| 1. |
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| 2. |
- Dahlin, Erika, 1981-
(author)
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Train your brain : updating, transfer, and neural changes
- 2009
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Doctoral thesis (other academic/artistic)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. |
- Darki, Fahimeh, et al.
(author)
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DCDC2 polymorphism is associated with left temporoparietal gray and white matter structures during development.
- 2014
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In: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 34:43, s. 14455-62
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Journal article (peer-reviewed)abstract
- Three genes, DYX1C1, DCDC2, and KIAA0319, have been previously associated with dyslexia, neuronal migration, and ciliary function. Three polymorphisms within these genes, rs3743204 (DYX1C1), rs793842 (DCDC2), and rs6935076 (KIAA0319) have also been linked to normal variability of left temporoparietal white matter volume connecting the middle temporal cortex to the angular and supramarginal gyri. Here, we assessed whether these polymorphisms are also related to the cortical thickness of the associated regions during childhood development using a longitudinal dataset of 76 randomly selected children and young adults who were scanned up to three times each, 2 years apart. rs793842 in DCDC2 was significantly associated with the thickness of left angular and supramarginal gyri as well as the left lateral occipital cortex. The cortex was significantly thicker for T-allele carriers, who also had lower white matter volume and lower reading comprehension scores. There was a negative correlation between white matter volume and cortical thickness, but only white matter volume predicted reading comprehension 2 years after scanning. These results show how normal variability in reading comprehension is related to gene, white matter volume, and cortical thickness in the inferior parietal lobe. Possibly, the variability of gray and white matter structures could both be related to the role of DCDC2 in ciliary function, which affects both neuronal migration and axonal outgrowth.
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| 4. |
- Darki, Fahimeh, et al.
(author)
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Human ROBO1 regulates white matter structure in corpus callosum.
- 2017
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In: Brain Structure and Function. - : Springer Science and Business Media LLC. - 1863-2653 .- 1863-2661. ; 222:2, s. 707-716
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Journal article (peer-reviewed)abstract
- The axon guidance receptor, Robo1, controls the pathfinding of callosal axons in mice. To determine whether the orthologous ROBO1 gene is involved in callosal development also in humans, we studied polymorphisms in the ROBO1 gene and variation in the white matter structure in the corpus callosum using both structural magnetic resonance imaging and diffusion tensor magnetic resonance imaging. We found that five polymorphisms in the regulatory region of ROBO1 were associated with white matter density in the posterior part of the corpus callosum pathways. One of the polymorphisms, rs7631357, was also significantly associated with the probability of connections to the parietal cortical regions. Our results demonstrate that human ROBO1 may be involved in the regulation of the structure and connectivity of posterior part of corpus callosum.
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| 5. |
- Darki, Fahimeh, et al.
(author)
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Three dyslexia susceptibility genes, DYX1C1, DCDC2, and KIAA0319, affect temporo-parietal white matter structure.
- 2012
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In: Biological Psychiatry. - : Elsevier BV. - 0006-3223 .- 1873-2402. ; 72:8, s. 671-6
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Journal article (peer-reviewed)abstract
- BACKGROUND: Volume and integrity of white matter correlate with reading ability, but the underlying factors contributing to this variability are unknown.METHODS: We investigated single nucleotide polymorphisms in three genes previously associated with dyslexia and implicated in neuronal migration (DYX1C1, DCDC2, KIAA0319) and white matter volume in a cohort of 76 children and young adults from the general population.RESULTS: We found that all three genes contained polymorphisms that were significantly associated with white matter volume in the left temporo-parietal region and that white matter volume influenced reading ability.CONCLUSIONS: The identified region contained white matter pathways connecting the middle temporal gyrus with the inferior parietal lobe. The finding links previous neuroimaging and genetic results and proposes a mechanism underlying variability in reading ability in both normal and impaired readers.
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| 6. |
- Dumontheil, Iroise, et al.
(author)
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Influence of the COMT genotype on working memory and brain activity changes during development.
- 2011
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In: Biological Psychiatry. - : Elsevier BV. - 0006-3223 .- 1873-2402. ; 70:3, s. 222-9
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Journal article (peer-reviewed)abstract
- BACKGROUND: The Valine158Methionine (Val158Met) polymorphism of the COMT gene leads to lower enzymatic activity and higher dopamine availability in Met carriers. The Met allele is associated with better performance and reduced prefrontal cortex activation during working memory (WM) tasks in adults. Dopaminergic system changes during adolescence may lead to a reduction of basal dopamine levels, potentially affecting Met allele benefits during development.METHODS: We investigated the association of COMT genotype with behavioral (n = 322) and magnetic resonance imaging data (n = 81-84) collected during performance of a visuospatial WM task and potential changes in these effects during development (reflected in age × genotype interactions). Data were collected from a cross-sectional and longitudinal typically developing sample of 6- to 20-year-olds.RESULTS: Visuospatial WM capacity exhibited an age × genotype interaction, with a benefit of the Met allele emerging after 10 years of age. There was a parallel age × genotype interaction on WM-related activation in the right inferior frontal gyrus and intraparietal sulcus (IPS), with increases in activation with age in the Val/Val group only. Main effects of COMT genotype were also observed in the IPS, with greater gray matter volumes bilaterally and greater right IPS activation in the Val/Val group compared with the Met carriers.CONCLUSIONS: These results suggest that COMT genotype effects on WM brain activity and behavior are not static during development. The full developmental picture should be considered when trying to understand the impact of genetic polymorphisms on the mature cognition of healthy adult or psychiatric populations.
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| 7. |
- Edin, Fredrik, et al.
(author)
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Mechanism for top-down control of working memory capacity
- 2009
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In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 106:16, s. 6802-6807
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Journal article (peer-reviewed)abstract
- Working memory capacity, the maximum number of items that we can transiently store in working memory, is a good predictor of our general cognitive abilities. Neural activity in both dorsolateral prefrontal cortex and posterior parietal cortex has been associated with memory retention during visuospatial working memory tasks. The parietal cortex is thought to store the memories. However, the role of the dorsolateral prefrontal cortex, a top-down control area, during pure information retention is debated, and the mechanisms regulating capacity are unknown. Here, we propose that a major role of the dorsolateral prefrontal cortex in working memory is to boost parietal memory capacity. Furthermore, we formulate the boosting mechanism computationally in a biophysical cortical microcircuit model and derive a simple, explicit mathematical formula relating memory capacity to prefrontal and parietal model parameters. For physiologically realistic parameter values, lateral inhibition in the parietal cortex limits mnemonic capacity to a maximum of 2-7 items. However, at high loads inhibition can be counteracted by excitatory prefrontal input, thus boosting parietal capacity. Predictions from the model were confirmed in an fMRI study. Our results show that although memories are stored in the parietal cortex, interindividual differences in memory capacity are partly determined by the strength of prefrontal top-down control. The model provides a mechanistic framework for understanding top-down control of working memory and specifies two different contributions of prefrontal and parietal cortex to working memory capacity.
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| 8. |
- Edin, Fredrik, et al.
(author)
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Stronger fronto-parietal connectivity accounts for development of working memory-related brain activity
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Other publication (other academic/artistic)abstract
- Cognitive functions, including working memory capacity, improve during childhood and early adulthood. Several maturational processes take place during that time, most importantly the myelination of axons, pruning of synapses and strengthening of the remaining synapses. However, it has not yet been shown how to directly relate these cellular changes to working memory development and associated changes in brain activity. Here, we bridge this gap by integrating biophysically-based computational modelling and functional MRI of the visuospatial working memory. Cellular mechanisms corresponding to different maturational processes were implemented in in silico 'child' networks, and the predicted difference in activity between 'child' and a reference 'adult' network was then compared to measured brain activity in children and adults. Network models with stronger connectivity between brain areas, but not networks with faster conduction or increased neuronal specificity, were supported by measured developmental increases in brain activity and correlations between frontal and parietal areas. The 'adult' networks with stronger fronto-parietal connections also exhibited greater stability during distraction, which was consistent with the developmental improvement in working memory performance.
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| 9. |
- Edin, Fredrik, et al.
(author)
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Stronger synaptic connectivity as a mechanism behind development of working memory-related brain activity during childhood
- 2007
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In: Journal of cognitive neuroscience. - : MIT Press - Journals. - 0898-929X .- 1530-8898. ; 19:5, s. 750-760
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Journal article (peer-reviewed)abstract
- The cellular maturational processes behind cognitive development during childhood, including the development of working memory capacity, are still unknown. By using the most standard computational model of visuospatial working memory, we investigated the consequences of cellular maturational processes, including myelination, synaptic strengthening, and synaptic pruning, on working memory-related brain activity and performance. We implemented five structural developmental changes occurring as a result of the cellular maturational processes in the biophysically based computational network model. The developmental changes in memory activity predicted from the simulations of the model were then compared to brain activity measured with functional magnetic resonance imaging in children and adults. We found that networks with stronger fronto-parietal synaptic connectivity between cells coding for similar stimuli, but not those with faster conduction, stronger connectivity within a region, or increased coding specificity, predict measured developmental increases in both working memory-related brain activity and in correlations of activity between regions. Stronger fronto-parietal synaptic connectivity between cells coding for similar stimuli was thus the only developmental process that accounted for the observed changes in brain activity associated with development of working memory during childhood.
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| 10. |
- Einarsdottir, Elisabet, et al.
(author)
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Identification of NCAN as a candidate gene for developmental dyslexia.
- 2017
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1
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Journal article (peer-reviewed)abstract
- A whole-genome linkage analysis in a Finnish pedigree of eight cases with developmental dyslexia (DD) revealed several regions shared by the affected individuals. Analysis of coding variants from two affected individuals identified rs146011974G > A (Ala1039Thr), a rare variant within the NCAN gene co-segregating with DD in the pedigree. This variant prompted us to consider this gene as a putative candidate for DD. The RNA expression pattern of the NCAN gene in human tissues was highly correlated (R > 0.8) with that of the previously suggested DD susceptibility genes KIAA0319, CTNND2, CNTNAP2 and GRIN2B. We investigated the association of common variation in NCAN to brain structures in two data sets: young adults (Brainchild study, Sweden) and infants (FinnBrain study, Finland). In young adults, we found associations between a common genetic variant in NCAN, rs1064395, and white matter volume in the left and right temporoparietal as well as the left inferior frontal brain regions. In infants, this same variant was found to be associated with cingulate and prefrontal grey matter volumes. Our results suggest NCAN as a new candidate gene for DD and indicate that NCAN variants affect brain structure.
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| 11. |
- Einarsdottir, Elisabet, et al.
(author)
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Mutation in CEP63 co-segregating with developmental dyslexia in a Swedish family
- 2015
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In: Human Genetics. - : Springer Science and Business Media LLC. - 0340-6717 .- 1432-1203. ; 134:11-12, s. 1239-1248
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Journal article (peer-reviewed)abstract
- Developmental dyslexia is the most common learning disorder in children. Problems in reading and writing are likely due to a complex interaction of genetic and environmental factors, resulting in reduced power of studies of the genetic factors underlying developmental dyslexia. Our approach in the current study was to perform exome sequencing of affected and unaffected individuals within an extended pedigree with a familial form of developmental dyslexia. We identified a two-base mutation, causing a p.R229L amino acid substitution in the centrosomal protein 63 kDa (CEP63), co-segregating with developmental dyslexia in this pedigree. This mutation is novel, and predicted to be highly damaging for the function of the protein. 3D modelling suggested a distinct conformational change caused by the mutation. CEP63 is localised to the centrosome in eukaryotic cells and is required for maintaining normal centriole duplication and control of cell cycle progression. We found that a common polymorphism in the CEP63 gene had a significant association with brain white matter volume. The brain regions were partly overlapping with the previously reported region influenced by polymorphisms in the dyslexia susceptibility genes DYX1C1 and KIAA0319. We hypothesise that CEP63 is particularly important for brain development and might control the proliferation and migration of cells when those two events need to be highly coordinated.
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| 12. |
- Hassler Hallstedt, Martin, 1973-, et al.
(author)
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Short and Long-Term Effects of a Mathematics Tablet Intervention for Low Performing Second Graders
- 2018
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In: Journal of Educational Psychology. - : American Psychological Association (APA). - 0022-0663 .- 1939-2176. ; 110:8, s. 1127-1148
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Journal article (peer-reviewed)abstract
- Using a randomized placebo controlled design, we examined the direct and follow-up effects (at 6 and 12 months) of a mathematics tablet intervention. Math training focused primarily on basic arithmetic (addition and subtraction facts up to 12), and secondarily on number knowledge and word problems. We investigated the moderating effects of IQ and socioeconomic factors, and additive effects of working memory (WM) training. A representative sample of 283 low performing second-grade students were randomly assigned to control (n = 52), reading placebo (n = 78), math intervention (MA; n = 76), or math plus WM training (MA + WM; n = 77). Both math conditions scored significantly higher than control and placebo on the posttest of basic arithmetic, but not on arithmetic transfer and problem solving. WM training did not show additive effects. Given the virtually identical patterns, we collapsed the control and placebo, respectively, MA and MA + WM conditions. The collapsed MA/MA + WM condition demonstrated significant medium-sized effects (d = 0.53-0.67) on basic arithmetic compared with the collapsed control/placebo condition at posttest. There was a fadeout of effects at 6-month follow-up (d = 0.18 -0.28), that declined further at 12 months (d = 0.03-0.13). IQ was a significant moderator of direct and long-term effects on addition up to 12 and subtraction up to 18, where students with lower IQ benefitted more than higher IQ students. Socioeconomic factors did not moderate outcome. The intervention effectively improved basic arithmetic among low performing second graders. Although the effects waned at 6-month follow-up, there was some indication that children with lower IQ demonstrated sustained gains.Educational Impact and Implications StatementThis study shows that adaptive math training on tablet can help low performing 8-year-olds catch up about half a year of schooling in critical math skills. Students with lower IQ benefitted in particular and made long-term gains 12 months after training finished. Additional short-term memory training did not result in further math improvement. Because math is a strong predictor of later school achievement, these findings highlight the potential of well-designed adaptive teaching on tablets to significantly improve students' success at school. Evidence-based programs covering the bulk of elementary math might be widely spread, potentially at a low cost.
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| 13. |
- Hofmeister, Wolfgang, et al.
(author)
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CTNND2-a candidate gene for reading problems and mild intellectual disability.
- 2015
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In: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 52:2, s. 111-22
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Journal article (peer-reviewed)abstract
- BACKGROUND: Cytogenetically visible chromosomal translocations are highly informative as they can pinpoint strong effect genes even in complex genetic disorders.METHODS AND RESULTS: Here, we report a mother and daughter, both with borderline intelligence and learning problems within the dyslexia spectrum, and two apparently balanced reciprocal translocations: t(1;8)(p22;q24) and t(5;18)(p15;q11). By low coverage mate-pair whole-genome sequencing, we were able to pinpoint the genomic breakpoints to 2 kb intervals. By direct sequencing, we then located the chromosome 5p breakpoint to intron 9 of CTNND2. An additional case with a 163 kb microdeletion exclusively involving CTNND2 was identified with genome-wide array comparative genomic hybridisation. This microdeletion at 5p15.2 is also present in mosaic state in the patient's mother but absent from the healthy siblings. We then investigated the effect of CTNND2 polymorphisms on normal variability and identified a polymorphism (rs2561622) with significant effect on phonological ability and white matter volume in the left frontal lobe, close to cortical regions previously associated with phonological processing. Finally, given the potential role of CTNND2 in neuron motility, we used morpholino knockdown in zebrafish embryos to assess its effects on neuronal migration in vivo. Analysis of the zebrafish forebrain revealed a subpopulation of neurons misplaced between the diencephalon and telencephalon.CONCLUSIONS: Taken together, our human genetic and in vivo data suggest that defective migration of subpopulations of neuronal cells due to haploinsufficiency of CTNND2 contribute to the cognitive dysfunction in our patients.
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| 14. |
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| 15. |
- Klingberg, Torkel, et al.
(author)
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Computerized training of working memory in children with ADHD--a randomized, controlled trial.
- 2005
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In: Journal of the American Academy of Child and Adolescent Psychiatry. - : Elsevier BV. - 0890-8567 .- 1527-5418. ; 44:2, s. 177-186
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Journal article (peer-reviewed)abstract
- OBJECTIVE: Deficits in executive functioning, including working memory (WM) deficits, have been suggested to be important in attention-deficit/hyperactivity disorder (ADHD). During 2002 to 2003, the authors conducted a multicenter, randomized, controlled, double-blind trial to investigate the effect of improving WM by computerized, systematic practice of WM tasks. METHOD: Included in the trial were 53 children with ADHD (9 girls; 15 of 53 inattentive subtype), aged 7 to 12 years, without stimulant medication. The compliance criterion (>20 days of training) was met by 44 subjects, 42 of whom were also evaluated at follow-up 3 months later. Participants were randomly assigned to use either the treatment computer program for training WM or a comparison program. The main outcome measure was the span-board task, a visuospatial WM task that was not part of the training program. RESULTS: For the span-board task, there was a significant treatment effect both post-intervention and at follow-up. In addition, there were significant effects for secondary outcome tasks measuring verbal WM, response inhibition, and complex reasoning. Parent ratings showed significant reduction in symptoms of inattention and hyperactivity/impulsivity, both post-intervention and at follow-up. CONCLUSIONS: This study shows that WM can be improved by training in children with ADHD. This training also improved response inhibition and reasoning and resulted in a reduction of the parent-rated inattentive symptoms of ADHD.
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| 16. |
- Klingberg, Torkel
(author)
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The neurophysiology of working memory : functional mapping of the human brain with positron emission tomography
- 1997
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Doctoral thesis (other academic/artistic)abstract
- Working memory (WM) refers to the retention, or keeping on-line, of information over short periods of time. WM is thought to be important for a variety of cognitive functions, including problem solving, learning and reading. Previous studies in nonhuman primates have mainly implicated sustained neural activity in the prefrontal cortex as the neural correlate of WM. In the present series of experiments, positron emission tomography was used to measure regional cerebral blood flow, a marker of regional metabolic activity, in the brain of human subjects during performance of WM tasks. In paper I, we found that WM for visual, auditory and somatosensory stimuli activated cortical areas with WM specific activity, independent of the sensory modality of the stimulus. These areas were located in the prefrontal, inferior parietal, cingulate and frontal opercular cortex. We hypothesized that activation of the same part of cortex by two different tasks would be associated with interference when these tasks are performed simultaneously. This hypothesis was supported by the results of a series of psychological experiments (paper II). In paper V, both single and dual-task performance of WM tasks was studied. We could show that no additional areas were activated during dual-task performance compared to single task performance. This also implies that there was no area with activation specifically related to divided attention or task-coordination requirements, which has previously been suggested. In paper III, WM for abstract visual stimuli was studied in two delayed matching to sample tasks. In the second matching task the WM load was increased by introducing additional contingencies in the instruction. Both matching tasks activated prefrontal and inferior parietal cortex in the left hemisphere, and the activity in these areas was correlated. The cingulate cortex was activated in the same location as in paper I and V. This cingulate activity is likely due to the planning of a motor response in delayed response tasks such as WM tasks. The increasing WM load in the second matching task induced additional activation in the right prefrontal and inferior parietal cortex. Schizophrenic patients performing this task show impaired performance, and reduced frontal metabolism, compared to control subjects. In paper IV we studied encoding and retrieval from long-term memory, the results suggesting that WM may be necessary to perform tasks involving encoding into long-term memory. In conclusion: a consistent finding in the WM tasks was the coactivation of dorsolateral prefrontal cortex and the middle part of the inferior parietal cortex. This activity was significantly higher during WM tasks than during control tasks involving selective attention. While the prefrontal activation was expected from studies in non human primates, the inferior parietal involvement in WM is a relatively new finding. This area probably has no functionally corresponding area in the non-human primate. Our results also show that two different WM tasks, with memoranda from different sensory modalities, activate overlapping parts of the cortex. This means that information processing during WM tasks is not entirely parallel, but depends on the activation of parts of the cortex which has no modality specificity. Furthermore, we have associated such overlap in activity between tasks with limitations of simultaneous information processing in the brain.
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| 17. |
- Macoveanu, Julian, et al.
(author)
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Neuronal firing rates account for distractor effects on mnemonic accuracy in a visuo-spatial working memory task
- 2007
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In: Biological Cybernetics. - : Springer Science and Business Media LLC. - 0340-1200 .- 1432-0770. ; 96:4, s. 407-419
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Journal article (peer-reviewed)abstract
- Persistent neural activity constitutes one neuronal correlate of working memory, the ability to hold and manipulate information across time, a prerequisite for cognition. Yet, the underlying neuronal mechanisms are still elusive. Here, we design a visuo- spatial delayed-response task to identify the relationship between the cue-distractor spatial distance and mnemonic accuracy. Using a shared experimental and computational test protocol, we probe human subjects in computer experiments, and subsequently we evaluate different neural mechanisms underlying persistent activity using an in silico prefrontal network model. Five modes of action of the network were tested: weak or strong synaptic interactions, wide synaptic arborization, cellular bistability and reduced synaptic NMDA component. The five neural mechanisms and the human behavioral data, all exhibited a significant deterioration of the mnemonic accuracy with decreased spatial distance between the distractor and the cue. A subsequent computational analysis revealed that the firing rate and not the neural mechanism per se, accounted for the positive correlation between mnemonic accuracy and spatial distance. Moreover, the computational modeling predicts an inverse correlation between accuracy and distractibility. In conclusion, any pharmacological modulation, pathological condition or memory training paradigm targeting the underlying neural circuitry and altering the net population firing rate during the delay is predicted to determine the amount of influence of a visual distraction.
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| 18. |
- McNab, Fiona, et al.
(author)
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Common and unique components of inhibition and working memory : An fMRI, within-subjects investigation
- 2008
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In: Neuropsychologia. - : Elsevier BV. - 0028-3932 .- 1873-3514. ; 46:11, s. 2668-2682
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Journal article (peer-reviewed)abstract
- Behavioural findings indicate that the core executive functions of inhibition and working memory are closely linked, and neuroimaging studies indicate overlap between their neural correlates. There has not, however, been a comprehensive study, including several inhibition tasks and several working memory tasks, performed by the same subjects. In the present study, 11 healthy adult subjects completed separate blocks of 3 inhibition tasks (a stop task, a go/no-go task and a flanker task), and 2 working memory tasks (one spatial and one verbal). Activation common to all 5 tasks was identified in the right inferior frontal gyrus, and, at a lower threshold, also the right middle frontal gyrus and right parietal regions (BA 40 and BA 7). Left inferior frontal regions of interest (ROIs) showed a significant conjunction between all tasks except the flanker task. The present study could not pinpoint the specific function of each common region, but the parietal region identified here has previously been consistently related to working memory storage and the right inferior frontal gyrus has been associated with inhibition in both lesion and imaging studies. These results support the notion that inhibitory and working memory tasks involve common neural components, which may provide a neural basis for the interrelationship between the two systems.
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| 19. |
- Olesen, Pernille, et al.
(author)
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Brain activity related to working memory and distraction in children and adults
- 2007
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In: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 17:5, s. 1047-1054
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Journal article (peer-reviewed)abstract
- In order to retain information in working memory (WM) during a delay, distracting stimuli must be ignored. This important ability improves during childhood, but the neural basis for this development is not known. We measured brain activity with functional magnetic resonance imaging in adults and 13-year-old children. Data were analyzed with an event-related design to isolate activity during cue, delay, distraction, and response selection. Adults were more accurate and less distractible than children. Activity in the middle frontal gyrus and intraparietal cortex was stronger in adults than in children during the delay, when information was maintained in WM. Distraction during the delay evoked activation in parietal and occipital cortices in both adults and children. However, distraction activated frontal cortex only in children. The larger frontal activation in response to distracters presented during the delay may explain why children are more susceptible to interfering stimuli.
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| 20. |
- Scerri, Thomas S, et al.
(author)
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The dyslexia candidate locus on 2p12 is associated with general cognitive ability and white matter structure.
- 2012
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:11
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Journal article (peer-reviewed)abstract
- Independent studies have shown that candidate genes for dyslexia and specific language impairment (SLI) impact upon reading/language-specific traits in the general population. To further explore the effect of disorder-associated genes on cognitive functions, we investigated whether they play a role in broader cognitive traits. We tested a panel of dyslexia and SLI genetic risk factors for association with two measures of general cognitive abilities, or IQ, (verbal and non-verbal) in the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort (N>5,000). Only the MRPL19/C2ORF3 locus showed statistically significant association (minimum P = 0.00009) which was further supported by independent replications following analysis in four other cohorts. In addition, a fifth independent sample showed association between the MRPL19/C2ORF3 locus and white matter structure in the posterior part of the corpus callosum and cingulum, connecting large parts of the cortex in the parietal, occipital and temporal lobes. These findings suggest that this locus, originally identified as being associated with dyslexia, is likely to harbour genetic variants associated with general cognitive abilities by influencing white matter structure in localised neuronal regions.
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| 21. |
- Scruggs, Richard, et al.
(author)
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Using Knowledge Tracing to Predict Students’ Performance in Cognitive Training and Math
- 2022
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In: Artificial Intelligence in Education. Posters and Late Breaking Results, Workshops and Tutorials, Industry and Innovation Tracks, Practitioners’ and Doctoral Consortium. - Cham : Springer. - 9783031116469 - 9783031116476 ; , s. 410-413
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Book chapter (peer-reviewed)abstract
- Cognitive training aims to improve skills such as working memory capacity and spatial ability, which have been linked to math skills. In this study, we fit Deep Knowledge Tracing with Transformers (DKTT), Dynamic Key-Value Memory Networks (DKVMN), and Knowledge Tracing Machines (KTM) to a large dataset from a cognitive training system. DKVMN achieved the highest AUC (0.739) of the algorithms. To explore connections between math skills and cognitive skills, the data was split into cognitive and math items. DKVMN’s AUC on the math items was higher (0.745) than on the cognitive (0.706). Notably, the split model AUCs did not differ from skill-level AUCs produced by a model trained on the entire dataset, suggesting that math performance did not improve DKVMN’s cognitive predictions and vice versa.
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| 22. |
- Söderqvist, Stina, et al.
(author)
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Dopamine, working memory, and training induced plasticity : implications for developmental research.
- 2012
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In: Developmental Psychology. - : American Psychological Association (APA). - 0012-1649 .- 1939-0599. ; 48:3, s. 836-43
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Journal article (peer-reviewed)abstract
- Cognitive deficits and particularly deficits in working memory (WM) capacity are common features in neuropsychiatric disorders. Understanding the underlying mechanisms through which WM capacity can be improved is therefore of great importance. Several lines of research indicate that dopamine plays an important role not only in WM function but also for improving WM capacity. For example, pharmacological interventions acting on the dopaminergic system, such as methylphenidate, improve WM performance. In addition, behavioral interventions for improving WM performance in the form of intensive computerized training have recently been associated with changes in dopamine receptor density. These two different means of improving WM performance--pharmacological and behavioral--are thus associated with similar biological mechanisms in the brain involving dopaminergic systems. This article reviews some of the evidence for the role of dopamine in WM functioning, in particular concerning the link to WM development and cognitive plasticity. Novel data are presented showing that variation in the dopamine transporter gene (DAT1) influences improvements in WM and fluid intelligence in preschool-age children following cognitive training. Our results emphasize the importance of the role of dopamine in determining cognitive plasticity.
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| 23. |
- Söderqvist, Stina, et al.
(author)
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Polymorphisms in the dopamine receptor 2 gene region influence improvements during working memory training in children and adolescents.
- 2014
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In: Journal of cognitive neuroscience. - : MIT Press - Journals. - 0898-929X .- 1530-8898. ; 26:1, s. 54-62
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Journal article (peer-reviewed)abstract
- Studying the effects of cognitive training can lead to finding better treatments, but it can also be a tool for investigating factors important for brain plasticity and acquisition of cognitive skills. In this study, we investigated how single-nucleotide polymorphisms (SNPs) and ratings of intrinsic motivation were associated to interindividual differences in improvement during working memory training. The study included 256 children aged 7-19 years who were genotyped for 13 SNPs within or near eight candidate genes previously implicated in learning: COMT, SLC6A3 (DAT1), DRD4, DRD2, PPP1R1B (DARPP32), MAOA, LMX1A, and BDNF. Ratings on the intrinsic motivation inventory were also available for 156 of these children. All participants performed at least 20 sessions of working memory training, and performance during the training was logged and used as the outcome variable. We found that two SNPs, rs1800497 and rs2283265, located near and within the dopamine receptor 2 (DRD2) gene, respectively, were significantly associated with improvements during training (p < .003 and p < .0004, respectively). Scores from a questionnaire regarding intrinsic motivation did not correlate with training outcome. However, we observed both the main effect of genotype at those two loci as well as the interaction between genotypes and ratings of intrinsic motivation (perceived competence). Both SNPs have previously been shown to affect DRD2 receptor density primarily in the BG. Our results suggest that genetic variation is accounting for some interindividual differences in how children acquire cognitive skills and that part of this effect is also seen on intrinsic motivation. Moreover, they suggest that dopamine D2 transmission in the BG is a key factor for cognitive plasticity.
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| 24. |
- Söderqvist, Stina, et al.
(author)
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The SNAP25 gene is linked to working memory capacity and maturation of the posterior cingulate cortex during childhood.
- 2010
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In: Biological Psychiatry. - : Elsevier BV. - 0006-3223 .- 1873-2402. ; 68:12, s. 1120-5
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Journal article (peer-reviewed)abstract
- BACKGROUND: Working memory (WM) is the ability to retain task relevant information. This ability is important for a wide range of cognitive tasks, and WM deficits are a central cognitive impairment in neurodevelopment disorders such as attention-deficit/hyperactivity disorder (ADHD). Although WM capacity is known to be highly heritable, most genes involved remain unidentified.METHODS: Single nucleotide polymorphisms in genes previously associated with cognitive functions or ADHD were selected for genotyping. Associations of these with WM tasks were investigated in a community sample of 330 children and young adults. One single nucleotide polymorphisms was also investigated in an independent sample of 88 4-year-old children. Furthermore, association between brain structure and activity, as measured by magnetic resonance imaging techniques, and single nucleotide polymorphisms alleles were estimated in 88 participants.RESULTS: Genotype at rs363039, located in the gene coding for synaptosomal-associated protein, 25 kDa (SNAP25) was associated to WM capacity in both samples. Associations in the community sample were also found with measures of other cognitive functions. In addition, this polymorphism affected the gray matter and brain activity in the posterior cingulate cortex, an area included in the so-called default mode network previously correlated to regulation of attention and hypothesized to be implicated in ADHD.CONCLUSIONS: A novel gene-brain-behavior network was identified in which a genotype located in SNAP25 affects WM and has age-dependent effects on both brain structure and brain activity. Identifying such networks could be a key to better understanding cognitive development as well as some of its disorders.
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| 25. |
- Thorell, Lisa B., et al.
(author)
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Training and transfer effects of executive functions in preschool children
- 2009
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In: Developmental Science. - : Wiley. - 1363-755X .- 1467-7687. ; 12:1, s. 106-113
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Journal article (peer-reviewed)abstract
- Executive functions, including working memory and inhibition, are of central importance to much of human behavior. Interventions intended to improve executive functions might therefore serve an important purpose. Previous studies show that working memory can be improved by training, but it is unknown if this also holds for inhibition, and whether it is possible to train executive functions in preschoolers. In the present study, preschool children received computerized training of either visuo-spatial working memory or inhibition for 5 weeks. An active control group played commercially available computer games, and a passive control group took part in only pre- and posttesting. Children trained on working memory improved significantly on trained tasks; they showed training effects on non-trained tests of spatial and verbal working memory, as well as transfer effects to attention. Children trained on inhibition showed a significant improvement over time on two out of three trained task paradigms, but no significant improvements relative to the control groups on tasks measuring working memory or attention. In neither of the two interventions were there effects on non-trained inhibitory tasks. The results suggest that working memory training can have significant effects also among preschool children. The finding that inhibition could not be improved by either one of the two training programs might be due to the particular training program used in the present study or possibly indicate that executive functions differ in how easily they can be improved by training, which in turn might relate to differences in their underlying psychological and neural processes.
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