| 1. |
- Bäckman, Lars, et al.
(författare)
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Dopamine D(1) receptors and age differences in brain activation during working memory
- 2011
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Ingår i: Neurobiology of Aging. - Fayetteville, N.Y : Elsevier. - 0197-4580 .- 1558-1497. ; 32:10, s. 1849-1856
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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. |
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| 3. |
- Karlsson, Sari, et al.
(författare)
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Modulation of striatal dopamine D1 binding by cognitive processing
- 2009
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Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 48:2, s. 398-404
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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.
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| 4. |
- Rieckmann, Anna, et al.
(författare)
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Dopamine D1 Receptor Associations within and between Dopaminergic Pathways in Younger and Elderly Adults : Links to Cognitive Performance
- 2011
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Ingår i: Cerebral Cortex. - Oxford : Oxford University Press. - 1047-3211 .- 1460-2199. ; 21:9, s. 2023-2032
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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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| 5. |
- Fischer, Håkan, et al.
(författare)
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Age-related differences in brain regions supporting successful encoding of emotional faces.
- 2010
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Ingår i: Cortex. - Milano : Elsevier BV. - 0010-9452 .- 1973-8102. ; 46:4, s. 490-497
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Tidskriftsartikel (refereegranskat)abstract
- In an event-related functional Magnetic Resonance Imaging (fMRI) study, younger and older adults were presented with negative emotional (i.e., fearful) and neutral face pictures under incidental learning conditions. They were subsequently given a test of face recognition outside the scanner. Both age groups activated amygdala bilaterally as well as the right hippocampus during successful encoding of the fearful faces. Direct age comparisons revealed greater activation in right amygdala and bilateral hippocampus in the young, whereas older adults showed greater activation in the left insular and right prefrontal cortices. None of these brain areas was activated during successful encoding of neutral faces, suggesting specificity of these brain activation patterns. The results indicate an age-related shift in the neural underpinnings of negative emotional face processing from medial-temporal to neocortical regions.
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| 6. |
- Fischer, Håkan, et al.
(författare)
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Brain activation while forming memories of fearful and neutral faces in women and men
- 2007
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Ingår i: Emotion. - : American Psychological Association (APA). - 1528-3542 .- 1931-1516. ; 7:4, s. 767-773
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Event-related functional MRI (fMRI) was used to assess brain activity during encoding of fearful and neutral faces in 12 women and 12 men. In a subsequent memory analysis, the authors separated successful from unsuccessful encoding of both types of faces, based on whether they were remembered or forgotten in a later recognition memory test. Overall, women and men recruited overlapping neural circuitries. Both sexes activated right-sided medial-temporal regions during successful encoding of fearful faces. Successful encoding of neutral faces was associated with left-sided lateral prefrontal and right-sided superior frontal activation in both sexes. In women, relatively greater encoding related activity for neutral faces was seen in the superior parietal and parahippocampal cortices. By contrast, men activated the left and right superior/middle frontal cortex more than women during successful encoding of the same neutral faces. These findings suggest that women and men use similar neural networks to encode facial information, with only subtle sex differences observed for neutral faces.
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| 7. |
- Rypma, Bart, et al.
(författare)
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Dopamine D1 Binding Potential Predicts Fusiform BOLD Activity during Face-Recognition Performance
- 2015
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Ingår i: Journal of Neuroscience. - : Society for Neuroscience. - 0270-6474 .- 1529-2401. ; 35:44, s. 14702-14707
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Tidskriftsartikel (refereegranskat)abstract
- The importance of face memory in humans and primates is well established, but little is known about the neurotransmitter systems involved in face recognition. We tested the hypothesis that face recognition is linked to dopamine (DA) activity in fusiform gyrus (FFG). DA availability was assessed by measuring D1 binding potential (BP) during rest using PET. We further assessed blood-oxygen-level-dependent (BOLD) signal change while subjects performed a face-recognition task during fMRI scanning. There was a strong association between D1 BP and BOLD activity in FFG, whereasD1BPin striatal and other extrastriatal regions were unrelated to neural activity in FFG. These results suggest that D1 BP locally modulates FFG function during face recognition. Observed relationships among D1 BP, BOLD activity, and face-recognition performance further suggest that D1 receptors place constraints on the responsiveness of FFG neurons.
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| 8. |
- Brehmer, Yvonne, et al.
(författare)
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Neural correlates of training-related working-memory gains in old age
- 2011
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 58:4, s. 1110-1120
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Tidskriftsartikel (refereegranskat)abstract
- Working memory (WM) functioning declines in old age. Due to its impact on many higher-order cognitive functions, investigating whether training can modify WM performance has recently been of great interest. We examined the relationship between behavioral performance and neural activity following five weeks of intensive WM training in 23 healthy older adults (M = 63.7 years). 12 participants received adaptive training (i.e. individually adjusted task difficulty to bring individuals to their performance maximum), whereas the others served as active controls (i.e. fixed low-level practice). Brain activity was measured before and after training, using fMRI, while subjects performed a WM task under two difficulty conditions. Although there were no training-related changes in WM during scanning, neocortical brain activity decreased post training and these decreases were larger in the adaptive training group than in the controls under high WM load. This pattern suggests intervention-related increases in neural efficiency. Further, there were disproportionate gains in the adaptive training group in trained as well as in non-trained (i.e. attention, episodic memory) tasks assessed outside the scanner, indicating the efficacy of the training regimen. Critically, the degree of training-related changes in brain activity (i.e. neocortical decreases and subcortical increases) was related to the maximum gain score achieved during the intervention period. This relationship suggests that the decreased activity, but also specific activity increases, observed were functionally relevant.
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| 9. |
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| 10. |
- Gavazzeni, Joachim, et al.
(författare)
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Age, Gender, and Arousal in Recognition of Negative and Neutral Pictures 1 Year Later
- 2012
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Ingår i: Psychology and Aging. - : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 27:4, s. 1039-1052
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Tidskriftsartikel (refereegranskat)abstract
- Compared with nonarousing stimuli, arousing stimuli enhance memory performance. The most robust effects have been reported for negative stimuli, "the negativity effect," although a number of mediating factors prevent definitive conclusions, for example, age, gender, memory task, retention period, and alternative arousal measures. To clarify whether the negativity effect is robust across age, gender, and time, we studied incidental recognition of neutral and negative pictures from the International Affective Picture System (Lang, Bradley, & Cuthbert, 1999) in healthy younger and older adults-women and men-after a 1-year retention interval. Memory performance was related to 2 arousal measures at encoding, skin conductance response (SCR), and intensity rating of unpleasantness. The results showed weaker overall memory performance for older adults compared with younger adults. The negativity effect on accuracy (d') was gender dependent and age independent. In contrast, the negativity effect on response bias (c) interacted with age, but not gender, being weaker for older adults. Despite significant differences in arousal (SCR and arousal rating) between negative and neutral pictures, the correlations between arousal measures and memory performance were weak. Controlling for age and gender, a small negative partial correlation was found between arousal ratings and accuracy. The results extend previous studies by relating long-term recognition to both age and gender as well as to arousal at encoding.
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