A cross-sectional study on interference control: age affects reactive control but not proactive control

Background

Working memory updating (WMU), a controlled process to continuously adapt to the changing task demand and environment, is crucial for cognitive executive function. Although previous studies have shown that the elderly were more susceptible to cognitive interference than the youngsters, the picture of age-related deterioration of WMU is incomplete due to lack of study on people at their middle ages. Thus, the present study investigated the impact of age on the WMU among adults by a cross-sectional design to verify whether inefficiency interference control accounts for the aging of WMU.

Methods

In total, 112 healthy adults were recruited for this study; 28 old adults (21 female) ranging from 60 to 78 years of age; 28 middle-age adults (25 female) ranging from 45 to 59 years of age; 28 adults (11 female) ranging from 26 to 44 years of age; and 28 young adults (26 female) ranging from 18 to 25 years of age. Each participant completed a 1-back task. The inverse efficiency score was calculated in various sequences of three trials in a row to quantify the performance of WMU for adults of various ages.

Results

Inverse efficiency score of both young groups (young adult and adult) were significantly shorter than the old group in both Repeat-Alternate (RA, including □□○ and ○○□) and Alternate-Alternate (AA, including ○□○ and □○□) sequential patterns and they were additionally better than the middle-age group in AA sequential pattern.

Conclusion

With the increase of difficulty in the task, the difference in reactive interference control between young and middle age was gradually revealed, while the difference between young and old remained to apparent. The degradation of WMU aging may begin from middle-age and presents selective impairment in that only reactive interference control, but not proactive interference control, shows pronounced age-related decline. The preliminary results can inform future studies to further explore the whole lifespan trajectories of cognitive functions.

Magnitude Representation and Working Memory Updating in Children With Arithmetic and Reading Comprehension Disabilities

It has been argued that children with learning disabilities (LD) encounter severe problems in working memory (WM) tasks, especially when they need to update information stored in their WM. It is not clear, however, to what extent this is due to a generally poor updating ability or to a difficulty specific to the domain to be processed. To examine this issue, two groups of children with arithmetic or reading comprehension LD and a group of typically developing children (9 to 10 years old) were assessed using two updating tasks requiring to select the smallest numbers or objects presented. The results showed that children with an arithmetic disability failed in a number updating task, but not in the object updating task. The opposite was true for the group with poor reading comprehension, whose performance was worse in the object than in the number updating task. It may be concluded that the problem of WM updating in children with LD is also due to a poor representation of the material to be updated. In addition, our findings suggest that the mental representation of the size of objects relates to the semantic representation of the objects' properties and differs from the quantitative representation of numbers.

Age differences in working memory updating: the role of interference, focus switching and substituting information

Working memory updating (WMU) tasks require different elements in working memory (WM) to be maintained simultaneously, accessing one of these elements, and substituting its content. This study examined possible developmental changes from childhood to adulthood both in focus switching and substituting information in WM. In addition, possible age-related changes in interference due to representational overlap between the different elements simultaneously held in these tasks were examined. Children (8- and 11-year-olds), adolescents (14-year-olds) and younger adults (mean age=22 years) were administered a numerical updating memory task, in which updating and focus switching were manipulated. As expected, response times decreased and recall performance increased with age. More importantly, the time needed for focus switching was longer in children than in adolescents and younger adults. On the other hand, substitution of information and interference due to representational overlap were not affected by age. These results suggest that age-related changes in focus switching might mediate developmental changes in WMU performance.

The Role of Similarity in Updating Numerical Information in Working Memory: Decomposing the Numerical Distance Effect

The present study investigates the process of updating representations in working memory (WM) and how similarity between the information involved influences this process. In WM updating tasks, the similarity in terms of numerical distance between the number to be substituted and the new one facilitates the updating process. We aimed to disentangle the possible effect of two dimensions of similarity that may contribute to this numerical effect: numerical distance itself and common digits shared between the numbers involved. Three experiments were conducted in which different ranges of distances and the coincidence between the digits of the two numbers involved in updating were manipulated. Results showed that the two dimensions of similarity had an effect on updating times. The greater the similarity between the information maintained in memory and the new information that substituted it, the faster the updating. This is consistent both with the idea of distributed representations based on features, and with a selective updating process based on a feature overwriting mechanism. Thus, updating in WM can be understood as a selective substitution process influenced by similarity in which only certain parts of the representation stored in memory are changed.

Working memory retrieval differences between medial temporal lobe epilepsy patients and controls: a three memory layer approach

Multi-store models of working memory (WM) have given way to more dynamic approaches that conceive WM as an activated subset of long-term memory (LTM). The resulting framework considers that memory representations are governed by a hierarchy of accessibility. The activated part of LTM holds representations in a heightened state of activation, some of which can reach a state of immediate accessibility according to task demands. Recent neuroimaging studies have studied the neural basis of retrieval information with different states of accessibility. It was found that the medial temporal lobe (MTL) was involved in retrieving information within immediate access store and outside this privileged zone. In the current study we further explored the contribution of MTL to WM retrieval by analyzing the consequences of MTL damage to this process considering the state of accessibility of memory representations. The performance of a group of epilepsy patients with left hippocampal sclerosis in a 12-item recognition task was compared with that of a healthy control group. We adopted an embedded model of WM that distinguishes three components: the activated LTM, the region of direct access, and a single-item focus of attention. Groups did not differ when retrieving information from single-item focus, but patients were less accurate retrieving information outside focal attention, either items from LTM or items expected to be in the WM range. Analyses focused on items held in the direct access buffer showed that consequences of MTL damage were modulated by the level of accessibility of memory representations, producing a reduced capacity.