hindawi Publishing Corp.},
  address   = {New York},
  issn      = {2314-6133},
  doi       = {10.1155/2014/414351},
  pages     = {7},
  year      = {2014},
  abstract  = {Objectives. Recent work suggests that a genetic variation associated with increased dopamine metabolism in the prefrontal cortex (catechol-O-methyltransferase Val158Met; COMT) amplifies age-related changes in working memory performance. Research on younger adults indicates that the influence of dopamine-related genetic polymorphisms on working memory performance increases when testing the cognitive limits through training. To date, this has not been studied in older adults. Method. Here we investigate the effect of COMT genotype on plasticity in working memory in a sample of 14 younger (aged 24-30 years) and 25 older (aged 60-75 years) healthy adults. Participants underwent adaptive training in the n-back working memory task over 12 sessions under increasing difficulty conditions. Results. Both younger and older adults exhibited sizeable behavioral plasticity through training (P < .001), which was larger in younger as compared to older adults (P < .001). Age-related differences were qualified by an interaction with COMT genotype (P < .001), and this interaction was due to decreased behavioral plasticity in older adults carrying the Val/Val genotype, while there was no effect of genotype in younger adults. Discussion. Our findings indicate that age-related changes in plasticity in working memory are critically affected by genetic variation in prefrontal dopamine metabolism.},
  language  = {en}
}