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  • 1
    Online Resource
    Online Resource
    Load Modulation of BOLD Response and Connectivity Predicts Working Memory Performance in Younger and Older Adults
    MIT Press ; 2011
    In:  Journal of Cognitive Neuroscience Vol. 23, No. 8 ( 2011-08-01), p. 2030-2045
    Details
    In: Journal of Cognitive Neuroscience, MIT Press, Vol. 23, No. 8 ( 2011-08-01), p. 2030-2045
    Abstract: Individual differences in working memory (WM) performance have rarely been related to individual differences in the functional responsivity of the WM brain network. By neglecting person-to-person variation, comparisons of network activity between younger and older adults using functional imaging techniques often confound differences in activity with age trends in WM performance. Using functional magnetic resonance imaging, we investigated the relations among WM performance, neural activity in the WM network, and adult age using a parametric letter n-back task in 30 younger adults (21–31 years) and 30 older adults (60–71 years). Individual differences in the WM network's responsivity to increasing task difficulty were related to WM performance, with a more responsive BOLD signal predicting greater WM proficiency. Furthermore, individuals with higher WM performance showed greater change in connectivity between left dorsolateral prefrontal cortex and left premotor cortex across load. We conclude that a more responsive WM network contributes to higher WM performance, regardless of adult age. Our results support the notion that individual differences in WM performance are important to consider when studying the WM network, particularly in age-comparative studies.
    Type of Medium: Online Resource
    ISSN: 0898-929X , 1530-8898
    URL: Article
    DOI: 10.1162/jocn.2010.21560
    Language: English
    Publisher: MIT Press
    Publication Date: 2011
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  • 2
    Online Resource
    Online Resource
    Dopaminergic Gene Polymorphisms Affect Long-term Forgetting in Old Age: Further Support for the Magnification Hypothesis
    MIT Press ; 2013
    In:  Journal of Cognitive Neuroscience Vol. 25, No. 4 ( 2013-04-01), p. 571-579
    Details
    In: Journal of Cognitive Neuroscience, MIT Press, Vol. 25, No. 4 ( 2013-04-01), p. 571-579
    Abstract: Emerging evidence from animal studies suggests that suboptimal dopamine (DA) modulation may be associated with increased forgetting of episodic information. Extending these observations, we investigated the influence of DA-relevant genes on forgetting in samples of younger (n = 433, 20–31 years) and older (n = 690, 59–71 years) adults. The effects of single nucleotide polymorphisms of the DA D2 (DRD2) and D3 (DRD3) receptor genes as well as the DA transporter gene (DAT1; SLC6A3) were examined. Over the course of one week, older adults carrying two or three genotypes associated with higher DA signaling (i.e., higher availability of DA and DA receptors) forgot less pictorial information than older individuals carrying only one or no beneficial genotype. No such genetic effects were found in younger adults. The results are consistent with the view that genetic effects on cognition are magnified in old age. To the best of our knowledge, this is the first report to relate genotypes associated with suboptimal DA modulation to more long-term forgetting in humans. Independent replication studies in other populations are needed to confirm the observed association.
    Type of Medium: Online Resource
    ISSN: 0898-929X , 1530-8898
    URL: Article
    DOI: 10.1162/jocn_a_00359
    Language: English
    Publisher: MIT Press
    Publication Date: 2013
    SSG: 5,2
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  • 3
    Online Resource
    Online Resource
    Development of attentional control of verbal auditory perception from middle to late childhood: Comparisons to healthy aging.
    American Psychological Association (APA) ; 2013
    In:  Developmental Psychology Vol. 49, No. 10 ( 2013-10), p. 1982-1993
    Details
    In: Developmental Psychology, American Psychological Association (APA), Vol. 49, No. 10 ( 2013-10), p. 1982-1993
    Type of Medium: Online Resource
    ISSN: 1939-0599 , 0012-1649
    URL: Article
    DOI: 10.1037/a0031207
    Language: English
    Publisher: American Psychological Association (APA)
    Publication Date: 2013
    detail.hit.zdb_id: 2066223-3
    SSG: 5,2
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  • 4
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    Performance level modulates adult age differences in brain activation during spatial working memory
    Proceedings of the National Academy of Sciences ; 2009
    In:  Proceedings of the National Academy of Sciences Vol. 106, No. 52 ( 2009-12-29), p. 22552-22557
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 106, No. 52 ( 2009-12-29), p. 22552-22557
    Abstract: Working memory (WM) shows pronounced age-related decline. Functional magnetic resonance imaging (fMRI) studies have revealed age differences in task-related brain activation. Evidence based primarily on episodic memory studies suggests that brain activation patterns can be modulated by task difficulty in both younger and older adults. In most fMRI aging studies on WM, however, performance level has not been considered, so that age differences in activation patterns are confounded with age differences in performance level. Here, we address this issue by comparing younger and older low and high performers in an event-related fMRI study. Thirty younger (20–30 years) and 30 older (60–70 years) healthy adults were tested with a spatial WM task with three load levels. A region-of-interest analysis revealed marked differences in the activation patterns between high and low performers in both age groups. Critically, among the older adults, a more “youth-like” load-dependent modulation of the blood oxygen level-dependent signal was associated with higher levels of spatial WM performance. These findings underscore the need of taking performance level into account when studying changes in functional brain activation patterns from early to late adulthood.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0908238106
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2009
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  • 5
    Online Resource
    Online Resource
    Ebbinghaus Revisited: Influences of the BDNF Val 66 Met Polymorphism on Backward Serial Recall Are Modulated by Human Aging
    MIT Press ; 2010
    In:  Journal of Cognitive Neuroscience Vol. 22, No. 10 ( 2010-10-01), p. 2164-2173
    Details
    In: Journal of Cognitive Neuroscience, MIT Press, Vol. 22, No. 10 ( 2010-10-01), p. 2164-2173
    Abstract: The brain-derived neurotrophic factor (BDNF) plays an important role in activity-dependent synaptic plasticity, which underlies learning and memory. In a sample of 948 younger and older adults, we investigated whether a common Val66Met missense polymorphism (rs6265) in the BDNF gene affects the serial position curve—a fundamental phenomenon of associative memory identified by Hermann Ebbinghaus more than a century ago. We found a BDNF polymorphism effect for backward recall in older adults only, with Met-allele carriers (i.e., individuals with reduced BDNF signaling) recalling fewer items than Val homozygotes. This effect was specific to the primacy and middle portions of the serial position curve, where intralist interference and associative demands are especially high. The poorer performance of older Met-allele carriers reflected transposition errors, whereas no genetic effect was found for omissions. These findings indicate that effects of the BDNF polymorphism on episodic memory are most likely to be observed when the associative and executive demands are high. Furthermore, the findings are in line with the hypothesis that the magnitude of genetic effects on cognition is greater when brain resources are reduced, as is the case in old age.
    Type of Medium: Online Resource
    ISSN: 0898-929X , 1530-8898
    URL: Article
    DOI: 10.1162/jocn.2009.21374
    Language: English
    Publisher: MIT Press
    Publication Date: 2010
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  • 6
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    Online Resource
    Normal Aging Delays and Compromises Early Multifocal Visual Attention during Object Tracking
    MIT Press ; 2013
    In:  Journal of Cognitive Neuroscience Vol. 25, No. 2 ( 2013-02-01), p. 188-202
    Details
    In: Journal of Cognitive Neuroscience, MIT Press, Vol. 25, No. 2 ( 2013-02-01), p. 188-202
    Abstract: Declines in selective attention are one of the sources contributing to age-related impairments in a broad range of cognitive functions. Most previous research on mechanisms underlying older adults' selection deficits has studied the deployment of visual attention to static objects and features. Here we investigate neural correlates of age-related differences in spatial attention to multiple objects as they move. We used a multiple object tracking task, in which younger and older adults were asked to keep track of moving target objects that moved randomly in the visual field among irrelevant distractor objects. By recording the brain's electrophysiological responses during the tracking period, we were able to delineate neural processing for targets and distractors at early stages of visual processing (∼100–300 msec). Older adults showed less selective attentional modulation in the early phase of the visual P1 component (100–125 msec) than younger adults, indicating that early selection is compromised in old age. However, with a 25-msec delay relative to younger adults, older adults showed distinct processing of targets (125–150 msec), that is, a delayed yet intact attentional modulation. The magnitude of this delayed attentional modulation was related to tracking performance in older adults. The amplitude of the N1 component (175–210 msec) was smaller in older adults than in younger adults, and the target amplification effect of this component was also smaller in older relative to younger adults. Overall, these results indicate that normal aging affects the efficiency and timing of early visual processing during multiple object tracking.
    Type of Medium: Online Resource
    ISSN: 0898-929X , 1530-8898
    URL: Article
    DOI: 10.1162/jocn_a_00303
    Language: English
    Publisher: MIT Press
    Publication Date: 2013
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  • 7
    Online Resource
    Online Resource
    A Scaffold for Efficiency in the Human Brain
    Society for Neuroscience ; 2013
    In:  The Journal of Neuroscience Vol. 33, No. 43 ( 2013-10-23), p. 17150-17159
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 33, No. 43 ( 2013-10-23), p. 17150-17159
    Abstract: The comprehensive relations between healthy adult human brain white matter (WM) microstructure and gray matter (GM) function, and their joint relations to cognitive performance, remain poorly understood. We investigated these associations in 27 younger and 28 older healthy adults by linking diffusion tensor imaging (DTI) with functional magnetic resonance imaging (fMRI) data collected during an n-back working memory task. We present a novel application of multivariate Partial Least Squares (PLS) analysis that permitted the simultaneous modeling of relations between WM integrity values from all major WM tracts and patterns of condition-related BOLD signal across all GM regions. Our results indicate that greater microstructural integrity of the major WM tracts was negatively related to condition-related blood oxygenation level-dependent (BOLD) signal in task-positive GM regions. This negative relationship suggests that better quality of structural connections allows for more efficient use of task-related GM processing resources. Individuals with more intact WM further showed greater BOLD signal increases in typical “task-negative” regions during fixation, and notably exhibited a balanced magnitude of BOLD response across task-positive and -negative states. Structure—function relations also predicted task performance, including accuracy and speed of responding. Finally, structure–function–behavior relations reflected individual differences over and above chronological age. Our findings provide evidence for the role of WM microstructure as a scaffold for the context-relevant utilization of GM regions.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.1426-13.2013
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2013
    detail.hit.zdb_id: 1475274-8
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  • 8
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    Amphetamine modulates brain signal variability and working memory in younger and older adults
    Proceedings of the National Academy of Sciences ; 2015
    In:  Proceedings of the National Academy of Sciences Vol. 112, No. 24 ( 2015-06-16), p. 7593-7598
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 112, No. 24 ( 2015-06-16), p. 7593-7598
    Abstract: Better-performing younger adults typically express greater brain signal variability relative to older, poorer performers. Mechanisms for age and performance-graded differences in brain dynamics have, however, not yet been uncovered. Given the age-related decline of the dopamine (DA) system in normal cognitive aging, DA neuromodulation is one plausible mechanism. Hence, agents that boost systemic DA [such as d -amphetamine (AMPH)] may help to restore deficient signal variability levels. Furthermore, despite the standard practice of counterbalancing drug session order (AMPH first vs. placebo first), it remains understudied how AMPH may interact with practice effects, possibly influencing whether DA up-regulation is functional. We examined the effects of AMPH on functional-MRI–based blood oxygen level-dependent (BOLD) signal variability (SD BOLD ) in younger and older adults during a working memory task (letter n -back). Older adults expressed lower brain signal variability at placebo, but met or exceeded young adult SD BOLD levels in the presence of AMPH. Drug session order greatly moderated change–change relations between AMPH-driven SD BOLD and reaction time means (RT mean ) and SDs (RT SD ). Older adults who received AMPH in the first session tended to improve in RT mean and RT SD when SD BOLD was boosted on AMPH, whereas younger and older adults who received AMPH in the second session showed either a performance improvement when SD BOLD decreased (for RT mean ) or no effect at all (for RT SD ). The present findings support the hypothesis that age differences in brain signal variability reflect aging-induced changes in dopaminergic neuromodulation. The observed interactions among AMPH, age, and session order highlight the state- and practice-dependent neurochemical basis of human brain dynamics.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1504090112
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2015
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  • 9
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    Online Resource
    Genetic variation in dopaminergic neuromodulation influences the ability to rapidly and flexibly adapt decisions
    Proceedings of the National Academy of Sciences ; 2009
    In:  Proceedings of the National Academy of Sciences Vol. 106, No. 42 ( 2009-10-20), p. 17951-17956
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 106, No. 42 ( 2009-10-20), p. 17951-17956
    Abstract: The ability to rapidly and flexibly adapt decisions to available rewards is crucial for survival in dynamic environments. Reward-based decisions are guided by reward expectations that are updated based on prediction errors, and processing of these errors involves dopaminergic neuromodulation in the striatum. To test the hypothesis that the COMT gene Val 158 Met polymorphism leads to interindividual differences in reward-based learning, we used the neuromodulatory role of dopamine in signaling prediction errors. We show a behavioral advantage for the phylogenetically ancestral Val/Val genotype in an instrumental reversal learning task that requires rapid and flexible adaptation of decisions to changing reward contingencies in a dynamic environment. Implementing a reinforcement learning model with a dynamic learning rate to estimate prediction error and learning rate for each trial, we discovered that a higher and more flexible learning rate underlies the advantage of the Val/Val genotype. Model-based fMRI analysis revealed that greater and more differentiated striatal fMRI responses to prediction errors reflect this advantage on the neurobiological level. Learning rate-dependent changes in effective connectivity between the striatum and prefrontal cortex were greater in the Val/Val than Met/Met genotype, suggesting that the advantage results from a downstream effect of the prefrontal cortex that is presumably mediated by differences in dopamine metabolism. These results show a critical role of dopamine in processing the weight a particular prediction error has on the expectation updating for the next decision, thereby providing important insights into neurobiological mechanisms underlying the ability to rapidly and flexibly adapt decisions to changing reward contingencies.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0905191106
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2009
    detail.hit.zdb_id: 209104-5
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  • 10
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    Aging and Neuroeconomics: Insights from Research on Neuromodulation of Reward-based Decision Making
    Walter de Gruyter GmbH ; 2007
    In:  Analyse & Kritik Vol. 29, No. 1 ( 2007-5-1), p. 97-111
    Details
    In: Analyse & Kritik, Walter de Gruyter GmbH, Vol. 29, No. 1 ( 2007-5-1), p. 97-111
    Abstract: ‘Neuroeconomics’ can be broadly defined as the research of how the brain interacts with the environment to make decisions that are functional given individual and contextual constraints. Deciphering such brain-environment transactions requires mechanistic understandings of the neurobiological processes that implement value-dependent decision making. To this end, a common empirical approach is to investigate neural mechanisms of reward-based decision making. Flexible updating of choices and associated expected outcomes in ways that are adaptive for a given task (or a given set of tasks) at hand relies on dynamic neurochemical tuning of the brain’s functional circuitries involved in the representation of tasks, goals and reward prediction. Empirical evidence as well as computational theories indicate that various neurotransmitter systems (e.g., dopamine, norepinephrine, and serotonin) play important roles in reward-based decision making. In light of the apparent aging-related decline in various aspects of the dopaminergic system as well as the effects of neuromodulation on reward-related processes, this article focuses selectively on the literature that highlights the triadic relations between dopaminergic modulation, reward-based decision making, and aging. Directions for future research on aging and neuroeconomoics are discussed.
    Type of Medium: Online Resource
    ISSN: 2365-9858 , 0171-5860
    URL: Article
    DOI: 10.1515/auk-2007-0107
    RVK:
    MN 1000
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2007
    detail.hit.zdb_id: 2211788-X
    detail.hit.zdb_id: 558867-4
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