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  • 1. de Frias, Cindy M
    et al.
    Annerbrink, Kristina
    Westberg, Lars
    Eriksson, Elias
    Adolfsson, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Psykiatri.
    Nilsson, Lars-Göran
    Catechol O-methyltransferase Val(158)Met polymorphism is associated with cognitive performance in nondemented adults2005Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 17, nr 7, s. 1018-1025Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The catechol O-methyltransferase ( COMT) gene is essential in the metabolic degradation of dopamine in the prefrontal cortex. In the present study, we examined the effect of a Val 158 Met polymorphism in the COMT gene on individual differences and changes in cognition ( executive functions and visuospatial ability) in adulthood and old age. The participants were 292 nondemented men ( initially aged 35-85 years) from a random sample of the population (i.e., the Betula study) tested at two occasions with a 5-year interval. Confirmatory factor analyses were used to test the underlying structure of three indicators of executive functions ( verbal fluency, working memory, and Tower of Hanoi). Associations between COMT, age, executive functioning, and visuospatial ( block design) tasks were examined using repeated-measures analyses of variance. Carriers of the Val allele ( with higher enzyme activity) compared with carriers of the Met/Met genotype ( with low enzyme activity) performed worse on executive functioning and visuospatial tasks. Individuals with the Val/Val genotype declined in executive functioning over the 5-year period, whereas carriers of the Met allele remained stable in performance. An Age x COMT interaction for visuospatial ability located the effect for middle-aged men only. This COMT polymorphism is a plausible candidate gene for executive functioning and fluid intelligence in nondemented middle-aged and older adults.

  • 2.
    de Frias, Cindy M
    et al.
    Stockholm University.
    Marklund, Petter
    Stockholm University, Stockholm Brain Institute.
    Eriksson, Elias
    Göteborg University.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Öman, Lena
    Umeå universitet.
    Annerbrink, Kristina
    Göteborg University.
    Bäckman, Lars
    Karolinska Institute.
    Nilsson, Lars-Göran
    Stockholm University.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Influence of COMT gene polymorphism on fMRI-assessed sustained and transient activity during a working memory task.2010Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 22, nr 7, s. 1614-1622Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The catechol O-methyltransferase (COMT) gene--encoding an enzyme that is essential for the degradation of dopamine (DA) in prefrontal cortex (PFC)--contains a single nucleotide polymorphism (val/met) important for cognition. According to the tonic-phasic hypothesis, individuals carrying the low-enzyme-activity allele (met) are characterized by enhanced tonic DA activity in PFC, promoting sustained cognitive representations in working memory. Val carriers have reduced tonic but enhanced phasic dopaminergic activity in subcortical regions, enhancing cognitive flexibility. We tested the tonic-phasic DA hypothesis by dissociating sustained and transient brain activity during performance on a 2-back working memory test using mixed blocked/event-related functional magnetic resonance imaging. Participants were men recruited from a random sample of the population (the Betula study) and consisted of 11 met/met and 11 val/val carriers aged 50 to 65 years, matched on age, education, and cognitive performance. There were no differences in 2-back performance between genotype groups. Met carriers displayed a greater transient medial temporal lobe response in the updating phase of working memory, whereas val carriers showed a greater sustained PFC activation in the maintenance phase. These results support the tonic-phasic theory of DA function in elucidating the specific phenotypic influence of the COMT val(158)met polymorphism on different components of working memory.

  • 3.
    Eriksson, Johan
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Bergström, Fredrik
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Unconscious working memory engages the prefrontal cortex2013Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 25, nr Suppl., s. S74-S74Artikkel i tidsskrift (Annet vitenskapelig)
  • 4.
    Eriksson, Johan
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Item-specific training reduces prefrontal cortical involvement in perceptual awareness2008Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 20, nr 10, s. 1777-1787Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previous studies on the neural correlates of perceptual awareness implicate sensory-specific regions and higher cortical regions such as the prefrontal cortex (PFC) in this process. The specific role of PFC regions is, however, unknown. PFC activity could be bottom-up driven, integrating signals from sensory regions. Alternatively, PFC regions could serve more active top-down processes that help to define the content of consciousness. To compare these alternative views of PFC function, we used functional magnetic resonance imaging and measured brain activity specifically related to conscious perception of items that varied in ease of identification (by being presented 0, 12, or 60 times previously). A bottom-up account predicts that PFC activity would be largely insensitive to stimulus difficulty, whereas a top-down account predicts reduced PFC activity as identification becomes easier. The results supported the latter prediction by showing reduced activity for previously presented compared to novel items in the PFC and several other regions. This was further confirmed by a functional connectivity analysis showing that the interaction between frontal and visual sensory regions declined as a function of ease of identification. Given the attribution of top-down processing to PFC regions in combination with the marked decline in PFC activity for easy items, these findings challenge the prevailing notion that the PFC is necessary for consciousness.

  • 5.
    Karalija, Nina
    et al.
    Umeå universitet.
    Papenberg, Goran
    Wåhlin, Anders
    Umeå universitet.
    Johansson, Jarkko
    Umeå universitet.
    Andersson, Micael
    Umeå universitet.
    Axelsson, Jan
    Umeå universitet.
    Riklund, Katrine
    Umeå universitet.
    Lövdén, Martin
    Lindenberger, Ulman
    Bäckman, Lars
    Nyberg, Lars
    Umeå universitet.
    C957T-mediated Variation in Ligand Affinity Affects the Association between C-11-raclopride Binding Potential and Cognition2019Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 31, nr 2, s. 314-325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dopamine (DA) system plays an important role in cognition. Accordingly, normal variation in DA genes has been found to predict individual differences in cognitive performance. However, little is known of the impact of genetic differences on the link between empirical indicators of the DA system and cognition in humans. The present work used PET with C-11-raclopride to assess DA D2-receptor binding potential (BP) and links to episodic memory, working memory, and perceptual speed in 179 healthy adults aged 64-68 years. Previously, the T-allele of a DA D2-receptor single-nucleotide polymorphism, C957T, was associated with increased apparent affinity of C-11-raclopride, giving rise to higher BP values despite similar receptor density values between allelic groups. Consequently, we hypothesized that C-11-raclopride BP measures inflated by affinity rather than D2-receptor density in T-allele carriers would not be predictive of DA integrity and therefore prevent finding an association between C-11-raclopride BP and cognitive performance. In accordance with previous findings, we show that C-11-raclopride BP was increased in T-homozygotes. Importantly, C-11-raclopride BP was only associated with cognitive performance in groups with low or average ligand affinity (C-allele carriers of C957T, n = 124), but not in the high-affinity group (T-homozygotes, n = 55). The strongest C-11-raclopride BP-cognition associations and the highest level of performance were found in C-homozygotes. These findings show that genetic differences modulate the link between BP and cognition and thus have important implications for the interpretation of DA assessments with PET and C-11-raclopride in multiple disciplines ranging from cognitive neuroscience to psychiatry and neurology.

  • 6.
    Karlsson, Linnea
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Wiklund-Hornqvist, Carola
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Eriksson, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Jonsson, Bert
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Retrieval practice is characterized by reduced fronto-striatal activity2013Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 25, nr Suppl., s. S82-S83Artikkel i tidsskrift (Annet vitenskapelig)
  • 7.
    Kauppi, Karolina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Nilsson, Lars-Göran
    Adolfsson, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Psykiatri.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Combined gene effects on hippocampal mnemonic processing: a large-scale imaging-genetics study of APOE, BDNF, KIBRA, and CLSTN22013Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 25, nr Suppl., s. S140-S141Artikkel i tidsskrift (Annet vitenskapelig)
  • 8.
    Kompus, Kristiina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Eichele, Tom
    University of Bergen.
    Hugdahl, Kenneth
    University of Bergen.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Multimodal imaging of incidental retrieval: the low route to memory2011Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 23, nr 4, s. 947-960Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Memories of past episodes frequently come to mind incidentally, without directed search. It has remained unclear how incidental retrieval processes are initiated in the brain. Here we used fMRI and ERP recordings to find brain activity that specifically correlates with incidental retrieval, as compared to intentional retrieval. Intentional retrieval was associated with increased activation in the dorsolateral prefrontal cortex. By contrast, incidental retrieval was associated with a reduced fMRI signal in posterior brain regions, including extrastriate and parahippocampal cortex, and a modulation of a posterior ERP component 170 ms after the onset of visual retrieval cues. Successful retrieval under both intentional and incidental conditions was associated with increased activation in hippocampus, precuneus and ventrolateral prefrontal cortex, as well as increased amplitude of the P600 ERP component. These results demonstrate how early bottom-up signals from the posterior cortex can lead to reactivation of episodic memories in the absence of strategic retrieval attempts.

  • 9. Li, Shu-Chen
    et al.
    Chicherio, Christian
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    von Oertzen, Timo
    Nagel, Irene E
    Sander, Thomas
    Heekeren, Hauke R
    Lindenberger, Ulman
    Bäckman, Lars
    Ebbinghaus Revisited: Influences of the BDNF Val66Met Polymorphism on Backward Serial Recall Are Modulated by Human Aging.2010Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 22, nr 10, s. 2164-2173Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 10. MacDonald, Stuart W S
    et al.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Sandblom, Johan
    Fischer, Håkan
    Bäckman, Lars
    Increased response-time variability is associated with reduced inferior parietal activation during episodic recognition in aging.2008Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 20, nr 5, s. 779-786Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Intraindividual variability (IIV) in cognitive performance shares systematic associations with aging-related processes, brain injury, and neurodegenerative pathology. However, little research has examined the neural underpinnings of IIV, with no studies investigating brain correlates of IIV in relation to retrieval success. Using functional magnetic resonance imaging, we examined links between IIV, recognition memory performance, and blood oxygenation level dependent activations. Nineteen older adults (70-79 years) were presented with 80 words at encoding, with brain scans and response latencies obtained during subsequent recognition. An index of IIV, the intraindividual standard deviation (ISD), was computed across successful latency trials. Decreasing ISDs were systematically associated with better recognition, faster latencies, and increased activation in the inferior parietal cortex (BA 40). Demonstrated links between less behavioral variability and parietal activations are consistent with the known importance of the parietal cortex for retrieval success. In support of extant findings and theory from neuroscience, neuropsychology, and cognitive aging, the present results suggest that behavioral IIV represents a proxy for neural integrity.

  • 11.
    Nagel, Irene E
    et al.
    Max Planck Institute for Human Development, Berlin, Freie Universität Berlin.
    Preuschhof, Claudia
    Max Planck Institute for Human Development, Berlin, Freie Universität Berlin.
    Li, Shu-Chen
    Max Planck Institute for Human Development, Berlin.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Bäckman, Lars
    Max Planck Institute for Human Development, Berlin, Karolinska Institute.
    Lindenberger, Ulman
    Max Planck Institute for Human Development, Berlin.
    Heekeren, Hauke R
    x Planck Institute for Human Development, Berlin, Freie Universität Berlin.
    Load Modulation of BOLD Response and Connectivity Predicts Working Memory Performance in Younger and Older Adults.2011Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 23, nr 8, s. 2030-2045Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 12.
    Nordmark, Per F.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Pruszynski, J. Andrew
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Johansson, Roland S.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    BOLD Responses to Tactile Stimuli in Visual and Auditory Cortex Depend on the Frequency Content of Stimulation2012Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 24, nr 10, s. 2120-2134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although some brain areas preferentially process information from a particular sensory modality, these areas can also respond to other modalities. Here we used fMRI to show that such responsiveness to tactile stimuli depends on the temporal frequency of stimulation. Participants performed a tactile threshold-tracking task where the tip of either their left or right middle finger was stimulated at 3, 20, or 100 Hz. Whole-brain analysis revealed an effect of stimulus frequency in two regions: the auditory cortex and the visual cortex. The BOLD response in the auditory cortex was stronger during stimulation at hearable frequencies (20 and 100 Hz) whereas the response in the visual cortex was suppressed at infrasonic frequencies (3 Hz). Regardless of which hand was stimulated, the frequency-dependent effects were lateralized to the left auditory cortex and the right visual cortex. Furthermore, the frequency-dependent effects in both areas were abolished when the participants performed a visual task while receiving identical tactile stimulation as in the tactile threshold-tracking task. We interpret these findings in the context of the metamodal theory of brain function, which posits that brain areas contribute to sensory processing by performing specific computations regardless of input modality.

  • 13.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Andersson, Micael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Kauppi, Karolina
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Lundquist, Anders
    Umeå universitet, Samhällsvetenskapliga fakulteten, Handelshögskolan vid Umeå universitet. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Persson, Jonas
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Stockholm Brain Institute, Karolinska Institute, Stockholm, Sweden.
    Pudas, Sara
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Karolinska Institute, Stockholm, Sweden.
    Nilsson, Lars-Göran
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Stockholm University, Stockholm Brain Institute.
    Age-related and genetic modulation of frontal cortex efficiency2014Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 26, nr 4, s. 746-754Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dorsolateral pFC (DLPFC) is a key region for working memory. It has been proposed that the DLPFC is dynamically recruited depending on task demands. By this view, high DLPFC recruitment for low-demanding tasks along with weak DLPFC upregulation at higher task demands reflects low efficiency. Here, the fMRI BOLD signal during working memory maintenance and manipulation was examined in relation to aging and catechol-O-methyltransferase (COMT) Val(158)Met status in a large representative sample (n = 287). The efficiency hypothesis predicts a weaker DLPFC response during manipulation, along with a stronger response during maintenance for older adults and COMT Val carriers compared with younger adults and COMT Met carriers. Consistent with the hypothesis, younger adults and met carriers showed maximal DLPFC BOLD response during manipulation, whereas older adults and val carriers displayed elevated DLPFC responses during the less demanding maintenance condition. The observed inverted relations support a link between dopamine and DLPFC efficiency.

  • 14. Papenberg, Goran
    et al.
    Karalija, Nina
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Salami, Alireza
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Andersson, Micael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Axelsson, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Riklund, Katrine
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Lindenberger, Ulman
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Bäckman, Lars
    The Influence of Hippocampal Dopamine D2 Receptors on Episodic Memory Is Modulated by BDNF and KIBRA Polymorphisms2019Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 31, nr 9, s. 1422-1429Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Episodic memory is a polygenic trait influenced by different molecular mechanisms. We used PET and a candidate gene approach to investigate how individual differences at the molecular level translate into between-person differences in episodic memory performance of elderly persons. Specifically, we examined the interactive effects between hippocampal dopamine D2 receptor (D2DR) availability and candidate genes relevant for hippocampus-related memory functioning. We show that the positive effects of high D2DR availability in the hippocampus on episodic memory are confined to carriers of advantageous genotypes of the brain-derived neurotrophic factor (BDNF, rs6265) and the kidney and brain expressed protein (KIBRA, rs17070145) polymorphisms. By contrast, these polymorphisms did not modulate the positive relationship between caudate D2DR availability and episodic memory.

  • 15.
    Persson, Jonas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Stockholm Univ, S-11330 Stockholm, Sweden; Karolinska Inst, S-11330 Stockholm, Sweden .
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Reuter-Lorenz, Patricia A
    Imaging fatigue of interference control reveals the neural basis of executive resource depletion2013Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 25, nr 3, s. 338-351Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Executive control coordinates, prioritizes, and selects task-relevant representations under conditions of conflict. Behavioral evidence has documented that executive resources are separable, finite, and can be temporarily depleted; however, the neural basis for such resource limits are largely unknown. Here, we investigate the neural correlates underlying the fatigue or depletion of interference control, an executive process hypothesized to mediate competition among candidate memory representations. Using a pre/post continuous acquisition fMRI design, we demonstrate that, compared with a nondepletion control group, the depletion group showed a fatigue-induced performance deficit that was specific to interference control and accompanied by a left-to-right shift in the network of active regions. Specifically, we observed decreased BOLD signal in the left inferior frontal gyrus (IFG), striatum, and the cerebellum, along with a corresponding increase in right hemisphere regions including the IFG, insular, and temporal cortex. Depletion-related changes in activation magnitude correlated with behavioral changes, suggesting that decreased recruitment of task-relevant regions, including left IFG, contributes to impaired interference control. These results provide new evidence about the brain dynamics of "process-specific" fatigue and suggest that depletion may pose a significant limitation on the cognitive and neural resources available for executive control.

  • 16.
    Sundström, Anna
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för befolkningsstudier (CBS).
    Nilsson, Lars-Göran
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Cognitive performance before and after mild head injury.2002Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. Suppl, nr B77, s. 60-Artikkel i tidsskrift (Fagfellevurdert)
  • 17.
    Vestergren, Peter
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Test-potentiated encoding of paired associates as revealed by functional magnetic resonance imaging2013Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 25, nr Suppl., s. S113-S114Artikkel i tidsskrift (Annet vitenskapelig)
  • 18.
    Wiklund-Hörnqvist, Carola
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Karlsson, Linnea
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Eriksson, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Andersson, Micael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Jonsson, Bert
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Activity in left temporal-parietal regions characterizes long-term retention after repeated testing2013Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 25, nr Suppl., s. S114-S114Artikkel i tidsskrift (Annet vitenskapelig)
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