| 1. |
- Bäckman, Lars, et al.
(författare)
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Effects of working-memory training on striatal dopamine release
- 2011
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 333:6043, s. 718-
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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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| 2. |
- Dahlin, Erika, 1981-
(författare)
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Train your brain : updating, transfer, and neural changes
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An initial aim of this thesis was to determine whether training of a specific executive function (updating) produces improvements in performance on trained and transfer tasks, and whether the effects are maintained over time. Neural systems underlying training and transfer effects were also investigated and one question considered is whether transfer depends on general or specific neural overlap between training and transfer tasks. An additional aim was to identify how individual differences in executive functioning are mapped to functional brain changes. In Study I, significant training-related changes in performance on the letter memory criterion task were found in both young and older adults after 5 weeks of updating training. Transfer to a 3-back test of updating was also demonstrated in the young adults. Functional Magnetic Resonance Imaging (fMRI) revealed overlapping activity in letter memory and 3-back tasks in fronto-parietal areas and striatum pre-training, and a joint training-related activity increase for the tasks in a striatal region. No transfer was observed to a task (Stroop) that engaged fronto-parietal areas, but not the striatal region and updating per se. Moreover, age-related striatal changes imposed constraints on transfer. In Study II, additional transfer tasks and a test of long-term maintenance were included. Results revealed that training-related gains in performance were maintained 18 months post-training in both young and older adults, whereas transfer effects were limited to tasks requiring updating and restricted to young participants. In Study III, analyses of brain activity and performance during n-back (1/2/3-back) were executed. This task enables manipulation of executive demand, which permits examination of how individual differences in executive functioning can be mapped to functional brain changes. Relative to a young high- performing group, capacity constraints in executive functioning were apparent between 1–2-back for the elderly participants and between 2–3-back for a young low-performing group. Capacity constraints in neural activity followed this pattern by showing a monotonically increasing response in the parietal cortex and the thalamus for young high performers, whereas activity levelled off at 1-back for elderly performers and at 2-back for young low performers. The response in the dorsal frontal cortex followed a similar pattern. Together, these findings indicate that fronto-parietal as well as sub-cortical areas are important for individual differences in executive functioning, training of updating and transfer effects.
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| 3. |
- Dahlin, Erika, 1981-, et al.
(författare)
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Training of the executive component of working memory : subcortial areas mediate transfer effects
- 2009
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Ingår i: Restorative Neurology and Neuroscience. - : IOS Press. - 0922-6028 .- 1878-3627. ; 27:5, s. 405-419
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Several recent studies show that training can improve working memory (WM) performance. In this review, many issues related to WM training, such as neural basis, transfer effects, and age-related changes are addressed. Method: We focus on our own studies investigating training on tasks taxing the executive updating function and discuss our findings in relation to results from other studies investigating training of the executive component of WM. Results: The review confirms positive behavioral effects of training on working memory. The most common neural pattern following training is fronto-parietal activity decreases. Increases in sub-cortical areas are also frequently reported after training, and we suggest that such increases indicate changes in the underlying skill following training. Transfer effects are in general difficult to demonstrate. Some studies show that older adults increase their performance after WM training. However, transfer effects are small or nonexistent in old age. Conclusions: The main finding in this review is that sub-cortical areas seem to have a critical role in mediating transfer effects to untrained tasks after at least some forms of working memory training (such as updating).
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| 4. |
- Nyberg, Lars, 1966-, et al.
(författare)
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Neural correlates of variable working memory load across adult age and skill : dissociative patterns within the fronto-parietal network
- 2009
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Ingår i: Scandinavian Journal of Psychology. - : John Wiley & Sons Inc.. - 0036-5564 .- 1467-9450. ; 50:1, s. 41-46
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Tidskriftsartikel (refereegranskat)abstract
- We examined neural changes related to variations in working memory load by using an n-back task with three levels and functional magnetic resonance imaging. Younger adults were divided into high- and low-performing groups (Young-High; Young-Low) and compared with older adults. Relative to Young-High, capacity-constraints in working memory were apparent between load 1-2 for the elderly and between load 2-3 for Young-Low. Capacity-constraints in neural activity followed this pattern by showing a monotonically increasing response in parietal cortex and thalamus for Young-High, whereas activity leveled off at 1-back for the elderly and at 2-back for Young-Low. The response in dorsal frontal cortex followed a similar pattern with the addition that the magnitude of activation differed within capacity limitations (Old > Young at 1-back; Young-Low > Young-High at 2-back). These findings indicate that an important determinant of WM capacity is the ability to keep the frontal cortex adequately engaged in relation to current task demands.
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| 5. |
- Dahlin, Erika, 1981-, et al.
(författare)
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Plasticity of executive functioning in young and older adults : immediative training gains, transfer, and long-term maintenance
- 2008
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Ingår i: Psychology and Aging. - : American Psychological Association. - 0882-7974 .- 1939-1498. ; 23:4, s. 720-730
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Tidskriftsartikel (refereegranskat)abstract
- The authors investigated immediate training gains, transfer effects, and 18-month maintenance after 5 weeks of computer-based training in updating of information in working memory in young and older subjects. Trained young and older adults improved significantly more than controls on the criterion task (letter memory), and these gains were maintained 18 months later. Transfer effects were in general limited and restricted to the young participants, who showed transfer to an untrained task that required updating (3-back). The findings demonstrate substantial and durable plasticity of executive functioning across adulthood and old age, although there appear to be age-related constraints in the ability to generalize the acquired updating skill.
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| 6. |
- Dahlin, Erika, 1981-, et al.
(författare)
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Transfer of learning after updating training mediated by the striatum
- 2008
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 320:5882, s. 1510-1512
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Tidskriftsartikel (refereegranskat)abstract
- Process-specific training can improve performance on untrained tasks, but the magnitude of gain is variable and often there is no transfer at all. We demonstrate transfer to a 3-back test of working memory after 5 weeks of training in updating. The transfer effect was based on a joint training-related activity increase for the criterion (letter memory) and transfer tasks in a striatal region that also was recruited pretraining. No transfer was observed to a task that did not engage updating and striatal regions, and age-related striatal changes imposed constraints on transfer. These findings indicate that transfer can occur if the criterion and transfer tasks engage specific overlapping processing components and brain regions.
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