| 11. |
- 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.
|
|
| 12. |
- Karalija, Nina, 1984-, et al.
(författare)
-
A common polymorphism in the dopamine transporter gene predicts working memory performance and in vivo dopamine integrity in aging
- 2021
-
Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 245
-
Tidskriftsartikel (refereegranskat)abstract
- Dopamine (DA) integrity is suggested as a potential cause of individual differences in working memory (WM) performance among older adults. Still, the principal dopaminergic mechanisms giving rise to WM differences remain unspecified. Here, 61 single-nucleotide polymorphisms, located in or adjacent to various dopamine-related genes, were assessed for their links to WM performance in a sample of 1313 adults aged 61–80 years from the Berlin Aging Study II. Least Absolute Shrinkage and Selection Operator (LASSO) regression was conducted to estimate associations between polymorphisms and WM. Rs40184 in the DA transporter gene, SLC6A3, showed allelic group differences in WM, with T-carriers performing better than C homozygotes (p<0.01). This finding was replicated in an independent sample from the Cognition, Brain, and Aging study (COBRA; baseline: n = 181, ages: 64–68 years; 5-year follow up: n = 129). In COBRA, in vivo DA integrity was measured with 11C-raclopride and positron emission tomography. Notably, WM as well as in vivo DA integrity was higher for rs40184 T-carriers at baseline (p<0.05 for WM and caudate and hippocampal D2-receptor availability) and at the 5-year follow-up (p<0.05 for WM and hippocampal D2 availability). Our findings indicate that individual differences in DA transporter function contribute to differences in WM performance in old age, presumably by regulating DA availability.
|
|
| 13. |
- Karlsson, Sari, et al.
(författare)
-
Modulation of striatal dopamine D1 binding by cognitive processing
- 2009
-
Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 48:2, s. 398-404
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 14. |
- 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.
|
|
| 15. |
- Köhncke, Ylva, et al.
(författare)
-
Self-rated intensity of habitual physical activities is positively associated with dopamine D-2/3 receptor availability and cognition
- 2018
-
Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 181, s. 605-616
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 16. |
- Lind, Johanna, et al.
(författare)
-
Reduced functional brain activity response in cognitively intact apolipoprotein E ε4 carriers
- 2006
-
Ingår i: Brain. - : Oxford University Press. - 0006-8950 .- 1460-2156. ; 129:5, s. 1240-1248
-
Tidskriftsartikel (refereegranskat)abstract
- The apolipoprotein E epsilon4 (APOE epsilon4) is the main known genetic risk factor for Alzheimer's disease. Genetic assessments in combination with other diagnostic tools, such as neuroimaging, have the potential to facilitate early diagnosis. In this large-scale functional MRI (fMRI) study, we have contrasted 30 APOE epsilon4 carriers (age range: 49-74 years; 19 females), of which 10 were homozygous for the epsilon4 allele, and 30 non-carriers with regard to brain activity during a semantic categorization task. Test groups were closely matched for sex, age and education. Critically, both groups were cognitively intact and thus symptom-free of Alzheimer's disease. APOE epsilon4 carriers showed reduced task-related responses in the left inferior parietal cortex, and bilaterally in the anterior cingulate region. A dose-related response was observed in the parietal area such that diminution was most pronounced in homozygous compared with heterozygous carriers. In addition, contrasts of processing novel versus familiar items revealed an abnormal response in the right hippocampus in the APOE epsilon4 group, mainly expressed as diminished sensitivity to the relative novelty of stimuli. Collectively, these findings indicate that genetic risk translates into reduced functional brain activity, in regions pertinent to Alzheimer's disease, well before alterations can be detected at the behavioural level.
|
|
| 17. |
- Lind, Johanna, et al.
(författare)
-
Reduced hippocampal volume in non-demented carriers fo the apolipoprotein E ε4 : Relation to chronological age and recognition memory
- 2006
-
Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940 .- 1872-7972. ; 396:1, s. 23-27
-
Tidskriftsartikel (refereegranskat)abstract
- Apolipoprotein E ε4 (APOE ε4) is the main known genetic risk factor for Alzheimer's disease (AD). Some previous studies have reported structural brain changes as well as cognitive deficits in non-demented APOE ε4 carriers, but the pattern of results is inconsistent and studies with larger sample sizes have been called for. Here we compared hippocampal volume and recognition–memory performance between AD-symptom-free carriers (N = 30) and non-carriers (N = 30) of the APOE ε4 (age range: 49–79 years). We observed reduced right hippocampal volume in APOE ε4 carriers, and found that the difference was most pronounced before the age of 65. Further, the APOE ε4 carriers made significantly more false alarms in the recognition–memory test, and the number of false alarms correlated significantly with right hippocampus volume. These results indicate that relatively young individuals at genetic risk for AD have smaller hippocampal volume and lower performance on hippocampal-dependent cognitive tasks. A question for the future is whether smaller hippocampal volume represents early-onset hippocampal volume reduction or an inherent trait.
|
|
| 18. |
- Lövdén, Martin, et al.
(författare)
-
Latent-Profile Analysis Reveals Behavioral and Brain Correlates of Dopamine-Cognition Associations
- 2018
-
Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 28:11, s. 3894-3907
-
Tidskriftsartikel (refereegranskat)abstract
- Evidence suggests that associations between the neurotransmitter dopamine and cognition are nonmonotonic and open to modulation by various other factors. The functional implications of a given level of dopamine may therefore differ from person to person. By applying latent-profile analysis to a large (n = 181) sample of adults aged 64-68 years, we probabilistically identified 3 subgroups that explain the multivariate associations between dopamine D2/3R availability (probed with C-11-raclopride-PET, in cortical, striatal, and hippocampal regions) and cognitive performance (episodic memory, working memory, and perceptual speed). Generally, greater receptor availability was associated with better cognitive performance. However, we discovered a subgroup of individuals for which high availability, particularly in striatum, was associated with poor performance, especially for working memory. Relative to the rest of the sample, this subgroup also had lower education, higher body-mass index, and lower resting-state connectivity between caudate nucleus and dorsolateral prefrontal cortex. We conclude that a smaller subset of individuals induces a multivariate non-linear association between dopamine D2/3R availability and cognitive performance in this group of older adults, and discuss potential reasons for these differences that await further empirical scrutiny.
|
|
| 19. |
- MacDonald, Stuart W S, et al.
(författare)
-
Extrastriatal dopamine D2 receptor binding modulates intraindividual variability in episodic recognition and executive functioning.
- 2009
-
Ingår i: Neuropsychologia. - : Elsevier BV. - 0028-3932 .- 1873-3514. ; 47:11, s. 2299-2304
-
Tidskriftsartikel (refereegranskat)abstract
- Intraindividual variability (IIV) reflects lawful but transient within-person changes in performance. Increased IIV in cognition shares systematic associations with numerous conditions characterized by alterations in dopamine (DA) neuromodulation (e.g., old age, ADHD, schizophrenia, and Parkinson's disease). In a group of normal middle-aged adults, we examined links between PET-derived measures of D2 receptor binding in striatum, orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and hippocampus (HC) and IIV for tasks assessing recognition memory and executive functioning. An index of IIV, the intraindividual standard deviation (ISD), was computed across successful response latency trials for each cognitive outcome. Lower D2 binding in OC, ACC, and HC, but not striatum, was associated with increasing ISDs for the memory and executive measures. Consistent with neurocomputational models, the present findings suggest a role for extrastriatal DA neurotransmission in modulating variability in cognitive functioning.
|
|
| 20. |
- Maitland, Scott B., et al.
(författare)
-
On the structure of personality : Are there separate temperament and character factors?
- 2009
-
Ingår i: Personality and Individual Differences. - : Elsevier. - 0191-8869 .- 1873-3549. ; 47:3, s. 180-184
-
Tidskriftsartikel (refereegranskat)abstract
- The Temperament and Character Inventory (TCI) is a widely used measure of psychobiological aspects of personality. Theoretically, the TCI is defined as comprising four temperament and three character factors. Most previous examinations of the factor structure have used exploratory factor methods with mixed results. We used confirmatory factor analyses (CFA) to examine the TCI in a sample of 2423 adults aged 35–90 years (1093 women, 1330 men) from the Betula study. Support for the seven TCI factors was mixed. Models including second-order factors provided no evidence that the seven first-order TCI factors reflect higher-order temperament and character constructs. Our findings provide no support that individual differences on the seven first-order TCI factors reflect distinct temperament or character dimensions of personality. Whereas more complex modeling strategies rejected separate character and temperament models, the simultaneous (seven-factor) model, and the use of second-order factors; the harm avoidance, self-directedness, and cooperativeness factors were acceptable examined individually. Results for novelty seeking were marginal and self-transcendence, reward dependence and/or persistence factors were not acceptable.
|
|
