The extent of working memory deficits associated with Williams syndrome: exploration of verbal and spatial domains and executively controlled processes

The present study investigated verbal and spatial working memory (WM) functioning in individuals with the neuro-developmental disorder Williams syndrome (WS) using WM component tasks. While there is strong evidence of WM impairments in WS, previous research has focused on short-term memory and has neglected assessment of executive components of WM. There is a particular lack of consensus concerning the profile of verbal WM functioning in WS. Here, WS participants were compared to typically developing participants matched for (1) verbal ability and (2) spatial ability (N = 14 in each of the 3 groups). Individuals with WS were impaired on verbal WM tasks, both those involving short-term maintenance of information and executive manipulation, in comparison to verbal-matched controls. Surprisingly, individuals with WS were not impaired on a spatial task assessing short-term maintenance of information in memory (remembering spatial locations) compared to spatial-matched controls. They were, however, impaired on a spatial executive WM task requiring the manipulation of spatial information in memory. The present study suggests that individuals with WS show WM impairments that extend to both verbal and spatial domains, although spatial deficits are selective to executive aspects of WM function.     

Executive function and psychosocial adjustment in healthy children and adolescents: A latent variable modelling investigation

The objective of this study was to establish latent executive function (EF) and psychosocial adjustment factor structure, to examine associations between EF and psychosocial adjustment, and to explore potential development differences in EF-psychosocial adjustment associations in healthy children and adolescents. Using data from the multisite National Institutes of Health (NIH) magnetic resonance imaging (MRI) Study of Normal Brain Development, the current investigation examined latent associations between theoretically and empirically derived EF factors and emotional and behavioral adjustment measures in a large, nationally representative sample of children and adolescents (7–18 years old; N = 352). Confirmatory factor analysis (CFA) was the primary method of data analysis. CFA results revealed that, in the whole sample, the proposed five-factor model (Working Memory, Shifting, Verbal Fluency, Externalizing, and Internalizing) provided a close fit to the data, χ²(66) = 114.48, p < .001; RMSEA = .046; NNFI = .973; CFI = .980. Significant negative associations were demonstrated between Externalizing and both Working Memory and Verbal Fluency (p < .01) factors. A series of increasingly restrictive tests led to the rejection of the hypothesis of invariance, thereby precluding formal statistical examination of age-related differences in latent EF-psychosocial adjustment associations. Findings indicate that childhood EF skills are best conceptualized as a constellation of interconnected yet distinguishable cognitive self-regulatory skills. Individual differences in certain domains of EF track meaningfully and in expected directions with emotional and behavioral adjustment indices. Externalizing behaviors, in particular, are associated with latent Working Memory and Verbal Fluency factors.     

Working Memory and Cognitive Skills in Individuals with Down Syndrome

This work is aimed at analyzing working memory (WM) components and their relationships with other cognitive processes in individuals with Down syndrome (DS). Particular attention is given to examine whether a verbal WM deficit is due to difficulties in verbal abilities often showed by individuals with DS, or whether it is a deficit per se. A group of 20 individuals with DS was compared to a group of 20 typically developing (TD) children matched on vocabulary comprehension and to a group of 20 TD children matched on general verbal intelligence. The groups received a battery of 3 verbal and 3 visuospatial WM tasks requiring different degrees of control, and tests assessing verbal abilities (WPPSI verbal scale, PPVT), nonverbal skills (WPPSI performance scale), and logical thinking (LO). The results revealed that individuals with DS have deficits in both central executive (control) and verbal components of the WM system, and the latter one is independent of the general verbal abilities deficit. The data suggest that the development of central executive proceeds at a slower rate in individuals with DS and differently from TD children with comparable verbal abilities. The performance of individuals with DS on high-control WM tasks requires additional general resources that are strictly linked to intelligence.     

Memory coding in individuals with Down syndrome

Previous research has identified a deficit in phonological short-term memory in individuals with Down syndrome.

The present work aimed to analyze how a group of 30 individuals with Down syndrome performed in a picture span task compared with 30 typically developing children of the same mental age. The task involved four conditions (i.e., dissimilar, phonologically similar, visually similar, and long-name items) chosen to analyze the strategy used by individuals with Down syndrome to code visually presented nameable items.

Individuals with Down syndrome performed less well than typically developing children. Both groups showed the visual similarity effect.

Taken together, our results confirm that individuals with Down syndrome have a verbal working memory deficit, even when nameable items are presented visually. Mental age appears to be an important determinant of memory coding stage in individuals with Down syndrome.     

Executive abilities in children with congenital visual impairment in mid-childhood

The role of vision and vision deprivation in the development of executive function (EF) abilities in childhood is little understood; aspects of EF such as initiative, attention orienting, inhibition, planning and performance monitoring are often measured through visual tasks. Studying the development and integrity of EF abilities in children with congenital visual impairment (VI) may provide important insights into the development of EF and also its possible relationship with vision and non-visual senses. The current study investigates non-visual EF abilities in 18 school-age children of average verbal intelligence with VI of differing levels of severity arising from congenital disorders affecting the eye, retina, or anterior optic nerve. Standard auditory neuropsychological assessments of sustained and divided attention, phonemic, semantic and switching verbal fluency, verbal working memory, and ratings of everyday executive abilities by parents were undertaken. Executive skills were compared to age-matched typically-sighted (TS) typically-developing children and across levels of vision (mild to moderate VI [MVI] or severe to profound VI [SPVI]). The results do not indicate significant differences or deficits on direct assessments of verbal and auditory EF between the groups. However, parent ratings suggest difficulties with everyday executive abilities, with the greatest difficulties in those with SPVI. The findings are discussed as possibly reflecting increased demands of behavioral executive skills for children with VI in everyday situations despite auditory and verbal EF abilities in the typical range for their age. These findings have potential implications for clinical and educational practices.     

The relationship between executive function and verbal memory in Parkinson's disease

A growing body of evidence suggests that the various cognitive symptoms found in Parkinson's disease (PD) are secondary to executive dysfunction. Studies addressing this possibility for memory impairment specifically have not included measures of working memory nor have they ruled-out potential mediating variables such as overall level of cognitive impairment or depression. The purpose of this study was to include measures of these variables in determining the relationship between multiple aspects of executive function and delayed verbal recall in 32 idiopathic PD patients. Results were consistent with the original hypothesis and further suggest that working memory is a key factor in recall memory and may mediate the relationship between other executive measures and recall in PD.     

Cognitive processes that underlie mathematical precociousness in young children

The working memory (WM) processes that underlie young children's (ages 6-8 years) mathematical precociousness were examined. A battery of tests that assessed components of WM (phonological loop, visual-spatial sketch pad, and central executive), naming speed, random generation, and fluency was administered to mathematically precocious and average-achieving children. The results showed that (a) precocious children performed better on executive processing, inhibition, and naming speed tasks than did average-achieving children, although the two groups were statistically comparable on measures of the phonological loop and visual-spatial sketch pad, and (b) the executive component of WM predicted mathematical accuracy independent of chronological age, reading, inhibition, and naming speed. The results support the notion that the executive system is an important predictor of children's mathematical precociousness and that this system can operate independent of individual differences in the phonological loop, inhibition, and reading in predicting mathematical accuracy.     

Morphological patterns in Hungarian children with Williams syndrome and the rule debates

Williams syndrome (WMS), a rare neurogenetic disorder, has been in the forefront of research in cognitive psychology for the last 10 years. Studies of grammatical development in 14 Hungarian WMS children are presented: they were examined on tasks testing regular and irregular morphology; measures of digit span were also obtained. Results on the production of accusative and plural forms confirmed for Hungarian that regardless of the frequency of the item, inflected forms of irregulars are harder to produce, and often regularized in WMS, revealing a dissociation between the rules of grammar vs. the mental lexicon. Overall performance on the morphology task is associated with the capacity of phonological short-term memory: subjects with higher span perform better on both tasks. The specification of the surprisingly close relation of phonological short-term memory with the linguistic measures awaits further study.     

The Association Between Health and Cognitive Performance in a Population-Based Study of Older Adults: The Charlotte County Healthy Aging Study (CCHAS)

In the present study, the relationship between self-reports and objective measures of health status and measures of cognitive performance was examined. Participants consisted of 437 persons (M =72.91 years) from the Charlotte County Healthy Aging Study, a population-based sample of older adults. Cognitive performance was assessed by tests of episodic memory, perceptual speed, and attention. Health status was indexed by subjective ratings, self-reports, and objective measures. The health measures accounted for significant variance on both the Trailmaking A and B tests, accounting for a modest amount of variance (4.4% and 1.1%, respectively). The health measures were not significantly associated with performance on the measures of attention or episodic memory. The results suggest that health status is associated with processing speed to a greater degree than higher order cognitive processes.     

Performance on the dimensional change card sort and backward digit span by young children with autism without intellectual disability

The early development of executive function (EF) and its relation to autism symptom expression is of considerable theoretical interest, particularly in children without general cognitive delay. Executive function was tested in 23 children with autism spectrum disorders (ASD) without intellectual disability and 20 age- and IQ-matched typically developing children. Even though performance was equivalent between the two groups on tests of general intelligence, flexibility in card sorting was lower for children with ASD. Verbal working memory during the backward digit span did not differ between groups. Among children with ASD, poorer performance on card sorting distinguished a subgroup with worse social-communication functioning above and beyond IQ. Controlling for IQ social and repetitive symptoms of ASD did not differ based on card sorting ability.     

Exercise mode and executive function in older adults: An ERP study of task-switching

The purpose of this study was to investigate the relationship between exercise mode and executive function and its effect on behavior and neuroelectric activity. Forty-eight older adults were classified into open-skill, closed-skill, and irregular exercise groups based on their experience of exercise participation. Executive function was measured via a task-switching paradigm, in which the behavioral indices and event-related potentials elicited by task-switching were assessed. The results revealed that the exercise groups, regardless of the exercise mode, exhibited faster reaction times in both global and local switches than the irregular exercise group, regardless of the within-task conditions. Similarly, larger P3 amplitudes were observed in both exercise groups compared to the irregular exercise group. Moreover, additional facilitation effects of open-skill exercises on global switch costs were observed, whereas no differences in local switch costs were found among the three groups. The results replicate previous studies that have reported generally improved executive function after participation in exercises; additionally, they extend the current knowledge by indicating that these cognitive improvements in specific aspects of executive function could also be obtained from open-skill exercises.     

Verbal fluency in children with ADHD: Strategy using and temporal properties

Verbal fluency tasks are commonly used in cognitive and developmental neuropsychology in assessing executive functions, language skills as well as divergent thinking. Twenty-two typically developing children and 22 children with ADHD between the ages of 8 and12 years were examined using verbal fluency tasks, prepotent response inhibition, and working memory tests. The clinical group showed impaired inhibitory and spatial working memory processes. We used different qualitative analyses of verbal fluency tasks to explore the lexical and executive strategies (word clustering and switching), and the temporal properties of the responses. Children with ADHD had a leeway in applying relevant lexical or executive strategies related to difficulties in strategy using. The reduced efficiency of children with ADHD in semantic fluency task is based on suboptimal shifting between word clusters and is related to the lack of ability of producing new clusters of items. The group difference appeared at the level of accessing and/or activating common words; however, the executive process of searching the lexicon extensively is intact.     

The differential contribution of executive functions to temporal generalisation,reproduction and verbal estimation

Evidence from dual-task studies suggests that executive resources are recruited during timing. However, there has been little exploration of whether executive recruitment is universal across temporal tasks, or whether different temporal tasks recruit different executive resources. The current study explored this further by examining how individual differences in updating, switching, inhibition and access affected performance on temporal generalisation, reproduction and verbal estimation tasks. It was found that temporal tasks differentially loaded onto different executive resources. Temporal generalisation performance was related to updating and access ability. Reproduction performance was related to updating, access and switching. Verbal estimation performance was only related to access. The results suggest that executive resources may be recruited when monitoring and maintaining multiple durations in memory at the same time, and when retrieving duration representations from long-term memory. The findings emphasise the need to consider timing behaviour as the product of a wide range of complex, integrated, cognitive systems, rather than as the output of a clock in isolation.     

Bilinguals who stutter: A cognitive perspective

PurposeBrain differences, both in structure and executive functioning, have been found in both developmental stuttering and bilingualism. However, the etiology of stuttering remains unknown. The early suggestion that stuttering is a result of brain dysfunction has since received support from various behavioral and neuroimaging studies that have revealed functional and structural brain changes in monolinguals who stutter (MWS). In addition, MWS appear to show deficits in executive control. However, there is a lack of data on bilinguals who stutter (BWS). This literature review is intended to provide an overview of both stuttering and bilingualism as well as synthesize areas of overlap among both lines of research and highlight knowledge gaps in the current literature.MethodsA systematic literature review on both stuttering and bilingualism studies was conducted, searching for articles containing “stuttering” and/or “bilingualism” and either “brain”, “executive functions”, “executive control”, “motor control”, “cognitive reserve”, or “brain reserve” in the PubMed database. Additional studies were found by examining the reference list of studies that met the inclusion criteria.ResultsA total of 148 references that met the criteria for inclusion in this paper were used in the review. A comparison of the impact of stuttering or bilingualism on the brain are discussed.ConclusionPrevious research examining a potential bilingual advantage for BWS is mixed. However, if such an advantage does exist, it appears to offset potential deficits in executive functioning that may be associated with stuttering.     

Investigating the childhood development of working memory using sentences: New evidence for the growth of chunk capacity

Child development is accompanied by a robust increase in immediate memory. This may be due to either an increase in the number of items (chunks) that can be maintained in working memory or an increase in the size of those chunks. We tested these hypotheses by presenting younger and older children (7 and 12 years of age) and adults with different types of lists of auditory sentences: four short sentences, eight short sentences, four long sentences, and four random word lists, each read with a sentence-like intonation. Young children accessed (recalled words from) fewer clauses than did older children or adults, but no age differences were found in the proportion of words recalled from accessed clauses. We argue that the developmental increase in memory span was due to a growing number of chunks present in working memory with little role of chunk size.     

Selective deficit in spatial location memory in extremely low birth weight children at age six: The PETIT Study

Spatial location memory has rarely been assessed in young children due to a scarcity of developmentally appropriate tests. This study sought to compare nonverbal learning and recall in children born extremely low birth weight (ELBW; <1000 g) and less than 33 gestational weeks (GW) with term-born children at early school age using a recently developed and adapted test. We administered a modification of the Hopkins Board to 210 children at age six; 84 born ELBW (35 born < 26 GW; 49 born 26–33 GW) and 126 term-born. Six measures were obtained: naming, trials-to-criterion, errors-to-criterion, delayed item recall, delayed location recall, and percent retention. After age correction, ELBW children had worse general cognition, item naming, delayed item recall, delayed location recall, and percent retention than term-born children. Delayed item recall and percent retention performances of ELBW children remained worse after correction for general cognition. ELBW groups (< 26 GW and 26–33 GW) groups performed worse than term-born children in naming and delayed item recall with chronological age as covariate. Those born before 26 GW, but not 26–33 GW, performed worse than term-born children in delayed location recall and percent retention. Differences remained significant after controlling for gender, maternal education, and delivery type. All three groups' performance declined from final learning trial to delayed location recall, with a decline greater for less than 26 GW than term-born children. Extreme prematurity (< 26 GW) and ELBW are significant risk factors for spatial location memory deficit. The modified Hopkins Board discriminated high-risk preterm and term-born children at early school age and appears to be a useful test to measure this rarely studied cognitive capacity.     

Implicit Learning of Affective Responses in Dementia Patients: A Face-Emotion-Association Paradigm

ABSTRACT

Young and older adults performed verbal and spatial storage-only and storage-plus-processing working memory tasks while performing a secondary finger tapping task, and the effects on both the maximum capacity (measured as the longest series correct) and the reliability (measured as the proportion of items correct) of working memory were assessed. Tapping tended to produce greater disruption of working memory tasks that place greater demands on executive processes (i.e., storage-plus-processing tasks compared to storage-only span tasks). Moreover, tapping produced domain-general interference, disrupting both verbal and spatial working memory, providing further support for the idea that tapping interferes with the executive component of the working memory system, rather than domain-specific maintenance processes. Nevertheless, tapping generally produced equivalent interference effects in young and older adults. Taken together, these findings are inconsistent with the hypothesis that age-related declines in working memory are primarily attributable to a deficit in the executive component.     

Intellectual growth in children as a function of domain specific and domain general working memory subgroups

This study examined whether children's growth on measures of fluid (Raven Colored Progressive Matrices) and crystallized (reading and math achievement) intelligence was attributable to domain-specific or domain-general functions of working memory (WM). A sample of 290 elementary school children was tested on measures of intelligence across three testing waves. Two methods, a hierarchical factor model predicting latent growth and a double dissociation design comparing children divided into high and low performers, tested whether general and/or specific components accounted for performance on intelligence measures. A general domain model for the total sample provided the best fit for latent growth on all measures. Further, the lack of a significant WM subgroup × domain interaction suggested that a general WM system underlies the individual differences on measures of fluid and crystallized intelligence. Overall, the findings support a domain-general view of WM capacity on intelligence measures in children, but also suggest that domain specific storage systems may come into play on isolated measures.     

Impaired Consonant Trigrams Test (CTT) performance relates to everyday working memory difficulties in children with Autism Spectrum Disorders

Individuals with Autism Spectrum Disorders (ASD) often struggle with complex tasks, such as those requiring divided attention (simultaneously completing two independent tasks) that also place high demands on working memory. Prior research shows that divided attention is impaired in adults and children with ASD and is related to ASD and comorbid attention deficit/hyperactivity disorder (ADHD) symptoms, but the impact on everyday functioning is unclear. Because ADHD symptoms are associated with poor divided attention and working memory performance in children with ASD, we also examined ADHD symptoms as moderators of divided attention performance. We examined performance on the Consonant Trigrams Test (CTT) between high-functioning 8- to 13-year-olds with ASD (n?=?28) and typically developing controls (n?=?18) matched on age and IQ. In the ASD group, we also correlated performance with ADHD symptoms and behavior ratings of everyday working memory. CTT performance in children with ASD was significantly worse than in matched controls. A significant correlation between CTT performance and everyday working memory was observed, but CTT performance was not related to comorbid ADHD symptoms in the ASD group. Divided attention with high working-memory demands is a relative weakness in children with high-functioning ASD; this weakness relates to everyday functioning, and it is independent from ADHD symptoms. That ADHD symptoms are not associated with divided attention performance is inconsistent with one prior investigation, which likely results from using different divided attention tasks in the two studies.