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  • 301.
    Jonasson, Lars S.
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Axelsson, Jan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Kramer, Arthur F.
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Boraxbekk, Carl-Johan
    Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital, Hvidovre, Denmark.
    Higher striatal D2-receptor availability in aerobically fit older adults but non-selective intervention effects after aerobic versus resistance training2019In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 202, article id 116044Article in journal (Refereed)
    Abstract [en]

    There is much evidence that dopamine is vital for cognitive functioning in aging. Here we tested the hypothesis that aerobic exercise and fitness influence dopaminergic neurotransmission in the striatum, and in turn performance on offline working-memory updating tasks. Dopaminergic neurotransmission was measured by positron emission tomography (PET) and the non-displacable binding potential (BPND) of [11C]raclopride, i.e. dopamine (DA) D2-receptor (D2R) availability. Fifty-four sedentary older adults underwent a six-months exercise intervention, performing either aerobic exercise or stretching, toning, and resistance active control training. At baseline, higher aerobic fitness levels (VO2peak) were associated with higher BPND in the striatum, providing evidence of a link between an objective measure of aerobic fitness and D2R in older adults. BPND decreased substantially over the intervention in both groups but the intervention effects were non-selective with respect to exercise group. The decrease was several times larger than any previously estimated annual decline in D2R, potentially due to increased endogenous DA. Working-memory was unrelated to D2R both at baseline and following the intervention. To conclude, we provide partial evidence for a link between physical exercise and DA. Utilizing a PET protocol able to disentangle both D2R and DA levels could shed further light on whether, and how, aerobic exercise impacts the dopaminergic system in older adults.

  • 302.
    Jones, Iwan
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Hägglund, Anna-Carin
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Carlsson, Leif
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Reduced mTORC1-signalling in retinal progenitor cells leads to visual pathway dysfunction2019In: Biology Open, ISSN 2046-6390, Vol. 8, no 8, article id bio044370Article in journal (Refereed)
    Abstract [en]

    Development of the vertebrate central nervous system involves the co-ordinated differentiation of progenitor cells and the establishment of functional neural networks. This neurogenic process is driven by both intracellular and extracellular cues that converge on the mammalian target of rapamycin complex 1 (mTORC1). Here we demonstrate that mTORC1-signalling mediates multi-faceted roles during central nervous system development using the mouse retina as a model system. Downregulation of mTORC1-signalling in retinal progenitor cells by conditional ablation of Rptor leads to proliferation deficits and an over-production of retinal ganglion cells during embryonic development. In contrast, reduced mTORC1-signalling in postnatal animals leads to temporal deviations in programmed cell death and the consequent production of asymmetric retinal ganglion cell mosaics and associated loss of axonal termination topographies in the dorsal lateral geniculate nucleus of adult mice. In combination these developmental defects induce visually mediated behavioural deficits. These collective observations demonstrate that mTORC1-signalling mediates critical roles during visual pathway development and function.

  • 303.
    Jones, Iwan
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Novikova, Liudmila N.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Novikov, Lev N.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Renardy, Monika
    Ullrich, Andreas
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Carlsson, Leif
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Regenerative effects of human embryonic stem cell-derived neural crest cells for treatment of peripheral nerve injury2018In: Journal of Tissue Engineering and Regenerative Medicine, ISSN 1932-6254, E-ISSN 1932-7005, Vol. 12, no 4, p. E2099-E2109Article in journal (Refereed)
    Abstract [en]

    Surgical intervention is the current gold standard treatment following peripheral nerve injury. However, this approach has limitations, and full recovery of both motor and sensory modalities often remains incomplete. The development of artificial nerve grafts that either complement or replace current surgical procedures is therefore of paramount importance. An essential component of artificial grafts is biodegradable conduits and transplanted cells that provide trophic support during the regenerative process. Neural crest cells are promising support cell candidates because they are the parent population to many peripheral nervous system lineages. In this study, neural crest cells were differentiated from human embryonic stem cells. The differentiated cells exhibited typical stellate morphology and protein expression signatures that were comparable with native neural crest. Conditioned media harvested from the differentiated cells contained a range of biologically active trophic factors and was able to stimulate in vitro neurite outgrowth. Differentiated neural crest cells were seeded into a biodegradable nerve conduit, and their regeneration potential was assessed in a rat sciatic nerve injury model. A robust regeneration front was observed across the entire width of the conduit seeded with the differentiated neural crest cells. Moreover, the up-regulation of several regeneration-related genes was observed within the dorsal root ganglion and spinal cord segments harvested from transplanted animals. Our results demonstrate that the differentiated neural crest cells are biologically active and provide trophic support to stimulate peripheral nerve regeneration. Differentiated neural crest cells are therefore promising supporting cell candidates to aid in peripheral nerve repair.

  • 304.
    Jones, Iwan
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Yelhekar, Tushar D.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Wiberg, Rebecca
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Johansson, Staffan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Carlsson, Leif
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Development and validation of an in vitro model system to study peripheral sensory neuron development and injury2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 15961Article in journal (Refereed)
    Abstract [en]

    The ability to discriminate between diverse types of sensation is mediated by heterogeneous populations of peripheral sensory neurons. Human peripheral sensory neurons are inaccessible for research and efforts to study their development and disease have been hampered by the availability of relevant model systems. The in vitro differentiation of peripheral sensory neurons from human embryonic stem cells therefore provides an attractive alternative since an unlimited source of biological material can be generated for studies that specifically address development and injury. The work presented in this study describes the derivation of peripheral sensory neurons from human embryonic stem cells using small molecule inhibitors. The differentiated neurons express canonical- and modality-specific peripheral sensory neuron markers with subsets exhibiting functional properties of human nociceptive neurons that include tetrodotoxin-resistant sodium currents and repetitive action potentials. Moreover, the derived cells associate with human donor Schwann cells and can be used as a model system to investigate the molecular mechanisms underlying neuronal death following peripheral nerve injury. The quick and efficient derivation of genetically diverse peripheral sensory neurons from human embryonic stem cells offers unlimited access to these specialised cell types and provides an invaluable in vitro model system for future studies.

  • 305. Jons, D
    et al.
    Sundström, Peter
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Andersen, O
    Targeting Epstein-Barr virus infection as an intervention against multiple sclerosis2015In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 131, no 2, p. 69-79Article, review/survey (Refereed)
    Abstract [en]

    We here review contemporary data on genetic and environmental risk factors, particularly Epstein-Barr virus infection, for multiple sclerosis. There is an important immunogenetic etiological factor for multiple sclerosis. However, a general assumption is that immune defense genes are activated by the environment, basically by infections. We contend that the relationship between infectious mononucleosis and multiple sclerosis cannot be completely explained by genetics and inverse causality. Epstein-Barr infection as indicated by positive serology is an obligatory precondition for multiple sclerosis, which is a stronger attribute than a risk factor only. Data on events in the early pathogenesis of multiple sclerosis are cumulating from bio-banks with presymptomatic specimens, but there is only little information from the critical age when Epstein-Barr infection including infectious mononucleosis is acquired, nor on the detailed immunological consequences of this infection in individuals with and without multiple sclerosis. We discuss how focused bio-banking may elaborate a rationale for the development of treatment or vaccination against Epstein-Barr virus infection. A cohort in which intervention against Epstein-Barr infections was performed should be the object of neurological follow-up.

  • 306.
    Jonsson, Joakim
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Detecting Cardiac Pulsatility and Respiration using Multiband fMRI2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Purpose: Arterial stiffening poses an increased risk of cerebrovascular diseases, cognitive impairments, and even dementia as cardiac pulsations reach further into the brain causing white matter hyperintensities and microbleeds. Therefore it is of interest to obtain methods to estimate and map cardiac related pulsatility in the brain. Improvements of functional magnetic resonance imaging (fMRI) sequences is potentially allowing detection of rapid physiological processes in the echo-planar imaging (EPI) signal in the brainthrough a higher sampling rate. Specifically in this thesis, estimation and localization of cardiac pulsation and respiration is conducted through analysis of resting state data obtained with a multiband EPI sequence that permits whole brain imaging at a shorter repetition time (TR) than conventional EPI. The origin of these physiological signals are likely a mixture of inflow and compartment volume shifts during the cardiac- and respiratory cycles. As the amount of physiologically related signal in the multiband sequence used at the Biomedical Engineering Dept. R&D, Umeå University Hospital is unknown, the aim of this project is to find and map cardiac pulsatility and respiration for future research.

    Methods: Multiband fMRI data from 8 subjects was used, collected in a 3 Tesla scanner using a 32-channel head coil. The physiological signals were estimated through an algorithm that was developed to down-sample and temporally shift copies of simultaneous recordings of pulse and respiration. These signals were obtained using the scanner’s built-in pulse oximeter and a respiration belt. The shifted copies were voxel-wise, and slice by slice, correlated to the fMRI data using Pearson correlation. The time shift yielding maximum mean correlation within the brain was, for each slice, used to create statistical maps for significant voxels to show the localization and magnitude of correlation for cardiac pulsation andrespiration.

    Results: Many voxels around and nearby larger vessels and ventricles were highly correlated with the down-sampled, time shifted signals of the cardiac pulsation for all subjects. The cardiac pulsation maps resembled cerebral vasculature and were mostly localized around the Circle of Willis, brainstem, and the ventricles. Respiration signal was also highly correlated, and spatially located at the sides of the brain although mostly concentrated at the parietal- and occipital lobes.

    Conclusion: The results demonstrated that many voxels in the brain were highly correlated with cardiac pulsation and respiration using multiband EPI, and the statistical maps revealed distinct patterns for both of the physiological signals. This method and results for mapping cardiac related pulsatility, and respiration could be used for future research in order to better understand cerebral diseases and impairments, and alsoto improve fMRI filtering.

    Keywords: Arterial stiffness, Functional magnetic resonance imaging, Resting state, Multiband, CardiacPulsation, Respiration, Correlation analysis

  • 307.
    Josefsson, Maria
    et al.
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    de Luna, Xavier
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    Daniels, Michael
    University of Texas at Austin.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Causal inference with longitudinal outcomes and non-ignorable drop-out: Estimating the effect of living alone on cognitive decline2016In: Journal of the Royal Statistic Society, Series C: Applied Statistics, ISSN 0035-9254, E-ISSN 1467-9876, Vol. 65, no 1, p. 131-144Article in journal (Refereed)
    Abstract [en]

    We develop a model to estimate the causal effect of living arrangement (living alone versus living with someone) on cognitive decline based on a 15-year prospective cohort study, where episodic memory function is measured every 5 years. One key feature of the model is the combination of propensity score matching to balance confounding variables between the two living arrangement groups—to reduce bias due to unbalanced covariates at baseline, with a pattern–mixture model for longitudinal data—to deal with non-ignorable dropout. A fully Bayesian approach allows us to convey the uncertainty in the estimation of the propensity score and subsequent matching in the inference of the causal effect of interest. The analysis conducted adds to previous studies in the literature concerning the protective effect of living with someone, by proposing a modelling approach treating living arrangement as an exposure.

  • 308.
    Josefsson, Maria
    et al.
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    Lundquist, Anders
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Imputation of missing longitudinal fMRI dataManuscript (preprint) (Other academic)
  • 309.
    Kaarniranta, Kai
    et al.
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Oksala, Niku
    Department of Surgery, Kuopio University Hospital, Kuopio, Finland.
    Karjalainen, Hannu
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Suuronen, Tiina
    Department of Neuroscience and Neurology, University of Kuopio, Kuopio, Finland.
    Sistonen, Lea
    Turku Centre for Biotechnology, University of Turku, Åbo Akademi University, Turku, Finland.
    Helminen, Heikki
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Salminen, Antero
    Department of Neurology, Kuopio University Hospital, Kuopio, Finland; Department of Neuroscience and Neurology, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Neuronal cells show regulatory differences in the hsp70 gene response.2002In: Brain Research. Molecular Brain Research, ISSN 0169-328X, E-ISSN 1872-6941, Vol. 101, no 1-2, p. 136-140, article id 12007842Article in journal (Refereed)
    Abstract [en]

    The synthesis of heat shock proteins (Hsps), encoded by heat shock genes, is increased in response to various stress stimuli. Hsps function as molecular chaperones, they dissociate cytotoxic stress-induced protein aggregates within cells and ensure improved survival. Induction of heat shock genes is mainly regulated at the transcriptional level. The stress responsive transcription factor, heat shock factor 1 (HSF1), is involved in the transcriptional induction of the heat shock genes. Our objective was to examine how hsp70 genes are regulated in different transformed and primary neurons upon exposure to elevated temperature. Our findings reveal that the Hsp70 response is regulated at the translational level in Neuro-2a neuroblastoma cells, while the IMR-32 neuroblastoma cells respond to stress by the classical HSF1-driven transcriptional regulatory mechanism. Primary rat hippocampal neurons show a lack of HSF1 and induction of the hsp70 gene. These observations suggest that neuronal cells display different hsp70 gene expression patterns which range from undetected response to transcriptional and posttranscriptional regulation during heat stress.

  • 310.
    Kaboodvand, Neda
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    Bäckman, Lars
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Salami, Alireza
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    The retrosplenial cortex: a memory gateway between the cortical default mode network and the medial temporal lobe2018In: Human Brain Mapping, ISSN 1065-9471, E-ISSN 1097-0193, Vol. 39, no 5, p. 2020-2034Article in journal (Refereed)
    Abstract [en]

    The default mode network (DMN) involves interacting cortical areas, including the posterior cingulate cortex (PCC) and the retrosplenial cortex (RSC), and subcortical areas, including the medial temporal lobe (MTL). The degree of functional connectivity (FC) within the DMN, particularly between MTL and medial-parietal subsystems, relates to episodic memory (EM) processes. However, past resting-state studies investigating the link between posterior DMN-MTL FC and EM performance yielded inconsistent results, possibly reflecting heterogeneity in the degree of connectivity between MTL and specific cortical DMN regions. Animal work suggests that RSC has structural connections to both cortical DMN regions and MTL, and may thus serve as an intermediate layer that facilitates information transfer between cortical and subcortical DMNs. We studied 180 healthy old adults (aged 64-68 years), who underwent comprehensive assessment of EM, along with resting-state fMRI. We found greater FC between MTL and RSC than between MTL and the other cortical DMN regions (e.g., PCC), with the only significant association with EM observed for MTL-RSC FC. Mediational analysis showed that MTL-cortical DMN connectivity increased with RSC as a mediator. Further analysis using a graph-theoretical approach on DMN nodes revealed the highest betweenness centrality for RSC, confirming that a high proportion of short paths among DMN regions pass through RSC. Importantly, the degree of RSC mediation was associated with EM performance, suggesting that individuals with greater mediation have an EM advantage. These findings suggest that RSC forms a critical gateway between MTL and cortical DMN to support EM in older adults.

  • 311.
    Kalliomäkia, Maija-Liisa
    et al.
    Uppsala University, Department for Surgical Sciences, Uppsala, Sweden. Department of Anaesthesia, Tampere University Hospital, Finland.
    Sandblom, Gabriel
    Karolinska Institutet, CLINTEC, Stockholm, Sweden.
    Mathias, Hallberg
    Department of Pharmaceutical Biosciences, Division of Biological Research on Drug Dependence, Uppsala University, Uppsala, Sweden.
    Grönbladh, Alfhild
    Department of Pharmaceutical Biosciences, Division of Biological Research on Drug Dependence, Uppsala University, Uppsala, Sweden.
    Gunnarsson, Ulf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Gordh, Torsten
    Uppsala University, Department for Surgical Sciences, Uppsala, Sweden. Pain Centre, Uppsala University Hospital, Uppsala, Sweden.
    Ginya, Harumi
    Division of IVD System Development, Precision System Science Co., Ltd., Chiba, Japan.
    Nyberg, Fred
    Department of Pharmaceutical Biosciences, Division of Biological Research on Drug Dependence, Uppsala University, Uppsala, Sweden.
    Genetic susceptibility to postherniotomy pain: the influence of polymorphisms in the Mu opioid receptor, TNF-α, GRIK3, GCH1, BDNF and CACNA2D2 genes2016In: Scandinavian Journal of Pain, ISSN 1877-8860, E-ISSN 1877-8879, Vol. 12, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Background and aims: Despite improvements in surgical technique, 5%–8% of patients undergoing herniorrhaphy still suffer from clinically relevant persistent postherniotomy pain. This is a problem at both individual and society levels. The aim of this study was to determine whether or not a single nucleotide polymorphism in a specific gene contributes to the development of persistent pain after surgery.

    Methods: One hundred individuals with persistent postherniotomy pain, along with 100 without pain matched for age, gender and type of surgery were identified in a previous cohort study on patients operated for groin hernia. All patients underwent a thorough sensory examination and blood samples were collected. DNA was extracted and analysed for single nucleotide polymorphism in the Mu opioid receptor, TNF-α, GRIK3, GCH1, BDNF and CACNA2D2 genes.

    Results: Patients with neuropathic pain were found to have a homozygous single nucleotide polymorph in the TNF-α gene significantly more often than pain-free patients (P = 0.036, one-tailed test).

    Conclusions: SNP in the TNF-α gene has a significant impact on the risk for developing PPSP.

    Implications: The result suggests the involvement of genetic variance in the development of pain and this requires further investigation.

  • 312.
    Kalpouzos, Grégoria
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Eriksson, Johan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Sjölie, Daniel
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Molin, Jonas
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Neurocognitive systems related to real-world prospective memory2010In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, no 10, p. e13304-Article in journal (Refereed)
    Abstract [en]

    Taken together, these findings show how brain systems complementary interact during real-world PM, and support a more complete model of PM that can be applied to naturalistic PM tasks and that we named PROspective MEmory DYnamic (PROMEDY) model because of its dynamics on both multi-phase iteration and the interactions of distinct neurocognitive networks.

  • 313. Kalpouzos, Grégoria
    et al.
    Fischer, Håkan
    Rieckmann, Anna
    Macdonald, Stuart W S
    Bäckman, Lars
    Impact of negative emotion on the neural correlates of long-term recognition in younger and older adults.2012In: Frontiers in integrative neuroscience, ISSN 1662-5145, Vol. 6, p. 74-Article in journal (Refereed)
    Abstract [en]

    Some studies have suggested that the memory advantage for negative emotional information over neutral information ("negativity effect") is reduced in aging. Besides the fact that most findings are based on immediate retrieval, the neural underpinnings of long-term emotional memory in aging have so far not been investigated. To address these issues, we assessed recognition of neutral and negative scenes after 1- and 3-week retention intervals in younger and older adults using functional magnetic resonance imaging. We further used an event-related design in order to disentangle successful, false, and true recognition. This study revealed four key findings: (1) increased retention interval induced an increased rate of false recognitions for negative scenes, canceling out the negativity effect (present for hit rates only) on discrimination in both younger and older adults; (2) in younger, but not older, adults, reduced activity of the medial temporal lobe was observed over time for neutral scenes, but not for negative scenes, where stable or increased activity was seen; (3) engagement of amygdala (AMG) was observed in older adults after a 3-week delay during successful recognition of negative scenes (hits vs. misses) in comparison with neutral scenes, which may indicate engagement of automatic processes, but engagement of ventrolateral prefrontal cortex was unrelated to AMG activity and performance; and (4) after 3 weeks, but not after 1 week, true recognition of negative scenes was characterized by more activity in left hippocampus and lateral occipito-temporal regions (hits vs. false alarms). As these regions are known to be related to consolidation mechanisms, the observed pattern may indicate the presence of delayed consolidation of true memories. Nonetheless, older adults' low performance in discrimination of negative scenes could reflect the fact that overall, after long delays of retention, they rely more on general information rather than on perceptual detail in making recognition judgments.

  • 314.
    Kalpouzos, Grégoria
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Persson, Jonas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Local brain atrophy accounts for functional activity differences in normal aging.2012In: Neurobiology of Aging, ISSN 0197-4580, E-ISSN 1558-1497, Vol. 33, no 3, p. 623.e1-623.e13Article in journal (Refereed)
    Abstract [en]

    Functional brain imaging studies of normal aging typically show age-related under- and overactivations during episodic memory tasks. Older individuals also undergo nonuniform gray matter volume (GMv) loss. Thus, age differences in functional brain activity could at least in part result from local atrophy. We conducted a series of voxel-based blood oxygen level-dependent (BOLD)-GMv analyses to highlight whether age-related under- and overrecruitment was accounted for by GMv changes. Occipital GMv loss accounted for underrecruitment at encoding. Efficiency reduction of sensory-perceptual mechanisms underpinned by these areas may partly be due to local atrophy. At retrieval, local GMv loss accounted for age-related overactivation of left dorsolateral prefrontal cortex, but not of left dorsomedial prefrontal cortex. Local atrophy also accounted for age-related overactivation in left lateral parietal cortex. Activity in these frontoparietal regions correlated with performance in the older group. Atrophy in the overrecruited regions was modest in comparison with other regions as shown by a between-group voxel-based morphometry comparison. Collectively, these findings link age-related structural differences to age-related functional under- as well as overrecruitment.

  • 315.
    Karalija, Amar
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Diagnostic and therapeutic strategies following spinal cord and brachial plexus injuries2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Traumatic injuries to the spinal cord and brachial plexus induce a significant inflammatory response in the nervous tissue with progressive degeneration of neurons and glial cells, and cause considerable physical and mental suffering in affected patients. This thesis investigates the effects of the antioxidants N-acetyl-cysteine (NAC) and acetyl-L- carnitine (ALC) on the survival of motoneurons in the brainstem and spinal cord, the expression of pro-apoptotic and pro-inflammatory cell markers, axonal sprouting and glial cell reactions after spinal hemisection in adult rats. In addition, a novel MRI protocol has been developed to analyse the extent of neuronal degeneration in the spinal cord. Rubrospinal neurons and tibial motoneurons were pre-labelled with the fluorescent tracer Fast Blue one week before cervical C3 or lumbar L5 spinal cord hemisection. The intrathecal treatment with the antioxidants NAC (2.4mg/day) or ALC (0.9 mg/day) was initiated immediately after injury using Alzet2002 osmotic mini pumps. Spinal cord injury increased the expression of apoptotic cell markers BAX and caspase 3, induced significant degeneration of rubrospinal neurons and spinal motoneurons with associated decrease in immunoreactivity for microtubule-associated protein-2 (MAP2) in dendritic branches, synaptophysin in presynaptic boutons and neurofilaments in nerve fibers. Immunostaining for the astroglial marker glial fibrillary acidic protein and microglial markers OX42 and ED1 was markedly increased. Treatment with NAC and ALC attenuated levels of BAX, caspase 3, OX42 and ED1 expression after 2 weeks postoperatively. After 4-8 weeks of continuous intratheca ltreatment, NAC and ALC rescued approximately half of the rubrospinal neurons and spinal motoneurons destined to die, promoted axonal sprouting, restored the density of MAP2 and synaptophysin immunoreactivity and reduced the microglial reaction. However, antioxidant therapy did not affect the reactive astrocytes in the trauma zone. The inflammation modulating properties of ALC were also studied using cultures of human microglial cells. ALC increased the microglial production of interleukin IL-6 and BDNF, thereby possibly mediating the anti-inflammatory and pro-regenerative effects shown in vivo. To study degeneration in the spinal cord following pre-ganglionic and post-ganglionic brachial plexus injuries, adult rat models of ventral root avulsion and peripheral nerve injury were used. A novel MRI protocol was employed and the images were compared to morphological changes found in histological preparations. Ventral root avulsion caused degeneration of dendritic branches and axonal terminals in the spinal cord, followed by significant shrinkage of the ventral horn. Extensive astroglial and microglial reactions were detected in the histological preparations. Peripheral nerve injury reduced the density of dendritic branches but did not cause shrinkage of the ventral horn. Quantitative analysis of MRI images demonstrated changes in the ventral horn following ventral root avulsion only, thus validating the developed MRI technique as a possible tool for the differentiation of pre-ganglionic and post-ganglionic nerve injuries.

  • 316.
    Karalija, Amar
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    The effects of acetyl-­L-­carnitine treatment on neuroinflammation: An in vitro studyManuscript (preprint) (Other academic)
  • 317.
    Karalija, Amar
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Novikova, Liudmila N.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Orädd, Greger
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Novikov, Lev N.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Differentiation of pre- and postganglionic nerve injury using MRI of the spinal cord2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 12, article id e0168807Article in journal (Refereed)
    Abstract [en]

    Brachial plexus injury (BPI) is a devastating type of nerve injury, potentially causing loss of motor and sensory function. Principally, BPI is either categorized as preganglionic or post- ganglionic, with the early establishment of injury level being crucial for choosing the correct treatment strategy. Despite diagnostic advances, the need for a reliable, non-invasive method for establishing the injury level remains. We studied the usefulness of in vivo mag- netic resonance imaging (MRI) of the spinal cord for determination of injury level. The find- ings were related to neuronal and glial changes. Rats underwent unilateral L4 & L5 ventral roots avulsion or sciatic nerve axotomy. The injuries served as models for pre- and postgan- glionic BPI, respectively. MRI of the L4/L5 spinal cord segments 4 weeks after avulsion showed ventral horn (VH) shrinkage on the injured side compared to the uninjured side. Axotomy induced no change in the VH size on MRI. Following avulsion, histological sections of L4/L5 revealed shrinkage in the VH grey matter area occupied by NeuN-positive neurons, loss of microtubular-associated protein-2 positive dendritic branches (MAP2), pan-neurofila- ment positive axons (PanNF), synaptophysin-positive synapses (SYN) and increase in immunoreactivity for the microglial OX42 and astroglial GFAP markers. Axotomy induced no changes in NeuN-reactivity, modest decrease of MAP2 immunoreactivity, no changes in SYN and PanNF labelling, and a modest increase in OX42 and SYN labeling. Histological and radiological findings were congruent when assessing changes after axotomy, while MRI somewhat underestimated the shrinkage. This study indicates a potential diagnostic value of structural spinal cord MRI following BPI. 

  • 318.
    Karalija, Amar
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Novikova, Ludmila N
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Kingham, Paul J
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Novikov, Lev N
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    The effects of N-acetyl-cysteine and acetyl-l-carnitine on neural survival, neuroinflammation and regeneration following spinal cord injury2014In: Neuroscience, ISSN 0306-4522, E-ISSN 1873-7544, Vol. 269, p. 143-151Article in journal (Refereed)
    Abstract [en]

    Traumatic spinal cord injury induces a long-standing inflammatory response in the spinal cord tissue, leading to a progressive apoptotic death of spinal cord neurons and glial cells. We have recently demonstrated that immediate treatment with the antioxidants N-acetyl-cysteine (NAC) and acetyl-l-carnitine (ALC) attenuates neuroinflammation, induces axonal sprouting, and reduces the death of motoneurons in the vicinity of the trauma zone 4weeks after initial trauma. The objective of the current study was to investigate the effects of long-term antioxidant treatment on the survival of descending rubrospinal neurons after spinal cord injury in rats. It also examines the short- and long-term effects of treatment on apoptosis, inflammation, and regeneration in the spinal cord trauma zone. Spinal cord hemisection performed at the level C3 induced a significant loss of rubrospinal neurons 8weeks after injury. At 2weeks, an increase in the expression of the apoptosis-associated markers BCL-2-associated X protein (BAX) and caspase 3, as well as the microglial cell markers OX42 and ectodermal dysplasia 1 (ED1), was seen in the trauma zone. After 8weeks, an increase in immunostaining for OX42 and the serotonin marker 5HT was detected in the same area. Antioxidant therapy reduced the loss of rubrospinal neurons by approximately 50%. Treatment also decreased the expression of BAX, caspase 3, OX42 and ED1 after 2weeks. After 8weeks, treatment decreased immunoreactivity for OX42, whereas it was increased for 5HT. In conclusion, this study provides further insight in the effects of treatment with NAC and ALC on descending pathways, as well as short- and long-term effects on the spinal cord trauma zone.

  • 319.
    Karalija, Nina
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Jonassson, Lars
    Johansson, Jarkko
    Papenberg, Goran
    Salami, Alireza
    Andersson, Micael
    Riklund, Katrine
    Nyberg, Lars
    Boraxbekk, Carl-Johan
    High long-term test-retest reliability for extrastriatal C-11-raclopride binding in healthy older adults2019In: Journal of Cerebral Blood Flow and Metabolism, ISSN 0271-678X, E-ISSN 1559-7016, article id UNSP 0271678X19874770Article in journal (Refereed)
    Abstract [en]

    In vivo dopamine D2-receptor availability is frequently assessed with C-11-raclopride and positron emission tomography. Due to low signal-to-noise ratios for C-11-raclopride in areas with low D2 receptor densities, the ligand has been considered unreliable for measurements outside the dopamine-dense striatum. Intriguingly, recent studies show that extrastriatal C-11-raclopride binding potential (BPND) values are (i) reliably higher than in the cerebellum (where D2-receptor levels are negligible), (ii) correlate with behavior in the expected direction, and (iii) showed good test-retest reliability in a sample of younger adults. The present work demonstrates high seven-month test-retest reliability of striatal and extrastriatal C-11-raclopride BPND values in healthy, older adults (n = 27, age: 64-78 years). Mean C-11-raclopride BPND values were stable between test sessions in subcortical nuclei, and in frontal and temporal cortices (p > 0.05). Across all structures analyzed, intraclass correlation coefficients were high (0.85-0.96), absolute variability was low (mean: 4-8%), and coefficients of variance ranged between 9 and 25%. Furthermore, regional C-11-raclopride BPND values correlated with previously determined F-18-fallypride BPND values (rho = 0.97 and 0.92 in correlations with and without striatal values, respectively, p < 0.01) and postmortem determined D2-receptor densities (including striatum: rho = 0.92; p < 0.001; excluding striatum: rho = 0.75; p = 0.067). These observations suggest that extrastriatal C-11-raclopride measurements represent a true D2 signal.

  • 320.
    Karalija, Nina
    et al.
    Umeå University.
    Papenberg, Goran
    Wåhlin, Anders
    Umeå University.
    Johansson, Jarkko
    Umeå University.
    Andersson, Micael
    Umeå University.
    Axelsson, Jan
    Umeå University.
    Riklund, Katrine
    Umeå University.
    Lövdén, Martin
    Lindenberger, Ulman
    Bäckman, Lars
    Nyberg, Lars
    Umeå University.
    C957T-mediated Variation in Ligand Affinity Affects the Association between C-11-raclopride Binding Potential and Cognition2019In: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 31, no 2, p. 314-325Article in journal (Refereed)
    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.

  • 321.
    Karalija, Nina
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Wåhlin, Anders
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Ek, Jesper
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Rieckmann, Anna
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Papenberg, Goran
    Salami, Alireza
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Wallenberg Centre for Molecular Medicine at Umeå University (WCMM). Aging Research Center, Karolinska Institutet & Stockholm University, Tomtebodavägen 18A,S-17165, Stockholm, Sweden.
    Brandmaier, Andreas M.
    Köhncke, Ylva
    Johansson, Jarkko
    Andersson, Micael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Axelsson, Jan
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Orädd, Greger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Lövdén, Martin
    Lindenberger, Ulman
    Bäckman, Lars
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Cardiovascular factors are related to dopamine integrity and cognition in aging2019In: Annals of clinical and translational neurology, E-ISSN 2328-9503, Vol. 6, no 11, p. 2291-2303Article in journal (Refereed)
    Abstract [en]

    Objective: The aging brain undergoes several changes, including reduced vascular, structural, and dopamine (DA) system integrity. Such brain changes have been associated with age‐related cognitive deficits. However, their relative importance, interrelations, and links to risk factors remain elusive.

    Methods: The present work used magnetic resonance imaging and positron emission tomography with 11C‐raclopride to jointly examine vascular parameters (white‐matter lesions and perfusion), DA D2‐receptor availability, brain structure, and cognitive performance in healthy older adults (n = 181, age: 64–68 years) from the Cognition, Brain, and Aging (COBRA) study.

    Results: Covariance was found among several brain indicators, where top predictors of cognitive performance included caudate and hippocampal integrity (D2DR availability and volumes), and cortical blood flow and regional volumes. White‐matter lesion burden was negatively correlated with caudate DA D2‐receptor availability and white‐matter microstructure. Compared to individuals with smaller lesions, individuals with confluent lesions (exceeding 20 mm in diameter) had reductions in cortical and hippocampal perfusion, striatal and hippocampal D2‐receptor availability, white‐matter microstructure, and reduced performance on tests of episodic memory, sequence learning, and processing speed. Higher cardiovascular risk as assessed by treatment for hypertension, systolic blood pressure, overweight, and smoking was associated with lower frontal cortical perfusion, lower putaminal D2DR availability, smaller grey‐matter volumes, a larger number of white‐matter lesions, and lower episodic memory performance.

    Interpretation: Taken together, these findings suggest that reduced cardiovascular health is associated with poorer status for brain variables that are central to age‐sensitive cognitive functions, with emphasis on DA integrity.

  • 322.
    Karlsson, Fredrik
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Speech and Language Therapy. Umeå University, Faculty of Arts, Department of language studies.
    Unger, Elin
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Speech and Language Therapy.
    Wahlgren, Sofia
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Speech and Language Therapy.
    Doorn, Jan van
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Speech and Language Therapy.
    Treatment effects in voice onset time of plosives associated with deep brain stimulation of the subthalamic nucleus and the caudal zona incerta2012In: Journal of medical speech-language pathology, ISSN 1065-1438, Vol. 20, no 4, p. 65-69Article in journal (Refereed)
    Abstract [en]

    The present study investigated the effect of deep brain stimulation (DBS) of the subthalamic nucleus (STN) and the caudal zona inserta (cZi) on motor control and coordination in plosives. A total of 2520 plosive productions, recorded during production of alternate motion rate and sequential motion rate tasks, were measured for voice onset time (VOT) when measurement was possible. Failed measurements were classified by the underlying cause. The resulting data were analyzed separately for each place of articulation of the intended plosive and compared with the articulatory properties of plosives not meeting the requirements for VOT measurement. The results showed no consistent overall stimulation effect in VOT regardless of place of articulatory closure. Furthermore, no overall pattern concerning the distribution of factors causing failures to measure VOT was observed. Instead, the results suggest a more complex interaction among place of articulation, speech task, and stimulation target in the determination of treatment effects of DBS in patients with Parkinson's disease (PD). The results further suggest that VOT may not provide a robust estimate of treatment effects in articulatory proficiency related to plosive production in patients with PD.

  • 323.
    Karlsson, Lina
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Nordenberg, Robin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Modulering av kortikal excitabilitet i motoriska kortex efter stroke: - en systematisk litteraturgranskning2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Introduktion: Efter stroke sker reorganisering i hjärnan som kan leda till maladaptiv plasticitet och motoriska nedsättningar. Transkraniell magnetisk stimulering (TMS) är en mätmetod med vilken man kan mäta kortikal excitabilitet. TMS är också den vanligaste metoden för att modulera kortikal excitabilitet och används bland annat som behandling för att förbättra motorisk funktion hos strokepatienter.

    Syfte: Syftet med denna studie är att genom en systematisk litteraturgranskning kartlägga vilka moduleringsmetoder, förutom TMS, som använts i syfte att modulera kortikal excitabilitet i motoriska kortex efter stroke, samt se vilken omedelbar effekt de har på kortikal excitabilitet.

    Metod: Mellan den 12 november fram till den 6 december genomfördes en systematisk litteratursökning efter PRISMA-modellen i databaserna; Medline, Pubmed, Cinahl och PEDro. Sökorden som användes var stroke, transcranial magnetic stimulation, rehabilitation och motor cortex excitability. Artiklarna skulle vara publicerade inom de fem senaste åren.

    Resultat: Sökningen resulterade i sju studier med olika moduleringsmetoder. Fem studier visade moduleringsmetoder som gav en ökning av kortikal excitabilitet i motoriska kortex och fyra studier visade moduleringsmetoder som inte gav någon effekt på kortikal excitabilitet i motoriska kortex.

    Konklusion: Resultatet visade att det går att få en omedelbar effekt på kortikal excitabilitet i motoriska kortex vid använding av vissa moduleringsmetoder. En ökning av kortikal excitabilitet skulle kunna bidra till förbättrad motorisk funktion efter stroke. I denna studie valdes de metoder som gav en omedelbar effekt på kortikal excitabilitet vilket gör att studien inte kan uttala om dessa moduleringsmetoder ger effekt även på lång sikt.

  • 324.
    Karlsson, Sari
    et al.
    Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Karlsson, Per
    Department of Clinical Neuroscience, Psychiatry Section, Karolinska Hospital, Stockholm, Sweden.
    Fischer, Håkan
    Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    Thilers, Petra
    Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    MacDonald, Stuart
    Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    Brehmer, Yvonne
    Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    Rieckmann, Anna
    Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    Halldin, Christer
    Department of Clinical Neuroscience, Psychiatry Section, Karolinska Hospital, Stockholm, Sweden.
    Farde, Lars
    Department of Clinical Neuroscience, Psychiatry Section, Karolinska Hospital, Stockholm, Sweden.
    Bäckman, Lars
    Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    Modulation of striatal dopamine D1 binding by cognitive processing2009In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 48, no 2, p. 398-404Article in journal (Refereed)
    Abstract [en]

    There is strong evidence that dopamine (DA) is implicated in higher-order cognitive functioning, but it remains controversial whether D1 receptor binding can be modified by cognitive activity. We examined striatal D1 binding potential (BP) in 20 younger (22-30 years) and 20 older (65-75 years) persons who underwent two [(11)C] SCH 23390 PET measurements, one while resting and one while performing a cognitive task taxing inhibitory functioning. The younger persons showed significant task-related BP reductions in sensorimotor, limbic, and associative striatum during cognitive activity compared to rest. Older persons showed no reliable BP reductions in any striatal subregion. These findings demonstrate that D1 receptor binding can be modified by cognitive activity in younger persons, but also provide novel evidence for the notion that human aging is associated not only with lower DA receptor density but also with altered modifiability of the DA system.

  • 325.
    Karlsson, Sari
    et al.
    Karolinska Institute.
    Rieckmann, Anna
    Karolinska Institute.
    Karlsson, Per
    Karolinska Hospital.
    Farde, Lars
    Karolinska Hospital.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Bäckman, Lars
    Karolinska Institute.
    Relationship of dopamine D1 receptor binding in striatal and extrastriatal regions to cognitive functioning in healthy humans2011In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 57, no 2, p. 346-351Article in journal (Refereed)
    Abstract [en]

    Dopamine (DA) availability in both striatal and extrastriatal brain regions has been implicated in cognitive performance. Given that different brain regions are neuroanatomically and functionally different, DA receptor binding in different brain regions may be selectively important to specific cognitive functions. Using PET and the radioligand SCH23390, we measured D1 receptor binding potential (BP(ND)) in dorsolateral prefrontal cortex (DLPFC), hippocampus (HC), as well as in sensorimotor (SMST), associative (AST), and limbic (LST) striatum in 20 healthy younger persons. Subjects completed tasks assessing executive functioning, episodic memory, speed, and general knowledge. Unlike previous reports, we found no linear or curvilinear relationships between D1 receptor binding in DLPFC and performance in any cognitive task. However, BP(ND) in HC was positively linked to executive performance as well as to speed and knowledge. With regard to the striatal subregions, D1 BP(ND) in SMST was more strongly related to speed compared to the other striatal subregions, whereas D1 BP(ND) in AST was more strongly linked to general knowledge. These findings provide support for the notion that D1 receptors in separate brain regions are differentially related to performance in tasks tapping various cognitive domains.

  • 326.
    Karlsson Wirebring, Linnea
    et al.
    Umeå University, Faculty of Social Sciences, Department of Psychology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Stillesjö, Sara
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Eriksson, Johan
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Juslin, Peter
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    A Similarity-Based Process for Human Judgment in the Parietal Cortex2018In: Frontiers in Human Neuroscience, ISSN 1662-5161, E-ISSN 1662-5161, Vol. 12, article id 481Article in journal (Refereed)
    Abstract [en]

    One important distinction in psychology is between inferences based on associative memory and inferences based on analysis and rules. Much previous empirical work conceive of associative and analytical processes as two exclusive ways of addressing a judgment task, where only one process is selected and engaged at a time, in an either-or fashion. However, related work indicate that the processes are better understood as being in interplay and simultaneously engaged. Based on computational modeling and brain imaging of spontaneously adopted judgment strategies together with analyses of brain activity elicited in tasks where participants were explicitly instructed to perform similarity-based associative judgments or rule-based judgments (n = 74), we identified brain regions related to the two types of processes. We observed considerable overlap in activity patterns. The precuneus was activated for both types of judgments, and its activity predicted how well a similarity-based model fit the judgments. Activity in the superior frontal gyrus predicted the fit of a rule-based judgment model. The results suggest the precuneus as a key node for similarity-based judgments, engaged both when overt responses are guided by similarity-based and rule-based processes. These results are interpreted such that similarity-based processes are engaged in parallel to rule-based-processes, a finding with direct implications for cognitive theories of judgment.

  • 327. Katz, Jonathan S.
    et al.
    Katzberg, Hans D.
    Woolley, Susan C.
    Marklund, Stefan L.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Andersen, Peter M.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Combined fulminant frontotemporal dementia and amyotrophic lateral sclerosis associated with an I113T SOD1 mutation2012In: AMYOTROPH LATERAL SC, ISSN 1748-2968, Vol. 13, no 6, p. 567-569Article in journal (Refereed)
    Abstract [en]

    Mutations in the gene for superoxide dismutase type 1 cause amyotrophic lateral sclerosis (ALS), but are not thought to be associated with frontotemporal dementia (FTD). A lack of detailed case reports is one reason, among others, for this skepticism. This case report comments on a patient with familial ALS caused by I113T mutation in the SOD1 gene presenting with progressive cognitive and behavioral decline two years before developing progressive motor degeneration. In conclusion, this case provides evidence that SOD1 mutations can be associated with FTD.

  • 328. Kaufmann, Horacio
    et al.
    Maurer, Mathew
    Coelho, Teresa
    Plante-Bordeneuve, Violaine
    Rapezzi, Claudio
    Suhr, Ole
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Comparison of US and Non-US Patients with Familial Amyloid Polyneuropathy (FAP) and Familial Amyloid Cardiomyopathy (FAC) in THAOS - The Transthyretin Amyloidosis Outcomes Survey2012In: Neurology, ISSN 0028-3878, E-ISSN 1526-632X, Vol. 78, no Suppl 1, p. P01114-Article in journal (Other academic)
  • 329. Kaufmann, Tobias
    et al.
    van der Meer, Dennis
    Doan, Nhat Trung
    Schwarz, Emanuel
    Lund, Martina J.
    Agartz, Ingrid
    Alnaes, Dag
    Barch, Deanna M.
    Baur-Streubel, Ramona
    Bertolino, Alessandro
    Bettella, Francesco
    Beyer, Mona K.
    Boen, Erlend
    Borgwardt, Stefan
    Brandt, Christine L.
    Buitelaar, Jan
    Celius, Elisabeth G.
    Cervenka, Simon
    Conzelmann, Annette
    Cordova-Palomera, Aldo
    Dale, Anders M.
    de Quervain, Dominique J. F.
    Carlo, PasqualeDi
    Djurovic, Srdjan
    Dorum, Erlend S.
    Eisenacher, Sarah
    Elvsashagen, Torbjorn
    Espeseth, Thomas
    Fatouros-Bergman, Helena
    Flyckt, Lena
    Franke, Barbara
    Frei, Oleksandr
    Haatveit, Beathe
    Haberg, Asta K.
    Harbo, Hanne F.
    Hartman, Catharina A.
    Heslenfeld, Dirk
    Hoekstra, Pieter J.
    Hogestol, Einar A.
    Jernigan, Terry L.
    Jonassen, Rune
    Jonsson, Erik G.
    Kirsch, Peter
    Ktoszewska, Iwona
    Kolskar, Knut K.
    Landro, Nils Inge
    Hellard, StephanieLe
    Lesch, Klaus-Peter
    Lovestone, Simon
    Lundervold, Arvid
    Lundervold, Astri J.
    Maglanoc, Luigi A.
    Malt, Ulrik F.
    Mecocci, Patrizia
    Melle, Ingrid
    Meyer-Lindenberg, Andreas
    Moberget, Torgeir
    Norbom, Linn B.
    Nordvik, Jan Egil
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Oosterlaan, Jaap
    Papalino, Marco
    Papassotiropoulos, Andreas
    Pauli, Paul
    Pergola, Giulio
    Persson, Karin
    Richard, Genevieve
    Rokicki, Jaroslav
    Sanders, Anne-Marthe
    Selbaek, Geir
    Shadrin, Alexey A.
    Smeland, Olav B.
    Soininen, Hilkka
    Sowa, Piotr
    Steen, Vidar M.
    Tsolaki, Magda
    Ulrichsen, Kristine M.
    Vellas, Bruno
    Wang, Lei
    Westman, Eric
    Ziegler, Georg C.
    Zink, Mathias
    Andreassen, Ole A.
    Westlye, Lars T.
    Farde, Lars
    Flyckts, Lena
    Engberg, Goran
    Erhardt, Sophie
    Fatouros-Bergmann, Helena
    Schwieler, Lilly
    Piehl, Fredrik
    Collste, Karin
    Victorsson, Pauliina
    Malmqvist, Anna
    Hedberg, Mikael
    Orhan, Funda
    Common brain disorders are associated with heritable patterns of apparent aging of the brain2019In: Nature Neuroscience, ISSN 1097-6256, E-ISSN 1546-1726, Vol. 22, no 10, p. 1617-+Article in journal (Refereed)
    Abstract [en]

    Common risk factors for psychiatric and other brain disorders are likely to converge on biological pathways influencing the development and maintenance of brain structure and function across life. Using structural MRI data from 45,615 individuals aged 3-96 years, we demonstrate distinct patterns of apparent brain aging in several brain disorders and reveal genetic pleiotropy between apparent brain aging in healthy individuals and common brain disorders.

  • 330.
    Kauppi, Karolina
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Genes to remember: imaging genetics of hippocampus-based memory functions2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the field of imaging genetics, brain function and structure are used as intermediate phenotypes between genes and cognition/diseases to validate and extend findings from behavioral genetics. In this thesis, three of the strongest candidate genes for episodic memory, KIBRA, BDNF, and APOE, were examined in relation to memory performance and hippocampal/parahippocampal fMRI blood-oxygen level-dependent (BOLD) signal. A common T allele in the KIBRA gene was previously associated with superior memory, and increased hippocampal activation was observed in noncarriers of the T allele which was interpreted as reflecting compensatory recruitment. The results from the first study revealed that both memory performance and hippocampal activation at retrieval was higher in T allele carriers (study I). The BDNF 66Met and APOE ε4 alleles have previously been associated with poorer memory performance, but their relation to brain activation has been inconsistent with reports of both increased and decreased regional brain activation relative to noncarriers. Here, decreased hippocampal/parahippocampal activation was observed in carriers of BDNF 66Met (study II) as well as APOE ε4 (study III) during memory encoding. In addition, there was an additive gene-gene effect of APOE and BDNF on hippocampal and parahippocampal activation (study III). Collectively, the results from these studies on KIBRA, BDNF, and APOE converge on higher medial temporal lobe activation for carriers of a high-memory associated allele, relative to carriers of a low-memory associated allele. In addition, the observed additive effect of APOE and BDNF demonstrate that a larger amount of variance in BOLD signal change can be explained by considering the combined effect of more than one genetic polymorphism. These imaging genetics findings support and extend previous knowledge from behavioral genetics on the role of these memory-related genes.

  • 331.
    Kauppi, Karolina
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Nilsson, Lars-Göran
    Stockholm University.
    Adolfsson, Rolf
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Psychiatry.
    Eriksson, Elias
    Gothenburg University.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    KIBRA polymorphism is related to enhanced memory and elevated hippocampal processing2011In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 31, no 40, p. 14218-14222Article in journal (Refereed)
    Abstract [en]

    Several studies have linked the KIBRA rs17070145 T polymorphism to superior episodic memory in healthy humans. One study investigated the effect of KIBRA on brain activation patterns (Papassotiropoulos et al., 2006) and observed increased hippocampal activation in noncarriers of the T allele during retrieval. Noncarriers were interpreted to need more hippocampal activation to reach the same performance level as T carriers. Using large behavioral (N = 2230) and fMRI (N = 83) samples, we replicated the KIBRA effect on episodic memory performance, but found increased hippocampal activation in T carriers during episodic retrieval. There was no evidence of compensatory brain activation in noncarriers within the hippocampal region. In the main fMRI sample, T carriers performed better than noncarriers during scanning but, importantly, the difference in hippocampus activation remained after post hoc matching according to performance, sex, and age (N = 64). These findings link enhanced memory performance in KIBRA T allele carriers to elevated hippocampal functioning, rather than to neural compensation in noncarriers.

  • 332.
    Kauppi, Karolina
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Nilsson, Lars-Göran
    Stockholm University.
    Adolfsson, Rolf
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Psychiatry.
    Lundquist, Anders
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Eriksson, Elias
    Gothenburg University.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Decreased medial temporal lobe activation in BDNF 66Met allele carriers during memory encoding2013In: Neuropsychologia, ISSN 0028-3932, E-ISSN 1873-3514, Vol. 51, no 12, p. 2462-2468Article in journal (Refereed)
    Abstract [en]

    The Met allele of the Brain-derived neurotrophic factor (BDNF) Val(66)Met polymorphism has been associated with impaired activity-dependent secretion of BDNF protein and decreased memory performance. Results from imaging studies relating Val(66)Met to brain activation during memory processing have been inconsistent, with reports of both increased and decreased activation in the Medial Temporal Lobe (MTL) in Met carriers relative to Val homozygotes. Here, we extensively studied BDNF Val(66)Met in relation to brain activation and white matter integrity as well as memory performance in a large imaging (n=194) and behavioral (n=2229) sample, respectively. Functional magnetic resonance imaging (fMRI) was used to investigate MTL activation in healthy participants in the age of 55-75 years during a face-name episodic encoding and retrieval task. White matter integrity was measured using diffusion tensor imaging.

    BDNF Met allele carriers had significantly decreased activation in the MTL during encoding processes, but not during retrieval processes. In contrast to previous proposals, the effect was not modulated by age and the polymorphism was not related to white matter integrity. Met carriers had lower memory performance than Val homozygotes, but differences were subtle and not significant. In conclusion, the BDNF Met allele has a negative influence on MTL functioning, preferentially during encoding processes, which might translate into impaired episodic memory function.

  • 333.
    Kauppi, Karolina
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Nilsson, Lars-Göran
    Department of Psychology, Stockholm University,106 91 Stockholm, Stockholm Brain Institute, Sweden.
    Persson, Jonas
    Aging Research Center (ARC), Karolinska Institutet, Gävlegatan 16, SE-11330 Stockholm, Stockholm University, Sweden.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Additive genetic effect of APOE and BDNF on hippocampus activity2014In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 89, no 1, p. 306-313Article in journal (Refereed)
    Abstract [en]

    Human memory is a highly heritable polygenic trait with complex inheritance patterns. To study the genetics of memory and memory-related diseases, hippocampal functioning has served as an intermediate phenotype. The importance of investigating gene-gene effects on complex phenotypes has been emphasized, but most imaging studies still focus on single polymorphisms. APOE ε4 and BDNF Met, two of the most studied gene variants for variability in memory performance and neuropsychiatric disorders, have both separately been related to poorer episodic memory and altered hippocampal functioning. Here, we investigated the combined effect of APOE and BDNF on hippocampal activation (N=151). No non-additive interaction effects were seen. Instead, the results revealed decreased activation in bilateral hippocampus and parahippocampus as a function of the number of APOE ε4 and BDNF Met alleles present (neither, one, or both). The combined effect was stronger than either of the individual effects, and both gene variables explained significant proportions of variance in BOLD signal change. Thus, there was an additive gene-gene effect of APOE and BDNF on medial temporal lobe (MTL) activation, showing that a larger proportion of variance in brain activation attributed to genetics can be explained by considering more than one gene variant. This effect might be relevant for the understanding of normal variability in memory function as well as memory-related disorders associated with APOE and BDNF.

  • 334.
    Kay, Simon PJ
    et al.
    Leeds General Infirmary.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Thornton, Daniel JA
    Leeds General Infirmary.
    Nerves are living structures whose injury requires urgent repair2010In: Journal of Plastic, Reconstructive & Aesthetic Surgery, ISSN 1748-6815, E-ISSN 1532-1959, Vol. 63, no 12, p. 1939-1940Article in journal (Refereed)
  • 335.
    Keleman, Krystyna
    et al.
    Research Institute of Molecular Pathology, Vienna.
    Kruettner, Sebastian
    Research Institute of Molecular Pathology, Vienna.
    Alenius, Mattias
    Research Institute of Molecular Pathology, Vienna.
    Dickson, Barry J.
    Research Institute of Molecular Pathology, Vienna.
    Function of the Drosophila CPEB protein Orb2 in long-term courtship memory2007In: Nature Neuroscience, ISSN 1097-6256, E-ISSN 1546-1726, Vol. 10, no 12, p. 1587-1593Article in journal (Refereed)
    Abstract [en]

    Both long-term behavioral memory and synaptic plasticity require protein synthesis, some of which may occur locally at specific synapses. Cytoplasmic polyadenylation element-binding (CPEB) proteins are thought to contribute to the local protein synthesis that underlies long-term changes in synaptic efficacy, but a role has not been established for them in the formation of long-term behavioral memory. We found that the Drosophila melanogaster CPEB protein Orb2 is acutely required for long-term conditioning of male courtship behavior. Deletion of the N-terminal glutamine-rich region of Orb2 resulted in flies that were impaired in their ability to form long-term, but not short-term, memory. Memory was restored by expressing Orb2 selectively in fruitless (fru)positive c neurons of the mushroom bodies and by providing Orb2 function in mushroom bodies only during and shortly after training. Our data thus demonstrate that a CPEB protein is important in long-term memory and map the molecular, spatial and temporal requirements for its function in memory formation.

  • 336.
    Keskin, Isil
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Forsgren, Elin
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Lange, Dale J.
    Weber, Markus
    Birve, Anna
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Synofzik, Matthis
    Gilthorpe, Jonathan D.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Andersen, Peter M.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Marklund, Stefan L.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Effects of Cellular Pathway Disturbances on Misfolded Superoxide Dismutase-1 in Fibroblasts Derived from ALS Patients2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 2, article id e0150133Article in journal (Refereed)
    Abstract [en]

    Mutations in superoxide dismutase-1 (SOD1) are a common known cause of amyotrophic lateral sclerosis (ALS). The neurotoxicity of mutant SOD1s is most likely caused by misfolded molecular species, but disease pathogenesis is still not understood. Proposed mechanisms include impaired mitochondrial function, induction of endoplasmic reticulum stress, reduction in the activities of the proteasome and autophagy, and the formation of neurotoxic aggregates. Here we examined whether perturbations in these cellular pathways in turn influence levels of misfolded SOD1 species, potentially amplifying neurotoxicity. For the study we used fibroblasts, which express SOD1 at physiological levels under regulation of the native promoter. The cells were derived from ALS patients expressing 9 different SOD1 mutants of widely variable molecular characteristics, as well as from patients carrying the GGGGCC-repeat-expansion in C9orf72 and from non-disease controls. A specific ELISA was used to quantify soluble, misfolded SOD1, and aggregated SOD1 was analysed by western blotting. Misfolded SOD1 was detected in all lines. Levels were found to be much lower in non-disease control and the non-SOD1 C9orf72 ALS lines. This enabled us to validate patient fibroblasts for use in subsequent perturbation studies. Mitochondrial inhibition, endoplasmic reticulum stress or autophagy inhibition did not affect soluble misfolded SOD1 and in most cases, detergent-resistant SOD1 aggregates were not detected. However, proteasome inhibition led to uniformly large increases in misfolded SOD1 levels in all cell lines and an increase in SOD1 aggregation in some. Thus the ubiquitin-proteasome pathway is a principal determinant of misfolded SOD1 levels in cells derived both from patients and controls and a decline in activity with aging could be one of the factors behind the mid-to late-life onset of inherited ALS.

  • 337. Khademi, Mohsen
    et al.
    Dring, Ann
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Gilthorpe, Jonathan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Wuolikainen, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Al Nimer, Faiez
    Harris, Robert
    Andersson, Magnus
    Brundin, Lou
    Piehl, Fredrik
    Olsson, Tomas
    Svenningsson, Anders
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Multivariate analysis of inflammatory and neuronal injury markers in cerebrospinal fluid of multiple sclerosis: higher levels are associated with younger age2012In: Journal of Neuroimmunology, ISSN 0165-5728, E-ISSN 1872-8421, Vol. 253, no 1-2, p. 100-100Article in journal (Other academic)
  • 338. Khademi, Mohsen
    et al.
    Dring, Ann M.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Gilthorpe, Jonathan D.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Wuolikainen, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Al Nimer, Faiez
    Harris, Robert A.
    Andersson, Magnus
    Brundin, Lou
    Piehl, Fredrik
    Olsson, Tomas
    Svenningsson, Anders
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Intense Inflammation and Nerve Damage in Early Multiple Sclerosis Subsides at Older Age: A Reflection by Cerebrospinal Fluid Biomarkers2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 5, p. e63172-Article in journal (Refereed)
    Abstract [en]

    Inflammatory mediators have crucial roles in leukocyte recruitment and subsequent central nervous system (CNS) neuroinflammation. The extent of neuronal injury and axonal loss are associated with the degree of CNS inflammation and determine physical disability in multiple sclerosis (MS). The aim of this study was to explore possible associations between a panel of selected cerebrospinal fluid biomarkers and robust clinical and demographic parameters in a large cohort of patients with MS and controls (n = 1066) using data-driven multivariate analysis. Levels of matrix metalloproteinase 9 (MMP9), chemokine (C-X-C motif) ligand 13 (CXCL13), osteopontin (OPN) and neurofilament-light chain (NFL) were measured by ELISA in 548 subjects comprising different MS subtypes (relapsing-remitting, secondary progressive and primary progressive), clinically isolated syndrome and persons with other neurological diseases with or without signs of inflammation/infection. Principal component analyses and orthogonal partial least squares methods were used for unsupervised and supervised interrogation of the data. Models were validated using data from a further 518 subjects in which one or more of the four selected markers were measured. There was a significant association between increased patient age and lower levels of CXCL13, MMP9 and NFL. CXCL13 levels correlated well with MMP9 in the younger age groups, but less so in older patients, and after approximately 54 years of age the levels of CXCL13 and MMP9 were consistently low. CXCL13 and MMP9 levels also correlated well with both NFL and OPN in younger patients. We demonstrate a strong effect of age on both inflammatory and neurodegenerative biomarkers in a large cohort of MS patients. The findings support an early use of adequate immunomodulatory disease modifying drugs, especially in younger patients, and may provide a biological explanation for the relative inefficacy of such treatments in older patients at later disease stages.

  • 339.
    Kingham, Paul J
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Kolar, Mallappa K
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Novikova, Liudmila N
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Novikov, Lev N
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Stimulating the neurotrophic and angiogenic properties of human adipose-derived stem cells enhances nerve repair2014In: Stem Cells and Development, ISSN 1547-3287, E-ISSN 1557-8534, Vol. 23, no 7, p. 741-754Article in journal (Refereed)
    Abstract [en]

    In future, adipose-derived stem cells (ASC) might be used to treat neurological disorders. In this study, the neurotrophic and angiogenic properties of human ASC were evaluated, and their effects in a peripheral nerve injury model were determined. In vitro growth factor stimulation of the cells resulted in increased secretion of brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), vascular endothelial growth factor-A (VEGF-A), and angiopoietin-1 proteins. Conditioned medium from stimulated cells increased neurite outgrowth of dorsal root ganglia (DRG) neurons. Similarly, stimulated cells showed an enhanced ability to induce capillary-like tube formation in an in vitro angiogenesis assay. ASC were seeded into a fibrin conduit that was used to bridge a 10 mm rat nerve gap. After 2 weeks, the animals treated with control or stimulated ASC showed an enhanced axon regeneration distance. Stimulated cells evoked more total axon growth. Analysis of regeneration and apoptosis-related gene expression showed that both ASC and stimulated ASC enhanced GAP-43 and activating transcription factor 3 (ATF-3) expression in the spinal cord and reduced c-jun expression in the DRG. Caspase-3 expression in the DRG was reduced by stimulated ASC. Both ASC and stimulated ASC also increased the vascularity of the fibrin nerve conduits. Thus, ASC produce functional neurotrophic and angiogenic factors, creating a more desirable microenvironment for nerve regeneration.

  • 340.
    Kinoshita, Masaharu
    et al.
    National Institute for Physiological Sciences, Myodaiji, Okazaki .
    Matsui, Ryosuke
    Kyoto University.
    Kato, Shigeki
    Fukushima Medical University School of Medicine, Fukushima.
    Hasegawa, Taku
    Kyoto University.
    Kasahara, Hironori
    Kyoto University.
    Isa, Kaoru
    National Institute for Physiological Sciences, Myodaiji, Okazaki .
    Watakabe, Akiya
    National Institute for Basic Biology, Okazaki, he Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa.
    Yamamori, Tetsuo
    National Institute for Basic Biology, Okazaki, he Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa.
    Nishimura, Yukio
    National Institute for Physiological Sciences, Myodaiji, Okazaki .
    Alstermark, Bror
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Watanabe, Dai
    Kyoto University.
    Kobayashi, Kazuto
    Fukushima Medical University School of Medicine, Fukushima.
    Isa, Tadashi
    National Institute for Physiological Sciences, Myodaiji, Okazaki , he Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa.
    Genetic dissection of the circuit for hand dexterity in primates2012In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 487, no 7406, p. 235-U1510Article in journal (Refereed)
    Abstract [en]

    It is generally accepted that the direct connection from the motor cortex to spinal motor neurons is responsible for dexterous hand movements in primates(1-3). However, the role of the 'phylogenetically older' indirect pathways from the motor cortex to motor neurons, mediated by spinal interneurons, remains elusive. Here we used a novel double-infection technique to interrupt the transmission through the propriospinal neurons (PNs)(4-6), which act as a relay of the indirect pathway in macaque monkeys (Macaca fuscata and Macaca mulatta). The PNs were double infected by injection of a highly efficient retrograde gene-transfer vector into their target area and subsequent injection of adeno-associated viral vector at the location of cell somata. This method enabled reversible expression of green fluorescent protein (GFP)-tagged tetanus neurotoxin, thereby permitting the selective and temporal blockade of the motor cortex-PN-motor neuron pathway. This treatment impaired reach and grasp movements, revealing a critical role for the PN-mediated pathway in the control of hand dexterity. Anti-GFP immunohistochemistry visualized the cell bodies and axonal trajectories of the blocked PNs, which confirmed their anatomical connection to motor neurons. This pathway-selective and reversible technique for blocking neural transmission does not depend on cell-specific promoters or transgenic techniques, and is a new and powerful tool for functional dissection in system-level neuroscience studies.

  • 341. Kiss, Zelma H. T.
    et al.
    Hariz, Marwan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    "New and improved" DBS batteries?2019In: Brain Stimulation, ISSN 1935-861X, E-ISSN 1876-4754, Vol. 12, no 4, p. 833-834Article in journal (Other academic)
  • 342. Koehncke, Ylva
    et al.
    Papenberg, Goran
    Jonasson, Lars S.
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Karalija, Nina
    Wåhlin, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Salami, Alireza
    Andersson, Micael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Axelsson, Jan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Bäckman, Lars
    Lindenberger, Ulman
    Lövdén, Martin
    Self-rated intensity of habitual physical activities is positively associated with dopamine D-2/3 receptor availability and cognition2018In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 181, p. 605-616Article in journal (Refereed)
    Abstract [en]

    Between-person differences in cognitive performance in older age are associated with variations in physical activity. The neurotransmitter dopamine (DA) contributes to cognitive performance, and the DA system deteriorates with advancing age. Animal data and a patient study suggest that physical activity modulates DA receptor availability, but data from healthy humans are lacking. In a cross-sectional study with 178 adults aged 64-68 years, we investigated links among self-reported physical activity, D(2/3)DA receptor (D2/3DR) availability, and cognitive performance. D2/3DR availability was measured with [C-11]raclopride positron emission tomography at rest. We used structural equation modeling to obtain latent factors for processing speed, episodic memory, working memory, physical activity, and D2/3DR availability in caudate, putamen, and hippocampus. Physical activity intensity was positively associated with D2/3DR availability in caudate, but not putamen and hippocampus. Frequency of physical activity was not related to D2/3DR availability. Physical activity intensity was positively related to episodic memory and working memory. D2/3DR availability in caudate and hippocampus was positively related to episodic memory. Taken together, our results suggest that striatal DA availability might be a neurochemical correlate of episodic memory that is also associated with physical activity.

  • 343.
    Kokinovic, Bojana
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. epartment of Neuroscience and Brain Technologies (NBT), Italian Institute of Technology (IIT), Genova, Italy.
    Medini, Paolo
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Loss of GABAB-mediated interhemispheric synaptic inhibition in stroke periphery2018In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 596, no 10, p. 1949-1964Article in journal (Refereed)
    Abstract [en]

    Recovery after stroke is mediated by plastic changes largely occurring in the lesion periphery. However, little is known about the microcircuit changes underlying recovery, the extent to which perilesional plasticity occurs at synaptic input vs. spike output level, and the connectivity behind such synaptic plasticity. We combined intrinsic imaging with extracellular and intracellular recordings and pharmacological inactivation in a focal stroke in mouse somatosensory cortex (S1). In vivo whole-cell recordings in hindlimb S1 (hS1) showed synaptic responses also to forelimb stimulation in controls, and such responses were abolished by stroke in the neighbouring forelimb area (fS1), suggesting that, under normal conditions, they originate via horizontal connections from the neighbouring fS1. Synaptic and spike responses to forelimb stimulation in hS1 recovered to quasi-normal levels 2weeks after stroke, without changes in intrinsic excitability and hindlimb-evoked spike responses. Recovered synaptic responses had longer latencies, suggesting a long-range origin of the recovery, prompting us to investigate the role of callosal inputs in the recovery process. Contralesional S1 silencing unmasked significantly larger responses to both limbs in controls, a phenomenon that was not observed when GABAB receptors were antagonized in the recorded area. Conversely, such GABAB-mediated interhemispheric inhibition was not detectable after stroke: callosal input silencing failed to change hindlimb responses, whereas it robustly reduced recovered forelimb responses. Thus, recovery of subthreshold responsiveness in the stroke periphery is accompanied by a loss of interhemispheric inhibition and this is a result of pathway-specific facilitatory action on the affected sensory response from the contralateral cortex.

  • 344.
    Kolar, Mallappa K.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery. Department of Surgical and Perioperative Sciences, Faculty of Medicine.
    Transplantation of mesenchymal stem cells and injections of microRNA as therapeutics for nervous system repair2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Traumatic injuries to the spinal cord (SCI) and peripheral nerve (PNI) affect several thousand people worldwide every year. At present, there is no effective treatment for SCI and despite continuous improvements in microsurgical reconstructive techniques for PNI, many patients are still left with permanent, devastating neurological dysfunction. This thesis investigates the effects of mesenchymal stem cells (MSC) derived from adipose (ASC) and dental (DSC) tissue and chitosan/microRNA-124 polyplex particles on regeneration after spinal cord and peripheral nerve injury in adult rats. Dental stem cells were obtained from apical papilla, dental pulp, and periodontal ligament. ASC and DSC expressed MSC surface markers (CD73, CD90, CD105 and CD146) and various neurotrophic molecules including BDNF, GDNF, NGF, VEGF-A and angiopoietin-1. Growth factor stimulation of the stem cells resulted in increased secretion of these proteins. Both ASC and DSC supported in vitro neurite outgrowth and in contrast to Schwann cells, ASC did not induce activation of astrocytes. Stimulated ASC also showed an enhanced ability to induce capillary-like tube formation in an in vitro angiogenesis assay. In a peripheral nerve injury model, ASC and DSC were seeded into a fibrin conduit, which was used to bridge a 10 mm rat sciatic nerve gap. After 2 weeks, both ASC and DSC promoted axonal regeneration in the conduit and reduced caspase-3 expression in the dorsal root ganglion (DRG). ASC also enhanced GAP-43 and ATF-3 expression in the spinal cord, reduced c-jun expression in the DRG and increased the vascularity of the implant. After transplantation into injured C3-C4 cervical spinal cord, ASC continued to express neurotrophic factors and laminin and stimulated extensive ingrowth of 5HT-positive raphaespinal axons into the trauma zone. In addition, ASC induced sprouting of raphaespinal terminals in C2 contralateral ventral horn and C6 ventral horn on both sides. Transplanted cells also changed the structure and the density of the astroglial scar. Although the transplanted cells had no effect on the density of capillaries around the lesion site, the reactivity of OX42-positive microglial cells was markedly reduced. However, ASC did not enhance recovery of forelimb function. In order to reduce activation of microglia/macrophages and the secondary tissue damage after SCI, the role of microRNA-124 was investigated. In vitro transfection of chitosan/microRNA-124 polyplex particles into rat microglia resulted in the reduction of reactive oxygen species and TNF-α levels and lowered expression of MHC-II. Upon microinjection into uninjured rat spinal cords, particles formed with Cy3-labeled control sequence RNA, were specifically internalized by OX42 positive macrophages and microglia. Alternatively, particles injected in the peritoneum were transported by macrophages to the site of spinal cord injury. Microinjections of chitosan/microRNA-124 particles significantly reduced the number of ED-1 positive macrophages after SCI. In summary, these results show that human MSC produce functional neurotrophic and angiogenic factors, creating a more desirable microenvironment for neural regeneration after spinal cord and peripheral nerve injury. The data also suggests that chitosan/microRNA-124 particles could be potential treatment technique to reduce neuroinflammation.

  • 345.
    Kolar, Mallappa K
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kingham, Paul J
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Novikova, Liudmila N
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Novikov, Lev N
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    The therapeutic effects of human adipose derived stem cells in a rat cervical spinal cord injury model2014In: Stem Cells and Development, ISSN 1547-3287, E-ISSN 1557-8534, Vol. 23, no 14, p. 1659-1674Article in journal (Refereed)
    Abstract [en]

    Spinal cord injury triggers a cascade of degenerative changes leading to cell death and cavitation. Severed axons fail to regenerate across the scar tissue and are only capable of limited sprouting. In this study we investigated the effects of adult human adipose derived stem cells (ASC) on axonal regeneration following transplantation into the injured rat cervical spinal cord. ASC did not induce activation of astrocytes in culture and supported neurite outgrowth from adult rat sensory DRG neurons. After transplantation into the lateral funiculus 1mm rostral and caudal to the cervical C3-C4 hemisection, ASC continued to express BDNF, VEGF and FGF-2 for 3 weeks but only in animals treated with cyclosporine A. Transplanted ASC stimulated extensive ingrowth of 5HT-positive raphaespinal axons into the trauma zone with some terminal arborisations reaching the caudal spinal cord. In addition, ASC induced sprouting of raphaespinal terminals in C2 contralateral ventral horn and C6 ventral horn on both sides. Transplanted cells also changed the structure of the lesion scar with numerous astrocytic processes extended into the middle of the trauma zone in a chain-like pattern and in close association with regenerating axons. The density of the astrocytic network was also significantly decreased. Although the transplanted cells had no effect on the density of capillaries around the lesion site, the activity of OX42-positive microglial cells was markedly reduced. However, ASC did not support recovery of forelimb function. The results suggest that transplanted ASC can modify the structure of the glial scar and stimulate axonal sprouting.

  • 346.
    Kolar, Mallappa Kadappa
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Itte, Vinay N.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Novikov, Lev N.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    The neurotrophic effects of different human dental mesenchymal stem cells2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 12605Article in journal (Refereed)
  • 347.
    Kompus, Kristiina
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Default mode network gates the retrieval of task-irrelevant incidental memories2011In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 487, no 3, p. 318-321Article in journal (Refereed)
    Abstract [en]

    Episodic memories can be retrieved by an intentional search for certain information. Alternatively, a past episode may enter our consciousness without any intention to retrieve it, prompted by a stimulus in our surroundings. Incidental retrieval does not occur upon each encounter with a familiar stimulus, suggesting that a gating mechanism exists which regulates incidental retrieval activity. We analyzed data from a functional magnetic resonance imaging study on incidental retrieval in healthy young adults and found that failure to incidentally retrieve was selectively associated with reduced activation of lateral and medial parietal regions as well as ventromedial frontal cortex, areas implicated in default mode network. This is the first demonstration that relative deactivation of the brain regions associated with the default mode gates the consciousness from currently irrelevant memories.

  • 348.
    Kompus, Kristiina
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). University of Bergen.
    Kalpouzos, Gregoria
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Stockholm University.
    Westerhausen, Rene
    University of Bergen.
    The size of the anterior corpus callosum correlates with the strength of hemispheric encoding-retrieval asymmetry in the ventrolateral prefrontal cortex2011In: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 1419, p. 61-67Article in journal (Refereed)
    Abstract [en]

    Functional lateralization of episodic memory processes in the frontal lobe is an area of intense study in the field of cognitive neuroimaging. Yet, to date there is insufficient knowledge of what role the interhemispheric structural connectivity plays in this lateralized organization. We analyzed functional and structural magnetic resonance imaging data from healthy adult volunteers who performed an associative encoding and retrieval task. We examined the relationship between functional voxel-based relative asymmetry of encoding and retrieval in the frontal lobes and the size of the anterior corpus callosum (antCC; corrected for brain size). The size of the antCC was strongly associated to the relative encoding-retrieval asymmetry in the ventrolateral prefrontal cortex (BA 47). These findings show that the functional asymmetry of episodic memory processes in the frontal lobes is associated with the structural connectivity between the hemispheres. (C) 2011 Elsevier B.V. All rights reserved.

  • 349. Konopacki, Mateusz
    et al.
    Madison, Guy
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    EEG Responses to Shamanic Drumming: Does the Suggestion of Trance State Moderate the Strength of Frequency Components?2018In: Journal of Sleep and Sleep Disorder Research, ISSN 2574-4518, Vol. 1, no 2, p. 16-25Article in journal (Refereed)
    Abstract [en]

    One of the techniques used to induce trance state in shamanic ceremonies is monotonous drumming. According to previous EEG research, certain patterns of drumming cause an increase in power of alpha and theta frequencies of the listener. Present study aimed to determine, if suggestion to experience trance state could increase the relative alpha and theta amplitude and the intensity of experienced state. A group of twenty-four subjects participated in the study. Suggestion to experience trance state decreased alpha frequency power during the drumming condition. No other significant effects of suggestion or drumming were found.

  • 350. Kopra, Jaakko J.
    et al.
    Panhelainen, Anne
    af Bjerken, Sara
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Porokuokka, Lauriina L.
    Varendi, Kart
    Olfat, Soophie
    Montonen, Heidi
    Piepponen, T. Petteri
    Saarma, Mart
    Andressoo, Jaan-Olle
    Dampened Amphetamine-Stimulated Behavior and Altered Dopamine Transporter Function in the Absence of Brain GDNF2017In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 37, no 6, p. 1581-1590Article in journal (Refereed)
    Abstract [en]

    Midbrain dopamine neuron dysfunction contributes to various psychiatric and neurological diseases, including drug addiction and Parkinson's disease. Because of its well established dopaminotrophic effects, the therapeutic potential of glial cell line-derived neurotrophic factor (GDNF) has been studied extensively in various disorders with disturbed dopamine homeostasis. However, the outcomes from preclinical and clinical studies vary, highlighting a need for a better understanding of the physiological role of GDNF on striatal dopaminergic function. Nevertheless, the current lack of appropriate animal models has limited this understanding. Therefore, we have generated novel mouse models to study conditional Gdnf deletion in the CNS during embryonic development and reduction of striatal GDNF levels in adult mice via AAV-Cre delivery. We found that both of these mice have reduced amphetamine-induced locomotor response and striatal dopamine efflux. Embryonic GDNF deletion in the CNS did not affect striatal dopamine levels or dopamine release, but dopamine reuptake was increased due to increased levels of both total and synaptic membrane-associated dopamine transporters. Collectively, these results suggest that endogenous GDNF plays an important role in regulating the function of dopamine transporters in the striatum.

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