| 1. |
- Papenberg, Goran, et al.
(författare)
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Mapping the landscape of human dopamine D2/3 receptors with [11C]raclopride
- 2019
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Ingår i: Brain Structure and Function. - : Springer Science and Business Media LLC. - 1863-2653 .- 1863-2661. ; 224:8, s. 2871-2882
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Tidskriftsartikel (refereegranskat)abstract
- The dopamine D2/3 system is fundamental for sensory, motor, emotional, and cognitive aspects of behavior. Small-scale human histopathological and animal studies show high density of D2/3 dopamine receptors (D2/3DR) in striatum, but also demonstrate the existence of such receptors across cortical and limbic regions. Assessment of D2/3DR BPND in the extrastriatal regions with [C-11]raclopride has long been considered unreliable due to the relatively low density of D2/3DR outside the striatum. We describe the distribution and interregional links of D2/3DR availability measured with PET and [C-11]raclopride across the human brain in a large sample (N = 176; age range 64-68 years). Structural equation modeling revealed that D2/3DR availability can be organized according to anatomical (nigrostriatal, mesolimbic, mesocortical) and functional (limbic, associative, sensorimotor) dopamine pathways. D2/3DR availability in corticolimbic functional subdivisions showed differential associations to corresponding striatal subdivisions, extending animal and pharmacological work. Our findings provide evidence on the dimensionality and organization of [C-11]raclopride D2/3DR availability in the living human brain that conforms to known dopaminergic pathways.
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| 2. |
- Avelar-Pereira, Bárbara, et al.
(författare)
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Age-Related Differences in Dynamic Interactions Among Default Mode, Frontoparietal Control, and Dorsal Attention Networks during Resting-State and Interference Resolution
- 2017
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Ingår i: Frontiers in Aging Neuroscience. - : Frontiers Media S.A.. - 1663-4365 .- 1663-4365. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Resting-state fMRI (rs-fMRI) can identify large-scale brain networks, including the default mode (DMN), frontoparietal control (FPN) and dorsal attention (DAN) networks. Interactions among these networks are critical for supporting complex cognitive functions, yet the way in which they are modulated across states is not well understood. Moreover, it remains unclear whether these interactions are similarly affected in aging regardless of cognitive state. In this study, we investigated age-related differences in functional interactions among the DMN, FPN and DAN during rest and the Multi-Source Interference task (MSIT). Networks were identified using independent component analysis (ICA), and functional connectivity was measured during rest and task. We found that the FPN was more coupled with the DMN during rest and with the DAN during the MSIT. The degree of FPN-DMN connectivity was lower in older compared to younger adults, whereas no age-related differences were observed in FPN-DAN connectivity in either state. This suggests that dynamic interactions of the FPN are stable across cognitive states. The DMN and DAN were anti correlated and age-sensitive during the MSIT only, indicating variation in a task-dependent manner. Increased levels of anticorrelation from rest to task also predicted successful interference resolution. Additional analyses revealed that the degree of DMN-DAN anticorrelation during the MSIT was associated to resting cerebral blood flow (CBF) within the DMN. This suggests that reduced DMN neural activity during rest underlies an impaired ability to achieve higher levels of anticorrelation during a task. Taken together, our results suggest that only parts of age-related differences in connectivity are uncovered at rest and thus, should be studied in the functional connectome across multiple states for a more comprehensive picture.
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| 3. |
- de Boer, Lieke, et al.
(författare)
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Attenuation of dopamine-modulated prefrontal value signals underlies probabilistic reward learning deficits in old age
- 2017
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Ingår i: eLIFE. - : ELIFE SCIENCES PUBLICATIONS LTD. - 2050-084X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Probabilistic reward learning is characterised by individual differences that become acute in aging. This may be due to age-related dopamine (DA) decline affecting neural processing in striatum, prefrontal cortex, or both. We examined this by administering a probabilistic reward learning task to younger and older adults, and combining computational modelling of behaviour, fMRI and PET measurements of DA D1 availability. We found that anticipatory value signals in ventromedial prefrontal cortex (vmPFC) were attenuated in older adults. The strength of this signal predicted performance beyond age and was modulated by D1 availability in nucleus accumbens. These results uncover that a value-anticipation mechanism in vmPFC declines in aging, and that this mechanism is associated with DA D1 receptor availability.
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| 4. |
- de Boer, Lieke, et al.
(författare)
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Dorsal striatal dopamine D1 receptor availability predicts an instrumental bias in action learning
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 116:1, s. 261-270
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Tidskriftsartikel (refereegranskat)abstract
- Learning to act to obtain reward and inhibit to avoid punishment is easier compared with learning the opposite contingencies. This coupling of action and valence is often thought of as a Pavlovian bias, although recent research has shown it may also emerge through instrumental mechanisms. We measured this learning bias with a rewarded go/no-go task in 60 adults of different ages. Using computational modeling, we characterized the bias as being instrumental. To assess the role of endogenous dopamine (DA) in the expression of this bias, we quantified DA D1 receptor availability using positron emission tomography (PET) with the radioligand [11C]SCH23390. Using principal-component analysis on the binding potentials in a number of cortical and striatal regions of interest, we demonstrated that cortical, dorsal striatal, and ventral striatal areas provide independent sources of variance in DA D1 receptor availability. Interindividual variation in the dorsal striatal component was related to the strength of the instrumental bias during learning. These data suggest at least three anatomical sources of variance in DA D1 receptor availability separable using PET in humans, and we provide evidence that human dorsal striatal DA D1 receptors are involved in the modulation of instrumental learning biases.
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| 5. |
- Addario, Barbara, et al.
(författare)
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Characterisation of Schizosaccharomyces pombe alpha-actinin
- 2016
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- The actin cytoskeleton plays a fundamental role in eukaryotic cells. Its reorganization is regulated by a plethora of actin-modulating proteins, such as a-actinin. In higher organisms, alpha-actinin is characterized by the presence of three distinct structural domains: an N-terminal actin-binding domain and a C-terminal region with EF-hand motif separated by a central rod domain with four spectrin repeats. Sequence analysis has revealed that the central rod domain of alpha-actinin from the fission yeast Schizosaccharomyces pombe consists of only two spectrin repeats. To obtain a firmer understanding of the structure and function of this unconventional alpha-actinin, we have cloned and characterized each structural domain. Our results show that this alpha-actinin isoform is capable of forming dimers and that the rod domain is required for this. However, its actin-binding and cross-linking activity appears less efficient compared to conventional alpha-actinins. The solved crystal structure of the actin-binding domain indicates that the closed state is stabilised by hydrogen bonds and a salt bridge not present in other a-actinins, which may reduce the affinity for actin.
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| 6. |
- Backman, Erik, 1972-, et al.
(författare)
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Peer-assessment of technical and tactical skillsin invasion games - possibilities and limitations?
- 2017
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Konferensbidrag (refereegranskat)abstract
- Inom idrottslärarutbildning har detutbildningsinnehåll som handlar om att utveckla studenters ämneskunskaper iidrott kraftigt reducerats under de senaste decennierna. Inte minst har den delav ämneskunskapen som handlar om studenters förmåga att delta i och undervisaom idrottsliga praktiker drabbats (Kirk 2010). När utrymmet för ett ämnesområdebegränsas aktualiseras frågor om innehåll och bedömning. Alltmedan de flestainom fältet är eniga om betydelsen för studenter att få erfarenheter av rörelseoch idrott under sin utbildning finns olika uppfattningar om huruvida man skabedöma studenters förmåga att praktiskt utöva idrott. Hur man förhåller sigdenna fråga har i hög grad visat sig vara kulturellt betingat (Backman &Pearson submitted, Herold & Waring 2009, Siedentop 2009, Tinning 2010). Isvensk idrottslärarutbildning har just den idrottsliga bedömningens vara ellerinte vara visat på en komplexitet och ambivalens (Backman & Pearson 2016).I en tid av alltmer begränsade resurser har problematiken delvis handlat omhuruvida man ska bedöma (och därigenom värdera) studentens förmåga att delta iidrott som ett mål i sig eller om man ska bedöma studentens förmåga attundervisa i och om idrott (Backman & Larsson 2016, Maivorsdotter et al2014). I de studier som belyst den idrottsliga färdighetens position ochbetydelse inom idrottslärarutbildning har studenters röst varit sparsamtförekommande. I denna studie vill vi därför, genom en implementering av eninternationellt etablerad modell för studentmedbedömning i bollspel (GamesPerformance Assessment Instrument, GPAI) (Oslin et al 1998) i kurser förblivande idrottslärare, ge röst åt studenters syn på studentbedömning avförmågan att spela bollspel. I studien har 140 studenter (N=140) pålärarprogrammet vidGymnastik- och idrottshögskolan i Stockholm deltagit. Studien är genomförd inom ramen för en ordinarie bollspelskurs om 3 hp som motsvarar 18 lektionstillfällen med 90 minuters undervisning vid varje tillfälle. Till detta lades två extra lektioner om 90 min för att genomföra studien/datainsamlingen. Studenterna har under och efter kursen bidragit till datainsamlingen i kursen genom ifyllande av etablerade bedömningsformulär där de analyserat varandras spelförmåga. Vidare har studenterna svarat på en utvärdering av hur GPAI implementerats i kursen med hjälp av ett enkätverktyg. Syftet med kursen som studenterna deltagit i är att studenterna ska utveckla sin spelförmåga, leda målspel i skolan samt didaktiska aspekter på målspel i skolan. Studien har omfattat studentmedbedömning i spelen handboll, basket och fotboll som inte enbart ska ses som en utbildning i dessa spel utan som representation för bollspel i allmänhet. Deltagarna i studien representerar alla studenter som hösten 2016 läste den beskrivna kursen. Alla studenter fick information om att deltagandet var frivilligt och att de kunde avbryta när som helst utan att det skulle på verka deras betyg eller vara negativt för dem på något annat sätt. Alla studenter ville vara med i studien. I vår preliminära analys har vi funnit att studenternas observationer av varandra visade på stor variation avseende spelförmåga. I utvärderingen av GPAI-projektet har studenterna uttryckt att de visserligen förstod syftet med GPAI-projektet, och att de förstod hur de skulle bidra till datainsamlingen genom att analysera varandras spelförmåga, men att de var tveksamma till relevansen av GPAI i en bedömningskontext i skolan. Resultaten kommer att analyseras vidare och diskuteras i relation till Shulmans begrepp ämneskunskap (Content Knowledge) och ämnesdidaktisk kunskap (Pedagogical Content Knowledge) samt i relation till teorier om bedömning. I en diskussion där perspektiven ofta begränsas till forskarens och/eller idrottslärarutbildarens kan studenter bidra med viktig kunskap om vad de ser som relevant kunskap för sin kommande yrkesroll. Referenser Backman, E & Pearson, P (submitted) Is movement knowledge common, specialized or pedagogic? Voices of teacher educators on assessment of movement and sport courses in the preparation of Australian HPE teachers. Physical Education and Sport Pedagogy. Backman, E & Pearson, P (2016) “We should assess the students in more authentic situations”. Swedish PE teacher educators’ views of the meaning of movement skills for future PE teachers. European Physical Education Review. 22(1), 47-64. Backman, E & Larsson, H (2016) What should a Physical Education teacher know? An analysis of learning outcomes for future Physical Education teachers in Sweden. Physical Education and Sport Pedagogy. 21(2), 185-200. Herold F and Waring M (2009) Pre-service physical education teachers’ perceptions of subject knowledge: Augmenting learning to teach. European Physical Education Review 15(3): 337–364. Kirk D (2010) Physical Education Futures. Abingdon: Routledge. Oslin, J.L., S.A. Mitchell, & L.L. Griffin. (1998). The Game Performance Assessment Instrument (GPAI): Development and preliminary validation. Journal of Teaching in Physical Education 17(2) p. 231–243. Siedentop D (2009) Content Knowledge for Physical Education. In: Bailey R and Kirk D (eds) The Routledge Physical Education Reader. Abingdon: Routledge, pp. 243-253.Tinning R (2010) Pedagogy and human movement: theory,practice, research. Abingdon: Routledge.
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| 7. |
- Backman, Lars, 1951-
(författare)
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Alpha-actinin of the chlorarchiniophyte Bigelowiella natans
- 2018
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The genome of the chlorarchiniophyte Bigelowiella natans codes for a protein annotated as an α-actinin-like protein. Analysis of the primary sequence indicate that this protein has the same domain structure as other α-actinins, a N-terminal actin-binding domain and a C-terminal calmodulin-like domain. These two domains are connected by a short rod domain, albeit long enough to form a single spectrin repeat. To analyse the functional properties of this protein, the full-length protein as well as the separate domains were cloned and isolated. Characerisation showed that the protein is capable of cross-linking actin filaments into dense bundles, probably due to dimer formation. Similar to human α-actinin, calcium-binding occurs to the most N-terminal EF-hand motif in the calmodulin-like C-terminal domain. The results indicate that this Bigelowiella protein is a proper α-actinin, with all common characteristics of a typical α-actinin.
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| 8. |
- Backman, Lars, 1951-
(författare)
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Calcium affinity of human α-actinin1
- 2015
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Due to alternative splicing, the human ACTN1 gene codes for three different transcripts of α-actinin; one isoform that is expressed only in the brain and two with a more general expression pattern. The sequence difference is located to the C-terminal domains and the EF-hand motifs. Therefore, any functional or structural distinction should involve this part of the protein. To investigate this further, the calcium affinities of these three isoforms of α-actinin 1 have been determined by isothermal calorimetry.
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| 9. |
- Backman, Lars, 1951-, et al.
(författare)
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The no-nonsens SDS-PAGE
- 2018
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Ingår i: Schizosaccharomyces pombe. - New York, NY : Humana Press. - 9781493975457 - 9781493975464 ; , s. 89-94
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The discontinuous polyacrylamide gel electrophoresis system devised by Laemmli (Nature 227:680–685, 1970) has not only been used in numerous laboratories but has also been modified in several ways since its birth. In our laboratories, we use a modified Laemmli SDS-PAGE system for following protein purification as well as for analysis of certain protein-protein interactions, mainly involving filametous actin.
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| 10. |
- Backman, Sofia, et al.
(författare)
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Swedish consensus reached on recording, interpretation and reporting of neonatal continuous simplified electroencephalography that is supported by amplitude-integrated trend analysis
- 2018
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Ingår i: Acta Paediatrica. - : WILEY. - 0803-5253 .- 1651-2227. ; 107:10, s. 1702-1709
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Tidskriftsartikel (refereegranskat)abstract
- Continuous monitoring of electroencephalography (EEG), with a focus on amplitude-integrated EEG (aEEG), has been used in neonatal intensive care for decades. A number of systems have been suggested for describing and quantifying aEEG patterns. Extensive full-montage EEG monitoring is used in specialised intensive care units. The American Clinical Neurophysiology Society published recommendations for defining and reporting EEG findings in critically ill adults and infants. Swedish neonatologists and clinical neurophysiologists collaborated to optimise simplified neonatal continuous aEEG and EEG recordings based on these American documents. Conclusion: This paper describes the Swedish consensus document produced by those meetings.
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