Anna Stigsdotter Neely

Transfer of Learning After Updating Training Mediated by the Striatum

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.

Plasticity of executive functioning in young and older adults: immediate training gains, transfer, and long-term maintenance.

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.

Neural correlates of training-related memory improvement in adulthood and aging

Cognitive studies show that both younger and older adults can increase their memory performance after training in using a visuospatial mnemonic, although age-related memory deficits tend to be magnified rather than reduced after training. Little is known about the changes in functional brain activity that accompany training-induced memory enhancement, and whether age-related activity changes are associated with the size of training-related gains. Here, we demonstrate that younger adults show increased activity during memory encoding in occipito-parietal and frontal brain regions after learning the mnemonic. Older adults did not show increased frontal activity, and only those elderly persons who benefited from the mnemonic showed increased occipito-parietal activity. These findings suggest that age-related differences in cognitive reserve capacity may reflect both a frontal processing deficiency and a posterior production deficiency.

Effects of Working-Memory Training on Striatal Dopamine Release

A cognitive training program that improves working memory is associated with increased dopamine release during task performance. 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.

Cognitive and neural plasticity in aging: General and task-specific limitations

There is evidence for cognitive as well as neural plasticity across the adult life span, although aging is associated with certain constraints on plasticity. In the current paper, we argue that the age-related reduction in cognitive plasticity may be due to (a) deficits in general processing resources, and (b) failure to engage in task-relevant cognitive operations. Memory-training research suggests that age-related processing deficits (e.g., executive functions, speed) hinder older adults from utilizing mnemonic techniques as efficiently as the young, and that this age difference is reflected by diminished frontal activity during mnemonic use. Additional constraints on memory plasticity in old age are related to difficulties that are specific to the task, such as creating visual images, as well as in binding together the information to be remembered. These deficiencies are paralleled by reduced activity in occipito-parietal and medial-temporal regions, respectively. Future attempts to optimize intervention-related gains in old age should consider targeting both general processing and task-specific origins of age-associated reductions in cognitive plasticity.

Neural correlates of variable working memory load across adult age and skill: dissociative patterns within the fronto-parietal network.

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.

Training of the executive component of working memory: subcortical areas mediate transfer effects.

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).

Remembering Numbers in Old Age: Mnemonic Training Versus Self-Generated Strategy Training

The effectiveness of two memory training programs designed to enhance four-digit number recall was examined in 90 healthy older adults. One group received instruction and training in the number-consonant mnemonic, whereas another group was instructed to adopt their own encoding and retrieval strategies to enhance number recall. Also, a control group receiving no training between testing occasions was included. The criterion task was administered according to the Buschke selective reminding procedure. Posttest performance was evaluated with and without cognitive support for remembering (i.e., verbal cues). Under unsupported conditions, the mnemonic group improved number recall following training and the self-generated strategy group showed a tendency in the same direction. When support was provided, group differences in favor of the two training groups increased. In addition, no training-related gains were observed in two verbal transfer tasks. The relatively similar patterns of gains in the two intervention groups were discussed in terms of advantages and disadvantages in the two training regimens balancing each other.

Design your own memory strategies! Self-generated strategy training versus mnemonic training in old age: an 8-month follow-up.

We examined maintenance effects following training in a self-generated strategy versus a mnemonic strategy, designed to improve recall of four-digit numbers in older adults. This was accomplished by reassessing participants from a previous study eight months after completion of training. A control group that received no training was also included. The results showed that both training groups maintained training-related gains in number recall performance eight months later in a criterion task providing cognitive support. However, when no support was provided, number recall performance for the mnemonic group dropped slightly whereas performance for the self-generated strategy group improved. The control group maintained performance across assessments. These data indicate the numerical memory training may result in long-term effects in older adults and that, under some conditions, practising ones own memory strategies may have advantages over mnemonic training in old age.

Collaborative memory intervention in dementia: Caregiver participation matters

The aim of the study was to examine the effectiveness of a collaborative memory intervention for persons with dementia and their spousal caregivers, where the couple acquired and practised memory supportive strategies (spaced-retrieval and hierarchical cuing) to learn a face–name association and to set a table for coffee/tea. The collaborative intervention was compared to an individual intervention where the person with dementia received the same training but without the participating caregiver and to a control group of couples receiving no training. The results showed that following collaborative intervention recall performance in two collaborative tasks became more equally shared between the spouses, reflected in a decrease in recall for the caregiver and in an increase in recall for the spouse with dementia between pre- and post-test; whereas for the other two groups the caregivers dominated collaborative recall both at pre- and post-test. The results also showed that the persons with dementia in the collaborative group improved their individually assessed episodic memory performance as compared to the persons with dementia in the other two groups. Finally, training had no effects on episodic memory, perceived burden or depressive symptoms for the caregivers. These results suggest that the active participation of the caregiver matters in cognitive dementia rehabilitation.