Working memory (WM) capacity is the ability to retain and manipulate information during a short period of time. This ability underlies complex reasoning and has generally been regarded as a ®xed trait of the individual. Children with attention de®cit hyperactivity disorder (ADHD) represent one group of subjects with a WM de®cit, attributed to an impairment of the frontal lobe. In the present study, we used a new training paradigm with intensive and adaptive training of WM tasks and evaluated the effect of training with a double blind, placebo controlled design. Training signi®cantly enhanced performance on the trained WM tasks. More importantly, the training signi®cantly improved performance on a nontrained visuo-spatial WM task and on Raven's Progressive Matrices, which is a nonverbal complex reasoning task. In addition, motor activity ± as measured by the number of head movements during a computerized test ± was signi®cantly reduced in the treatment group. A second experiment showed that similar training-induced improvements on cognitive tasks are also possible in young adults without ADHD. These results demonstrate that performance on WM tasks can be signi®cantly improved by training, and that the training effect also generalizes to nontrained tasks requiring WM. Training improved performance on tasks related to prefrontal functioning and had also a signi®cant effect on motor activity in children with ADHD. The results thus suggest that WM training potentially could be of clinical use for ameliorating the symptoms in ADHD.

No abstract

Working memory (WM) capacity is the ability to retain and manipulate information during a short period of time. This ability underlies complex reasoning and has generally been regarded as a ®xed trait of the individual. Children with attention de®cit hyperactivity disorder (ADHD) represent one group of subjects with a WM de®cit, attributed to an impairment of the frontal lobe. In the present study, we used a new training paradigm with intensive and adaptive training of WM tasks and evaluated the effect of training with a double blind, placebo controlled design. Training signi®cantly enhanced performance on the trained WM tasks. More importantly, the training signi®cantly improved performance on a nontrained visuo-spatial WM task and on Raven's Progressive Matrices, which is a nonverbal complex reasoning task. In addition, motor activity ± as measured by the number of head movements during a computerized test ± was signi®cantly reduced in the treatment group. A second experiment showed that similar training-induced improvements on cognitive tasks are also possible in young adults without ADHD. These results demonstrate that performance on WM tasks can be signi®cantly improved by training, and that the training effect also generalizes to nontrained tasks requiring WM. Training improved performance on tasks related to prefrontal functioning and had also a signi®cant effect on motor activity in children with ADHD. The results thus suggest that WM training potentially could be of clinical use for ameliorating the symptoms in ADHD.

Working memory capacity has traditionally been thought to be constant. Recent studies, however, suggest that working memory can be improved by training. In this study, we have investigated the changes in brain activity that are induced by working memory training. Two experiments were carried out in which healthy, adult human subjects practiced working memory tasks for 5 weeks. Brain activity was measured with functional magnetic resonance imaging (fMRI) before, during and after training. After training, brain activity that was related to working memory increased in the middle frontal gyrus and superior and inferior parietal cortices. The changes in cortical activity could be evidence of training-induced plasticity in the neural systems that underlie working memory.

Our capacity to store information in working memory might be determined by the degree to which only relevant information is remembered. The question remains as to how this selection of relevant items to be remembered is accomplished. Here we show that activity in the prefrontal cortex and basal ganglia preceded the filtering of irrelevant information and that activity, particularly in the globus pallidus, predicted the extent to which only relevant information is stored. The preceding frontal and basal ganglia activity were also associated with inter-individual differences in working memory capacity. These findings reveal a mechanism by which frontal and basal ganglia activity exerts attentional control over access to working memory storage in the parietal cortex in humans, and makes an important contribution to inter-individual differences in working memory capacity.

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.

Abstract& In the human brain, myelination of axons continues until early adulthood and is thought to be important for the development of cognitive functions during childhood. We used diffusion tensor MR imaging and calculated fractional anisotropy, an indicator of myelination and axonal thickness, in children aged between 8 and 18 years. Development of working memory capacity was positively correlated with fractional anisotropy in two regions in the left frontal lobe, including a region between the superior frontal and parietal cortices.Reading ability, on the other hand, was only correlated with fractional anisotropy in the left temporal lobe, in the same white matter region where adults with reading disability are known to have lower fractional anisotropy. Both the temporal and the frontal regions were also correlated with age. These results show that maturation of white matter is an important part of brain maturation during childhood, and that maturation of relatively restricted regions of white matter is correlated with development of specific cognitive functions. &

The primary motor area (M1) of mammals has long been considered to be structurally and functionally homogeneous. This area corresponds to Brodmann's cytoarchitectural area 4. A few reports showing that arm and hand are doubly represented in M1 of macaque monkeys and perhaps man, and that each subarea has separate connections from somatosensory areas, have, with a few exceptions, gone largely unnoticed. Here we show that area 4 in man can be subdivided into areas '4 anterior' (4a) and '4 posterior' (4p) on the basis of both quantitative cytoarchitecture and quantitative distributions of transmitter-binding sites. We also show by positron emission tomography that two representations of the fingers exist, one in area 4a and one in area 4p. Roughness discrimination activated area 4p significantly more than a control condition of self-generated movements. We therefore suggest that the primary motor area is subdivided on the basis of anatomy, neurochemistry and function.