Torkel Klingberg was the first to investigate whether intensive training of working memory has beneficial effects on other cognitive functions. His pioneering study suggested that working memory can be improved by training in ADHD patients through computerized programs. This study has found that a period of working memory training increases a range of cognitive abilities and increases IQ test scores. Another study of the same group has shown that, after training, measured brain activity related to working memory increased in the prefrontal cortex, an area that many researchers have associated with working memory functions. It has been shown in one study that working memory training increases the density of prefrontal and parietal dopamine receptors (specifically, DRD1) in test persons. However, subsequent work with the same training program has failed to replicate the beneficial effects of training on cognitive performance. A meta-analytic summary of research with Klingberg's training program up to 2011 shows that this training has at best a negligible effect on tests of intelligence and of attention | Torkel Klingberg was the first to investigate whether intensive training of working memory has beneficial effects on other cognitive functions. His pioneering study suggested that working memory can be improved by training in ADHD patients through computerized programs. This study has found that a period of working memory training increases a range of cognitive abilities and increases IQ test scores. Another study of the same group has shown that, after training, measured brain activity related to working memory increased in the prefrontal cortex, an area that many researchers have associated with working memory functions. It has been shown in one study that working memory training increases the density of prefrontal and parietal dopamine receptors (specifically, DRD1) in test persons. However, subsequent work with the same training program has failed to replicate the beneficial effects of training on cognitive performance. A meta-analytic summary of research with Klingberg's training program up to 2011 shows that this training has at best a negligible effect on tests of intelligence and of attention |