Superior Working Memory Research Articles

The contribution of interference control for young children`s working memory performance: Insights from eye-tracking

In the present study, the role of visual attentional processes for working memory performance in a sample of 6-year-olds was investigated. This was done by combining an individual differences approach with an experimental manipulation: For the individual differences approach, participants were grouped based on their performance in a classical interference control task, and their working memory skills were systematically compared. For the experimental manipulation, the need to control interference while performing a working memory task was increased in one condition through presentation of distracting stimuli. In a between-subject design performance in this condition was contrasted with a control condition without distractors. Additionally, fixation time during stimuli presentation were quantified by tracking participants` gazes. Results revealed that children with higher interference control skills showed superior working memory performance. Increasing the need to inhibit attention towards task-irrelevant information through presentation of distractors decreased working memory performance. The present study offers supporting evidence for a close relationship between young children`s working memory and attention.

Spontaneous strategy use protects against visual working memory deficits in older adults infected with HIV.

Recent studies suggest that older human immunodeficiency virus (HIV)-infected adults are at particular risk for HIV-associated neurocognitive disorders (HAND), including dementia. Deficits in attention/working memory are posited to play a central role in the development of HAND among older adults. The aim of the present study was to examine the possible protective benefits of spontaneous strategy use during a visual working memory task in 46 older and 42 younger adults infected with HIV. Results revealed a significant interaction between age and strategy use, with older adults who used a meta-cognitive strategy demonstrating superior working memory performance versus non-strategy users. This effect was not observed in the younger HIV-infected sample and was not better explained by possible confounding factors, such as education, comorbid medical conditions, or HIV disease severity. Within the older group, strategy use was associated with better executive functions and higher estimated verbal intelligence. Findings from this study suggest that working memory declines in older HIV-infected adults are moderated by the use of higher-level mnemonic strategies and may inform cognitive neurorehabilitation efforts to improve cognitive and everyday functioning outcomes in older persons living with HIV infection.

Cognitive Control in Auditory Working Memory Is Enhanced in Musicians

Musical competence may confer cognitive advantages that extend beyond processing of familiar musical sounds. Behavioural evidence indicates a general enhancement of both working memory and attention in musicians. It is possible that musicians, due to their training, are better able to maintain focus on task-relevant stimuli, a skill which is crucial to working memory. We measured the blood oxygenation-level dependent (BOLD) activation signal in musicians and non-musicians during working memory of musical sounds to determine the relation among performance, musical competence and generally enhanced cognition. All participants easily distinguished the stimuli. We tested the hypothesis that musicians nonetheless would perform better, and that differential brain activity would mainly be present in cortical areas involved in cognitive control such as the lateral prefrontal cortex. The musicians performed better as reflected in reaction times and error rates. Musicians also had larger BOLD responses than non-musicians in neuronal networks that sustain attention and cognitive control, including regions of the lateral prefrontal cortex, lateral parietal cortex, insula, and putamen in the right hemisphere, and bilaterally in the posterior dorsal prefrontal cortex and anterior cingulate gyrus. The relationship between the task performance and the magnitude of the BOLD response was more positive in musicians than in non-musicians, particularly during the most difficult working memory task. The results confirm previous findings that neural activity increases during enhanced working memory performance. The results also suggest that superior working memory task performance in musicians rely on an enhanced ability to exert sustained cognitive control. This cognitive benefit in musicians may be a consequence of focused musical training.

A slice of π : An exploratory neuroimaging study of digit encoding and retrieval in a superior memorist

Subject PI demonstrated superior memory using a variant of a Method of Loci (MOL) technique to recite the first digits of the mathematical constant π to more than 216 decimal places. We report preliminary behavioral, functional magnetic resonance imaging (fMRI), and brain volumetric data from PI. fMRI data collected while PI recited the first 540 digits of π (i.e., during retrieval) revealed increased activity in medial frontal gyrus and dorsolateral prefrontal cortex. Encoding of a novel string of 100 random digits activated motor association areas, midline frontal regions, and visual association areas. Volumetric analyses indicated an increased volume of the right subgenual cingulate, a brain region implicated in emotion, mentalizing, and autonomic arousal. Wechsler Abbreviated Scale of Intelligence (WASI) testing indicated that PI is of average intelligence, and performance on mirror tracing, rotor pursuit, and the Silverman and Eals Location Memory Task revealed normal procedural and implicit memory. PI's performance on the Wechsler Memory Scale (WMS-III) revealed average general memory abilities (50th percentile), but superior working memory abilities (99th percentile). Surprisingly, PI's visual memory (WMS-III) for neutral faces and common events was remarkably poor (3rd percentile). PI's self-report indicates that imagining affective situations and high emotional content is critical for successful recall. We speculate that PI's reduced memory for neutral/non-emotional faces and common events, and the observed increase in volume of the right subgenual cingulate, may be related to extensive practice with memorizing highly emotional material.

Caffeine Reverses Cognitive Impairment and Decreases Brain Amyloid-β Levels in Aged Alzheimer's Disease Mice

We have recently shown that Alzheimer's disease (AD) transgenic mice given a moderate level of caffeine intake (the human equivalent of 5 cups of coffee per day) are protected from development of otherwise certain cognitive impairment and have decreased hippocampal amyloid-beta (Abeta) levels due to suppression of both beta-secretase (BACE1) and presenilin 1 (PS1)/gamma-secretase expression. To determine if caffeine intake can have beneficial effects in "aged" APPsw mice already demonstrating cognitive impairment, we administered caffeine in the drinking water of 18-19 month old APPsw mice that were impaired in working memory. At 4-5 weeks into caffeine treatment, those impaired transgenic mice given caffeine (Tg/Caff) exhibited vastly superior working memory compared to the continuing impairment of control transgenic mice. In addition, Tg/Caff mice had substantially reduced Abeta deposition in hippocampus (decrease 40%) and entorhinal cortex (decrease 46%), as well as correlated decreases in brain soluble Abeta levels. Mechanistically, evidence is provided that caffeine suppression of BACE1 involves the cRaf-1/NFkappaB pathway. We also determined that caffeine concentrations within human physiological range effectively reduce active and total glycogen synthase kinase 3 levels in SweAPP N2a cells. Even with pre-existing and substantial Abeta burden, aged APPsw mice exhibited memory restoration and reversal of AD pathology, suggesting a treatment potential of caffeine in cases of established AD.

In first presentation adolescent anorexia nervosa, do cognitive markers of underweight status change with weight gain following a refeeding intervention?

To determine the nature and severity of cognitive functioning impairment in adolescent anorexia nervosa (AN) when underweight and following weight gain. In 37 first admission adolescent (12-18 years) AN patients and 45 matched controls, general cognitive functions were assessed at baseline and follow-up using the IntegNeuro-computerized battery. AN participants were tested between days 3 and 10 of their admission when underweight, with retesting conducted after weight restoration. When underweight, AN participants performed more poorly than controls on sensori-motor speed tasks and exhibited a susceptibility to interference, but had superior working memory. Once the weight is restored, individuals significantly improved relative to their own performance. Relative to controls, they were significantly faster on attention and executive function tasks, exhibited superior verbal fluency, working memory, and a significantly superior ability to inhibit well-learnt responses. Cognitive impairments in adolescent AN appear to normalize with refeeding and weight gain.

Individual differences in the ability to avoid distracting sounds

The present work aims to establish a greater understanding of the cognitive mechanisms involved in avoiding distraction from speech and nonspeech sounds. Although mixed results have been presented by research investigating the hypothesis that individuals with superior working memory abilities are better able to avoid acoustic distraction, we found that working memory correlated with some aspects of performance during distraction when carefully examined. This is consistent with the view that working memory involves resisting interference. In a large sample, we examined two different tasks accompanied by acoustic distraction—serial recall and rapid colour naming—as well as two different measures of working memory (operation span and running span). We show that the previous inability to find relations between working memory and avoidance of distraction may stem from the use of inadequate correlational techniques. Additionally, the level of difficulty of the serial recall task may be an important factor. The results illustrate that commonly used statistical techniques can be misleading and furthermore that the ability to avoid distraction from irrelevant items may not be a unitary construct.

Bottom-Up Driven Speechreading in a Speechreading Expert: The Case of AA (JK023)

This case study tested the threshold hypothesis (Rönnberg et al., 1998), which states that superior speechreading skill is possible only if high-order cognitive functions, such as capacious verbal working memory, enable efficient strategies. In a case study, a speechreading expert (AA) was tested on a number of speechreading and cognitive tasks and compared with control groups (z scores). Sentence-based speechreading tests, a word-decoding test, and a phoneme identification task were used to assess speechreading skill at different analytical levels. The cognitive test battery used included tasks of working memory (e.g., reading span), inference-making, phonological processing (e.g., rhyme-judgment), and central-executive functions (verbal fluency, Stroop task). Contrary to previous cases of extreme speechreading skill, AA excels on both low-order (phoneme identification: z = +2.83) and high-order (sentence-based: z = +8.12 and word-decoding: z = +4.21) speechreading tasks. AA does not display superior verbal inference-making ability (sentence-completion task: z = -0.36). Neither does he possess a superior working memory (reading span: z = +0.80). However, AA outperforms the controls on two measures of executive retrieval functions, the semantic (z = +3.77) and phonological verbal fluency tasks (z = +3.55). The performance profile is inconsistent with the threshold hypothesis. Extreme speechreading accuracy can be obtained in ways other than via well-developed high-order cognitive functions. It is suggested that AA's extreme speechreading skill, which capitalizes on low-order functions in combination with efficient central executive functions, is due to early onset of hearing impairment.

The concurrent validity and test–retest reliability of a visuospatial working memory task

To determine whether the visuospatial n-back working memory task is a reliable and valid measure of cognitive processes believed to underlie intelligence, this study compared the reaction times and accuracy of performance of 70 participants, with performance on the Multidimensional Aptitude Battery (MAB). Testing was conducted over two sessions separated by 1 week. Participants completed the MAB during the second test session. Moderate test–retest reliability for percentage accuracy scores was found across the four levels of the n-back task, whilst reaction times were highly reliable. Furthermore, participants' performance on the MAB was negatively correlated with accuracy of performance at the easier levels of the n-back task and positively correlated with accuracy of performance at the harder task levels. These findings confirm previous research examining the cognitive basis of intelligence, and suggest that intelligence is the product of faster speed of information processing, as well as superior working memory capacity.

Resilient readers? University students who are poor recoders but sometimes good text comprehenders.

The authors screened 194 university students to determine whether some could comprehend text well despite very poor recoding skills, measured by pseudoword reading. Most of the 17 poorest recoders had never been identified as reading disabled. We classified 6 poor recoders as resilient readers because their text comprehension scores were average or above, relative to the sample as a whole. They were indistinguishable from 6 matched typical readers on measures of text comprehension derived from oral-reading think-aloud protocols. There was no evidence that the resilient readers relied on superior verbal ability or working memory to compensate for poor recoding. The resilient readers were poor at spelling, reading isolated words, and reading text rapidly, but they showed adequate phonemic awareness.

In two species, females exhibit superior working memory and inferior reference memory on the water radial-arm maze

Male and female mice and rats were tested on a water escape version of the radial-arm maze designed to measure working and reference memory. In both species, females exhibited superior working memory during acquisition, and were better able to handle a higher memory load. However, male mice and rats exhibited better reference memory than females during the asymptotic portion of testing. Our data suggest that females may be better at working memory when both working and reference memory information must be learned simultaneously, and males better at reference memory when it has been differentiated from working memory.

The association of elaborative or maintenance rehearsal with age, reading comprehension, and verbal working memory performance

Elaborative or maintenance rehearsal strategy-use during a verbal working memory task was the grouping variable for a study that tested whether group membership distinguished 53 healthy adults by age, education, or performance on reading comprehension and verbal working memory tasks. No significant differences in age or reading comprehension emerged as a function of strategy-use. However, the elaborative strategy group had significantly better performance on one measure of verbal working memory. Several within age-group differences as a function of strategy-use were also significant. Younger adults who used elaborative rehearsal had superior working memory measures, and older adults who used elaborative rehearsal had superior reading comprehension measures, suggesting elaborative rehearsal's memory-enhancing function in verbal working memory and reading comprehension tasks.