Trends in Cognitive Sciences
ReviewTraining and plasticity of working memory
Section snippets
Explicit versus implicit training of working memory
Working memory (WM) refers to the retention of information over a brief period of time, a function that is of central importance for a wide range of cognitive tasks and for academic achievement [1]. Impaired WM is observed in many neuropsychiatric conditions, such as traumatic brain injury, stroke, mental retardation, schizophrenia and attention-deficit hyperactivity disorder (ADHD) [2]. It is thus not surprising that attempts to improve WM have a long history. In their 1972 article ‘On the
Psychological and neural correlates of WM
Neurophysiological studies show that maintenance of information in WM is associated with elevated and sustained neural firing over a delay when information is kept in mind [11]. Neuroimaging studies in humans have mapped WM-related activity to both sensory association cortices and prefrontal cortex 12, 13. Some of these regions show specificity to the sensory modality of the stimuli 12, 13. Other regions, including parts of the intraparietal cortex and dorsolateral prefrontal cortex, are
Computerized training of WM
An example of what might be termed implicit WM training is the training program originally developed by Klingberg and colleagues for children with ADHD 34, 35. This training involves repeated performance of WM tasks, with feedback and rewards based on the accuracy for every trial. The effective training time is 30–40 min per day, 5 days a week for 5 weeks (totaling approx. 15 h). The difficulty of the tasks is adjusted during the WM training on a trial-by-trial basis by changing the amount of
WM training focusing on updating
The training program described above focused on training and increasing WM capacity, primarily by increasing the amount of visuospatial information that should be retained. Another approach to WM training also uses the principles of implicit training, but focuses specifically on updating, namely the replacement of old information in a hypothetical WM store with new information 45, 46, 47.
In a study by Dahlin et al., young and old healthy adults practiced three computerized updating tasks for 45
Neural correlates of WM training
Identifying the neural correlates of training-induced improvements has many caveats, since there are many parallel behavioral changes occurring during the course of training (Box 2). Furthermore, the aspects of brain activity associated with superior capacity are still a matter of debate. However, the majority of studies indicate a positive correlation between WM capacity and brain activity in task-relevant areas. Inter-individual differences in WM capacity have been positively correlated with
Concluding remarks
WM training can induce improvements in performance in non-trained tasks that rely on WM and control of attention. This transfer effect is consistent with training-induced plasticity in an intraparietal–prefrontal network that is common for WM and control of attention. Adaptive training that focuses on control of attention could have similar effects and has shown promising results [65].
The observed training effects suggest that WM training could be used as a remediating intervention for
Conflict of interest declaration
TK is a consultant for Cogmed Systems. This company provides software for working memory training used in several of the reviewed articles.
References (82)
Working memory capacity and its relation to general intelligence
Trends Cogn. Sci.
(2003)A meta-analysis of working memory impairments in children with attention-deficit/hyperactivity disorder
J. Am. Acad. Child Adolesc. Psychiatry
(2005)- et al.
Effects of visual experience on the representation of objects in the prefrontal cortex
Neuron
(2000) - et al.
Persistent activity in the prefrontal cortex during working memory
Trends Cogn. Sci.
(2003) Neural correlates of superior intelligence: stronger recruitment of posterior parietal cortex
Neuroimage
(2006)Developmental neural networks in children performing a categorical n-back task
Neuroimage
(2006)Computerized training of working memory in children with ADHD – a randomized, controlled trial
J. Am. Acad. Child Adolesc. Psychiatry
(2005)Development of cognitive control and executive functions from 4 to 13 years: evidence from manipulations of memory, inhibition, and task switching
Neuropsychologia
(2006)Cortical capacity constraints for visual working memory: dissociation of fMRI load effects in a fronto-parietal network
Neuroimage
(2003)A biophysical model of multiple-item working memory: a computational and neuroimaging study
Neuroscience
(2006)