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Sökning: WFRF:(Bäckman Lars) > (2010-2014)

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1.
  • Bäckman, Lars, et al. (författare)
  • Dopamine D(1) receptors and age differences in brain activation during working memory
  • 2011
  • Ingår i: Neurobiology of Aging. - Fayetteville, N.Y : Elsevier. - 0197-4580 .- 1558-1497. ; 32:10, s. 1849-1856
  • Tidskriftsartikel (refereegranskat)abstract
    • In an fMRI study, 20 younger and 20 healthy older adults were scanned while performing a spatial working-memory task under two levels of load. On a separate occasion, the same subjects underwent PET measurements using the radioligand [(11)C] SCH23390 to determine dopamine D(1) receptor binding potential (BP) in caudate nucleus and dorsolateral prefrontal cortex (DLPFC). The fMRI study revealed a significant load modulation of brain activity (higher load>lower load) in frontal and parietal regions for younger, but not older, adults. The PET measurements showed marked age-related reductions of D(1) BP in caudate and DLPFC. Statistical control of caudate and DLPFC D(1) binding eliminated the age-related reduction in load-dependent BOLD signal in left frontal cortex, and attenuated greatly the reduction in right frontal and left parietal cortex. These findings suggest that age-related alterations in dopaminergic neurotransmission may contribute to underrecruitment of task-relevant brain regions during working-memory performance in old age.
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2.
  • de Frias, Cindy M., et al. (författare)
  • Influence of COMT Gene Polymorphism on fMRI-assessed Sustained and Transient Activity during a Working Memory Task
  • 2010
  • Ingår i: Journal of cognitive neuroscience. - Cambridge, Mass. : MIT Press. - 0898-929X .- 1530-8898. ; 22:7, s. 1614-1622
  • Tidskriftsartikel (refereegranskat)abstract
    • The catechol O-methyltransferase (COMT) gene-encoding an enzyme that is essential for the degradation of dopamine (DA) in prefrontal cortex (PFC)-contains a single nucleotide polymorphism (val/met) important for cognition. According to the tonic-phasic hypothesis, individuals carrying the low-enzyme- activity allele (met) are characterized by enhanced tonic DA activity in PFC, promoting sustained cognitive representations in working memory. Val carriers have reduced tonic but enhanced phasic dopaminergic activity in subcortical regions, enhancing cognitive flexibility. We tested the tonic-phasic DA hypothesis by dissociating sustained and transient brain activity during performance on a 2-back working memory test using mixed blocked/event-related functional magnetic resonance imaging. Participants were men recruited from a random sample of the population (the Betula study) and consisted of 11 met/met and 11 val/val carriers aged 50 to 65 years, matched on age, education, and cognitive performance. There were no differences in 2-back performance between genotype groups. Met carriers displayed a greater transient medial temporal lobe response in the updating phase of working memory, whereas val carriers showed a greater sustained PFC activation in the maintenance phase. These results support the tonic-phasic theory of DA function in elucidating the specific phenotypic influence of the COMT val(158)met polymorphism on different components of working memory.
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4.
  • Jonasson, Lars S., et al. (författare)
  • Dopamine release in nucleus accumbens during rewarded task switching measured by [C-11]raclopride
  • 2014
  • Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 99, s. 357-364
  • Tidskriftsartikel (refereegranskat)abstract
    • Reward and motivation have positive influences on cognitive-control processes in numerous settings. Models of reward implicate corticostriatal loops and the dopamine (DA) system, with special emphasis on D-2 receptors in nucleus accumbens (NAcc). In this study, 11 right-handed males (35-40 years) were scanned with positron emission tomography (PET) in a single [C-11]raclopride dynamic scan during rewarded and non-rewarded task switching. Rewarded task switching (relative to baseline task switching) decreased [11C]raclopride binding in NAcc. Decreasing NAcc [C-11]raclopride binding was strongly associated with task reaction time measures that reflect individual differences in effort and control strategies. Voxelwise analyses additionally revealed reward-related DA release in anterodorsal caudate, a region previously associated with task-switching. These PET findings provide evidence for striatal DA release during motivated cognitive control, and further suggest that NAcc DA release predicts the task reaction time benefits of reward incentives.
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5.
  • Karlsson, Sari, et al. (författare)
  • Relationship of dopamine D1 receptor binding in striatal and extrastriatal regions to cognitive functioning in healthy humans
  • 2011
  • Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 57:2, s. 346-351
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
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6.
  • Plaven-Sigray, Pontus, et al. (författare)
  • Dopamine D1 receptor availability is related to social behavior : A positron emission tomography study
  • 2014
  • Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 102, s. 590-595
  • Tidskriftsartikel (refereegranskat)abstract
    • Dysfunctional interpersonal behavior is thought to underlie a wide spectrum of psychiatric disorders; however, the neurobiological underpinnings of these behavioral disturbances are poorly understood. Previous molecular imaging studies have shown associations between striatal dopamine (DA) D2-receptor binding and interpersonal traits, such as social conformity. The objective of this study was to explore, for the first time, the role of DA D1-receptors (D1-Rs) in human interpersonal behavior. Twenty-three healthy subjects were examined using positron emission tomography and the radioligand [C-11] SCH23390, yielding D1-R binding potential values. Striatal D1-R binding was related to personality scales selected to specifically assess one dimension of interpersonal behavior, namely a combination of affiliation and dominance (i.e., the Social Desirability, Verbal Trait Aggression and Physical Trait Aggression scales from Swedish Universities Scales of Personality). An exploratory analysis was also performed for extrastriatal brain regions. D1-R binding potential values in the limbic striatum(r= .52; p= .015), associative striatum(r= .55; p= .009), and sensorimotor striatum(r= .67; p= .001) were positively related to Social Desirability scores. D1-R binding potential in the limbic striatum (r= -.51; p = .019) was negatively associated with Physical Trait Aggression scores. For extrastriatal regions, Social Desirability scores showed positive correlations in the amygdala (r = .60; p = .006) and medial frontal cortex (r= .60; p = .004). This study provides further support for the role of DA function in the expression of disaffiliative and dominant traits. Specifically, D1-R availability may serve as a marker for interpersonal behavior in humans. Associations were demonstrated for the same dimension of interpersonal behavior as for D2-R, but in the opposite direction, suggesting that the two receptor subtypes are involved in the same behavioral processes, but with different functional roles.
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7.
  • Rieckmann, Anna, et al. (författare)
  • Dopamine D1 Receptor Associations within and between Dopaminergic Pathways in Younger and Elderly Adults : Links to Cognitive Performance
  • 2011
  • Ingår i: Cerebral Cortex. - Oxford : Oxford University Press. - 1047-3211 .- 1460-2199. ; 21:9, s. 2023-2032
  • Tidskriftsartikel (refereegranskat)abstract
    • Age-related dopamine (DA) losses have been extensively demonstrated for the D2 receptor subtype. Comparatively little is known about adult age changes regarding D1 receptors. In this study, we demonstrate marked age-related D1 receptor losses in striatal, limbic, and cortical areas using positron emission tomography and the radioligand [11C]SCH23390 in humans. Interregional correlations of binding potential (BP) values were high for areas within DA pathways in younger and elderly adults alike. Furthermore, interregional correlations in D1 BP between DA pathways were uniformly high in younger adults, indicating that D1 receptor densities in striatal, limbic, and cortical areas are not regulated independently, despite dopaminergic innervation from different midbrain areas. For elderly adults, between-pathway correlations of D1 receptor densities were preserved only between mesolimbic and mesocortical areas, whereas striatal BPs were weakly related to those in limbic and neocortical regions. Importantly, weak between-pathway correlations in elderly adults were found only for the slower half of the sample when BP was estimated during a cognitive interference task. These results suggest that D1 receptor densities in different pathways are not regulated independently in younger adults, but segregate in older age, and that this segregation of D1 receptor systems may be related to age-related cognitive slowing.
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8.
  • Arvidsson, Eva, 1959-, et al. (författare)
  • Vägen framåt
  • 2013
  • Ingår i: Att välja rättvist. - Lund : Studentlitteratur AB. ; , s. 207-214
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • Som vi visat har utvecklingen av metoder och strukturer för öppna prioriteringar i Sverige kommit långt. Många frågor återstår likväl. Under vårt arbete med denna bok har vi identifierat ett antal förbättringsområden och utmaningar som vi avslutningsvis vill lyfta fram. Det rör sig om vilka som ska delta i prioriteringarna, tydliggörande av värdegrunden, behov av bättre kunskap, baserad på både vetenskaplig metod och erfarenhet, och fortsatt utveckling av prioriteringsprocesser på olika nivåer och i olika sammanhang. Även om vi i Sverige skulle nå en god enighet kring principer och kriterier för prioriteringar så kommer vi alltid finna många olika sätt att praktiskt lösa specifika prioriteringsproblem.
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9.
  • Bäckman, Lars, et al. (författare)
  • Effects of working-memory training on striatal dopamine release
  • 2011
  • Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 333:6043, s. 718-
  • Tidskriftsartikel (refereegranskat)abstract
    • Updating of working memory has been associated with striato-frontal brain regions and phasic dopaminergic neurotransmission. We assessed raclopride binding to striatal dopamine (DA) D2 receptors during a letter-updating task and a control condition before and after 5 weeks of updating training. Results showed that updating affected DA activity before training and that training further increased striatal DA release during updating. These findings highlight the pivotal role of transient neural processes associated with D2 receptor activity in working memory.
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10.
  • Bäckman, Lars, et al. (författare)
  • Linking cognitive aging to alterations in dopamine neurotransmitter functioning : Recent data and future avenues
  • 2010
  • Ingår i: Neuroscience and Biobehavioral Reviews. - : Elsevier BV. - 0149-7634 .- 1873-7528. ; 34:5, s. 670-677
  • Forskningsöversikt (refereegranskat)abstract
    • Molecular-imaging studies of dopaminergic neurotransmission measure biomarkers of dopamine (DA), such as the DA transporter and D(1) and D(2) receptor densities in the living brain. These studies indicate that individual differences in DA functions are linked to cognitive performance irrespective of age, and serve as powerful mediators of age-related decline in executive functioning, episodic memory, and perceptual speed. This focused review targets several recent findings pertaining to these relationships. Specifically, we discuss novel evidence concerning (a) the role of DA in within-person cognitive variability; (b) age-related differences in DA release during cognitive processing; (c) DA release following cognitive training in younger and older adults; and (d) the relationship between DA and task-induced functional brain activity. Based on these lines of empirical inquiry, we outline a series of avenues for future research on aging, DA, and cognition.
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