@article{DesernoBeckHuysetal.2015, author = {Deserno, Lorenz and Beck, Anne and Huys, Quentin J. M. and Lorenz, Robert C. and Buchert, Ralph and Buchholz, Hans-Georg and Plotkin, Michail and Kumakara, Yoshitaka and Cumming, Paul and Heinze, Hans-Jochen and Grace, Anthony A. and Rapp, Michael A. and Schlagenhauf, Florian and Heinz, Andreas}, title = {Chronic alcohol intake abolishes the relationship between dopamine synthesis capacity and learning signals in the ventral striatum}, series = {European journal of neuroscience}, volume = {41}, journal = {European journal of neuroscience}, number = {4}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0953-816X}, doi = {10.1111/ejn.12802}, pages = {477 -- 486}, year = {2015}, abstract = {Drugs of abuse elicit dopamine release in the ventral striatum, possibly biasing dopamine-driven reinforcement learning towards drug-related reward at the expense of non-drug-related reward. Indeed, in alcohol-dependent patients, reactivity in dopaminergic target areas is shifted from non-drug-related stimuli towards drug-related stimuli. Such hijacked' dopamine signals may impair flexible learning from non-drug-related rewards, and thus promote craving for the drug of abuse. Here, we used functional magnetic resonance imaging to measure ventral striatal activation by reward prediction errors (RPEs) during a probabilistic reversal learning task in recently detoxified alcohol-dependent patients and healthy controls (N=27). All participants also underwent 6-[F-18]fluoro-DOPA positron emission tomography to assess ventral striatal dopamine synthesis capacity. Neither ventral striatal activation by RPEs nor striatal dopamine synthesis capacity differed between groups. However, ventral striatal coding of RPEs correlated inversely with craving in patients. Furthermore, we found a negative correlation between ventral striatal coding of RPEs and dopamine synthesis capacity in healthy controls, but not in alcohol-dependent patients. Moderator analyses showed that the magnitude of the association between dopamine synthesis capacity and RPE coding depended on the amount of chronic, habitual alcohol intake. Despite the relatively small sample size, a power analysis supports the reported results. Using a multimodal imaging approach, this study suggests that dopaminergic modulation of neural learning signals is disrupted in alcohol dependence in proportion to long-term alcohol intake of patients. Alcohol intake may perpetuate itself by interfering with dopaminergic modulation of neural learning signals in the ventral striatum, thus increasing craving for habitual drug intake.}, language = {en} } @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 A.}, 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{HeinzelLorenzPelzetal.2016, author = {Heinzel, Stephan and Lorenz, Robert C. and Pelz, Patricia and Heinz, Andreas and Walter, Henrik and Kathmann, Norbert and Rapp, Michael A. and Stelzel, Christine}, title = {Neural correlates of training and transfer effects in working memory in older adults}, series = {NeuroImage : a journal of brain function}, volume = {134}, journal = {NeuroImage : a journal of brain function}, publisher = {Elsevier}, address = {San Diego}, issn = {1053-8119}, doi = {10.1016/j.neuroimage.2016.03.068}, pages = {236 -- 249}, year = {2016}, 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 12 sessions (45 min 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 (60-75 years) 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. (C) 2016 Elsevier Inc. All rights reserved.}, language = {en} } @article{LorenzGleichBecketal.2014, author = {Lorenz, Robert C. and Gleich, Tobias and Beck, Anne and Poehland, Lydia and Raufelder, Diana and Sommer, Werner and Rapp, Michael A. and Kuehn, Simone and Gallinat, J{\"u}rgen}, title = {Reward anticipation in the adolescent and aging brain}, series = {Human brain mapping : a journal devoted to functional neuroanatomy and neuroimaging}, volume = {35}, journal = {Human brain mapping : a journal devoted to functional neuroanatomy and neuroimaging}, number = {10}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1065-9471}, doi = {10.1002/hbm.22540}, pages = {5153 -- 5165}, year = {2014}, abstract = {Processing of reward is the basis of adaptive behavior of the human being. Neural correlates of reward processing seem to be influenced by developmental changes from adolescence to late adulthood. The aim of this study is to uncover these neural correlates during a slot machine gambling task across the lifespan. Therefore, we used functional magnetic resonance imaging to investigate 102 volunteers in three different age groups: 34 adolescents, 34 younger adults, and 34 older adults. We focused on the core reward areas ventral striatum (VS) and ventromedial prefrontal cortex (VMPFC), the valence processing associated areas, anterior cingulate cortex (ACC) and insula, as well as information integration associated areas, dorsolateral prefrontal cortex (DLPFC), and inferior parietal lobule (IPL). Results showed that VS and VMPFC were characterized by a hyperactivation in adolescents compared with younger adults. Furthermore, the ACC and insula were characterized by a U-shape pattern (hypoactivation in younger adults compared with adolescents and older adults), whereas the DLPFC and IPL were characterized by a J-shaped form (hyperactivation in older adults compared with younger groups). Furthermore, a functional connectivity analysis revealed an elevated negative functional coupling between the inhibition-related area rIFG and VS in younger adults compared with adolescents. Results indicate that lifespan-related changes during reward anticipation are characterized by different trajectories in different reward network modules and support the hypothesis of an imbalance in maturation of striatal and prefrontal cortex in adolescents. Furthermore, these results suggest compensatory age-specific effects in fronto-parietal regions. Hum Brain Mapp 35:5153-5165, 2014. (c) 2014 Wiley Periodicals, Inc.}, language = {en} }