Phonological Loop Research Articles

Is the frontal dysexecutive syndrome due to a working memory deficit? Evidence from patients with stroke

Although frontal dysexecutive disorders are frequently considered to be due to working memory deficit, this has not been systematically examined and very little evidence is available for impairment of working memory in frontal damage. The objective of this study was to examine the components of working memory, their anatomy and the relations with executive functions in patients with stroke involving the frontal or posterior cortex. The study population consisted of 29 patients (frontal: n=17; posterior: n=12) and 29 matched controls. Phonological loop (letter and word spans, phonological store; rehearsal process), visuospatial sketchpad (visuospatial span) and the central executive (working memory span, dual task and updating process) were examined. The group comparison analysis showed impairment in the frontal group of: (i) verbal spans (P<0.03); (ii) with a deficit of the rehearsal process (P=0.006); (iii) visuospatial span (P=0.04); (iv) working memory span (P=0.001) that disappeared after controlling for verbal span and (v) running memory (P=0.05) unrelated to updating conditions. The clinical anatomical correlation study showed that impairment of the central executive depended on frontal and posterior lesion. Cognitive dysexecutive disorders were observed in 11/20 patients with central executive deficit and an inverse dissociation was observed in two patients. Receiver operating characteristic curve analysis indicated that cognitive dysexecutive disorders had the highest ability to discriminate frontal lesions (area under curve=0.844, 95% confidence interval: 0.74-0.95; P=0.0001; central executive impairment: area under curve=0.732, 95% confidence interval: 0.57-0.82; P=0.006). This study reveals that frontal lesions induce mild impairment of short-term memory associated with a deficit of the rehearsal process supporting the role of the frontal lobe in this process; the central executive depends on lesions in the frontal lobe and posterior regions accounting for its low frequency and the negative results of group studies. Finally, the frontal dysexecutive syndrome cannot be attributed to central executive impairment, although it may contribute to some dysexecutive disorders.

Involvement of the cerebellar cortex and nuclei in verbal and visuospatial working memory: A 7T fMRI study

The first aim of the present study was to extend previous findings of similar cerebellar cortical areas being involved in verbal and spatial n-back working memory to the level of the cerebellar nuclei. The second aim was to investigate whether different areas of the cerebellar cortex and nuclei contribute to different working memory tasks (n-back vs. Sternberg tasks). Young and healthy subjects participated in two functional magnetic resonance imaging (fMRI) studies using a 7 T MR scanner with its increased signal-to-noise ratio. One group of subjects (n=21) performed an abstract and a verbal version of an n-back task contrasting a 2-back and 0-back condition. Another group of subjects (n=23) performed an abstract and a verbal version of a Sternberg task contrasting a high load and a low load condition. A block design was used. For image processing of the dentate nuclei, a recently developed region of interest (ROI) driven normalization method of the dentate nuclei was applied (Diedrichsen et al., 2011). Whereas activated areas of the cerebellar cortex and dentate nuclei were not significantly different comparing the abstract and verbal versions of the n-back task, activation in the abstract and verbal Sternberg tasks was significantly different. In both n-back tasks activation was most prominent at the border of lobules VI and Crus I, within lobule VII, and within the more caudal parts of the dentate nucleus bilaterally. In Sternberg tasks the most prominent activations were found in lobule VI extending into Crus I on the right. In the verbal Sternberg task activation was significantly larger within right lobule VI compared to the abstract Sternberg task and compared to the verbal n-back task. Activations of rostral parts of the dentate were most prominent in the verbal Sternberg task, whereas activation of caudal parts predominated in the abstract Sternberg task. On the one hand, the lack of difference between abstract and verbal n-back tasks and the lack of significant lateralization suggest a more general contribution of the cerebellum to working memory regardless of the modality. On the other hand, the focus of activation in right lobule VI in the verbal Sternberg task suggests specific cerebellar contributions to verbal working memory. The verbal Sternberg task emphasizes maintenance of stimuli via phonological rehearsal, whereas central executive demands prevail in n-back tasks. Based on the model of working memory by Baddeley and Hitch (1974), the present results show that different regions of the cerebellum support functions of the central executive system and one of the subsidiary systems, the phonological loop.

Maintaining information online in discrete time; rethinking working memory processes

Linguistic operations occur with verbal information maintained online for a discrete time. It is posited that online maintenance of information is accomplished by verbal working memory (WM), a system that is: (a) independent from the linguistic operations carried out with the information (specialized), and (b) consists of a holding place where information is held in a phonological code (phonological loop) and a rehearsal mechanism that refreshes the phonological loop. This model does not account for the serial position effects associated with information maintenance and additional models are needed to explain the latter effects, which leaves us with a disjointed understanding of online maintenance of information.In this study, 36 middle-aged, healthy subjects (33 males and 3 females) were required to maintain linguistic information (letters) online. The letters called upon different cognitive operations (orthographic; orthographic and phonetic; or orthographic, phonetic and semantic). It was found that online maintenance capacity depends on the cognitive operations associated with the letters and on their serial position. Additionally, the cognitive operation effect on online maintenance was modulated by the serial position.These data favor a model for WM consisting of a simple holding place where verbal information maintenance depends on what the information is used for. We will discuss an integrated model for online information maintenance that accounts for the serial position effects.

Children With Specific Language Impairment and Resolved Late Talkers: Working Memory Profiles at 5 Years

The evidence of a deficit in working memory in specific language impairment (SLI) is of sufficient magnitude to suggest a primary role in developmental language disorder. However, little research has investigated memory in late talkers who recover from their early delay. Drawing on a longitudinal, community sample, this study compared the memory profiles of 3 groups of 5-year-olds: children with SLI who had been identified as late talkers, resolved late talkers (RLTs), and children with typical language development (TLD). Participants were 25 children with SLI, 45 RLTs, and 32 children with TLD. Subtests from the Working Memory Test Battery for Children and the Children's Memory Scale plus recalling sentences and nonword repetition tasks were administered to test the components of Baddeley's working memory model. The SLI group showed significantly poorer performance than the RLT and TLD groups on measures of the phonological loop and episodic buffer. The RLT and TLD groups scored similarly on all memory measures. The results support previous findings that sentence recall and nonword repetition are markers of SLI. Although residual effects of late-talking status may emerge over time, RLTs do not necessarily show memory deficits at 5 years of age despite delayed early vocabulary development.

The irrelevant sound effect under articulatory suppression is a suffix effect even with five-item lists

The relationship between the suffix effect and the effect of irrelevant sound on serial recall of auditorily presented lists is investigated in this study. Contrary to the predictions of the phonological loop model, Hanley and Hayes (2012) reported that the irrelevant sound effect was abolished under articulatory suppression when a spoken suffix was added at the end of the list. The experiment reported in this paper uses a shorter list length (five items per list) than that employed by Hanley and Hayes. This is because it cannot realistically be argued that participants will abandon the use of phonological codes to retain the list items with sequences as short as this. Results replicated those of Hanley and Hayes (2012). There was a significant effect of irrelevant sound under articulatory suppression when the list items were followed by an auditory tone. Crucially, however, the effect of irrelevant sound under articulatory suppression was abolished when the list items were followed by a spoken suffix.

Working memory for speech and music

The present paper reviews behavioral and neuroimaging findings on similarities and differences between verbal and tonal working memory (WM), the influence of musical training, and the effect of strategy use on WM for tones. Whereas several studies demonstrate an overlap of core structures (Broca's area, premotor cortex, inferior parietal lobule), preliminary findings are discussed that imply, if confirmed, the existence of a tonal and a phonological loop in musicians. This conclusion is based on the findings of partly differing neural networks underlying verbal and tonal WM in musicians, suggesting that functional plasticity has been induced by musical training. We further propose a strong link between production and auditory WM: data indicate that both verbal and tonal auditory WM are based on the knowledge of how to produce the to-be-remembered sounds and, therefore, that sensorimotor representations are involved in the temporary maintenance of auditory information in WM.

Use of a clay modeling task to reduce chocolate craving

Elaborated Intrusion theory (EI theory; Kavanagh, Andrade, & May, 2005) posits two main cognitive components in craving: associative processes that lead to intrusive thoughts about the craved substance or activity, and elaborative processes supporting mental imagery of the substance or activity. We used a novel visuospatial task to test the hypothesis that visual imagery plays a key role in craving. Experiment 1 showed that spending 10min constructing shapes from modeling clay (plasticine) reduced participants’ craving for chocolate compared with spending 10min ‘letting your mind wander’. Increasing the load on verbal working memory using a mental arithmetic task (counting backwards by threes) did not reduce craving further. Experiment 2 compared effects on craving of a simpler verbal task (counting by ones) and clay modeling. Clay modeling reduced overall craving strength and strength of craving imagery, and reduced the frequency of thoughts about chocolate. The results are consistent with EI theory, showing that craving is reduced by loading the visuospatial sketchpad of working memory but not by loading the phonological loop. Clay modeling might be a useful self-help tool to help manage craving for chocolate, snacks and other foods.

Does working memory change with age? The interactions of concurrent articulation with the effects of word length and acoustic confusion

ABSTRACT The effects of acoustic confusion (phonological similarity), word length, and concurrent articulation (articulatory suppression) are cited as support for Working Memory's phonological loop component (e.g., Baddeley, 2000, Psychonomic Bulletin and Review, 7, 544). Research has focused on younger adults, with no studies examining whether concurrent articulation reduces the word length and acoustic confusion effects among older adults. In the current study, younger and older adults were given lists of similar and dissimilar letters (Experiment 1) or long and short words (Experiment 2) for immediate serial reconstruction of order. Items were presented visually or auditorily, with or without concurrent articulation. As expected, younger and older adults demonstrated effects of acoustic confusion, word length, and concurrent articulation. Further, concurrent articulation reduced the effects of acoustic confusion and word length equally for younger and older adults. This suggests that age-related differences occur in overall performance, but do not reflect an age-related deficiency in the functioning of the phonological loop component of working memory.

The Neuronal Correlates of Digits Backward Are Revealed by Voxel-Based Morphometry and Resting-State Functional Connectivity Analyses

Digits backward (DB) is a widely used neuropsychological measure that is believed to be a simple and effective index of the capacity of the verbal working memory. However, its neural correlates remain elusive. The aim of this study is to investigate the neural correlates of DB in 299 healthy young adults by combining voxel-based morphometry (VBM) and resting-state functional connectivity (rsFC) analyses. The VBM analysis showed positive correlations between the DB scores and the gray matter volumes in the right anterior superior temporal gyrus (STG), the right posterior STG, the left inferior frontal gyrus and the left Rolandic operculum, which are four critical areas in the auditory phonological loop of the verbal working memory. Voxel-based correlation analysis was then performed between the positive rsFCs of these four clusters and the DB scores. We found that the DB scores were positively correlated with the rsFCs within the salience network (SN), that is, between the right anterior STG, the dorsal anterior cingulate cortex and the right fronto-insular cortex. We also found that the DB scores were negatively correlated with the rsFC within an anti-correlation network of the SN, between the right posterior STG and the left posterior insula. Our findings suggest that DB performance is related to the structural and functional organizations of the brain areas that are involved in the auditory phonological loop and the SN.

Literacy: Exploring working memory systems

Previous research showed an important association between reading and writing skills (literacy) and the phonological loop. However, the effects of literacy on other working memory components remain unclear. In this study, we investigated performance of illiterate subjects and their matched literate controls on verbal and nonverbal working memory tasks. Results revealed that the phonological loop is significantly influenced by literacy, while the visuospatial sketchpad appears to be less affected or not at all. Results also suggest that the central executive might be influenced by literacy, possibly as an expression of cognitive reserve.

Estructura de la memoria operativa: comparando diferentes modelos en la infancia

Working Memory (WM) is an active memory system responsible for the temporary storage and concurrent processing of information. Different authors have considered WM as a complex but unitary system, whereas others have suggested that the system is multidimensional. In this line, the model developed by Baddeley and Hitch (1974) is one of the most well known; it proposes two modality-specific components - the phonological loop and the visuo-spatial sketch pad - and a supervisory executive system - the central executive. This paper contributes to the debate on WM structure by investigating three groups of children of different ages and assessing different models using confirmatory factor analysis. The Working Memory Assessment Battery Test (Alloway, 2007; Injoque-Ricle, Calero, Alloway & Burin, 2011) was administered to 180 monolingual Spanish-speaking children. The three age groups consisted of 6-, 8-, and 11-year-old children (n = 60 participants per group). The results suggest that the WM structure is not uniform across the different age groups tested, showing progressive differentiation and specialization during childhood. This structure would appear to form between the ages of 6 and 8 years and become more complex as adolescence is approached.

Study of predictive validation for Working Memory Battery

Working Memory Battery (WMB) operationalizes the concept of working memory of Baddeley and Hitch, consisting of three components: phonological loop, visuo-spatial sketchpad and central executive. We hypothesized the existence of a significant correlation of WM with achievement in reading, writing and counting in primary school cycle. The battery will make the difference between masculine gender and feminine gender, between early ages and late ages of the cycle. We used Clinciu Working Memory Battery, consisting of five subtests. WMB is a good expression of working memory, showing a close connection to the criterion of academic achievement in the first school cycle.

Changes in Effective Connectivity According to Working Memory Load: An fMRI Study of Face and Location Working Memory Tasks

ObjectiveThe functional strategic mechanisms in the brain during performing visuospatial working memory tasks, especially tasks with heavy load, are controversial. We conducted the functional magnetic resonance imaging (fMRI) while sixteen subjects were performing face- and location-matching n-back tasks to examine causal relations within the frontoparietal networks.MethodsWe applied a sophisticated method, the structural equation modeling (SEM), to the fMRI data. The imaging data were analyzed by extracting the task-related eigenseries using the principal component analysis (PCA) and then by applying a form of data-driven model called the automated search method.ResultsThe SEM analyses revealed a functional shift of network connectivity from the right to the left hemisphere with increasing load in the face-matching n-back tasks while the location-matching tasks required bilateral activation. In the locating matching n-back tasks, a pattern of parallel processing was observed in the left phonological loop and the right inferior parietal regions. Furthermore, object working memory-related activities in the left hemisphere reliably contributed to performance of both the face- and location-matching 2-back tasks.ConclusionOur results are consistent with previous reports in terms of demonstrating parallel and distributed information processing during performing working memory tasks with heavy loads. Our results additionally suggest a dynamic shift between the fast imagery circuit (right hemisphere) and the stable verbal circuit (left hemisphere), depending on task load.

P-375 - Assessing trait anxiety impacts on effective performance and processing efficiency of working memory

In this study we assessed the effects of Gray's description of trait anxiety on effective performance and processing efficiency of working memory. To do so, a sample of female students (n = 793) performed Eysenck Personality Questionnaire and Carver and White's Approach/Avoidance scale. 15 subjects whose scores were simultaneously in the upper distribution of Neuroticism and lower distribution of Extraversion (N+E-) were selected as high trait anxiety group (Anx+) and low trait anxiety group (Anx-), consisted of 15 subjects with higher scores of Extraversion and lower scores of Neuroticism (N-E+).Then they performed working memory tasks package involved 1-back, Paced Auditory Serial Adding Test(PASAT), forward and backward Digit Span. Total scores in each task were taken as the indicator of effectiveness of performance and reaction times in 1-back were taken as the indicator of neural effort which shows the processing efficiency. Data were analyzed using T-test for independent samples. Results revealed that high trait anxiety subjects’ working memory were impaired both in effective performance and processing efficiency of central executive system, but phonological loop performance was not impaired significantly. Results supported Processing Efficiency Theory.

The anterior superior parietal lobule and its interactions with language and motor areas during writing

Past neuroimaging studies of writing demonstrate activation foci in several regions of the posterior parietal cortex (PPC). The present study aimed to dissociate the role of the superior parietal lobule (SPL) from the other PPC regions using functional magnetic resonance imaging (fMRI) and functional connectivity. First, parametric event-related fMRI permitted the categorical comparison of experimental writing conditions with control conditions that were carefully chosen to match the experimental conditions in terms of variables extraneous to the motor act of writing, such as visual stimulus characteristics, and generating and retrieving verbal information. A selective focus of increased activation in the PPC restricted to the rostral part of the SPL (area PE) in the left hemisphere was demonstrated. Subsequently, functional connectivity analysis showed that area PE flexibly interacts with different language areas depending on the linguistic demands of the writing task. Activity in area PE correlates with the left angular gyrus, a region implicated in reading, when the writing is in response to words that are read; in sharp contrast, when the writing is in response to pictured objects, then area PE correlates with the supramarginal gyrus, a region involved in the articulatory and phonological loop, as well as with prefrontal regions that are involved in the retrieval and selection of semantic information. The results suggest that area PE serves as a critical interface between posterior cortical regions in the left hemisphere involved in language processing and the central motor and sensory regions that are directly involved in the control of movement.

Distinct critical cerebellar subregions for components of verbal working memory

A role for the cerebellum in cognition has been proposed based on studies suggesting a profile of cognitive deficits due to cerebellar stroke. Such studies are limited in the determination of the detailed organisation of cerebellar subregions that are critical for different aspects of cognition. In this study we examined the correlation between cognitive performance and cerebellar integrity in a specific degeneration of the cerebellar cortex: Spinocerebellar Ataxia type 6 (SCA6). The results demonstrate a critical relationship between verbal working memory and grey matter density in superior (bilateral lobules VI and crus I of lobule VII) and inferior (bilateral lobules VIIIa and VIIIb, and right lobule IX) parts of the cerebellum. We demonstrate that distinct cerebellar regions subserve different components of the prevalent psychological model for verbal working memory based on a phonological loop. The work confirms the involvement of the cerebellum in verbal working memory and defines specific subsystems for this within the cerebellum.

Different components of working memory have different relationships with different mathematical skills

A comprehensive working memory battery and tests of mathematical skills were administered to 90 children—41 in Year 1 (5–6 years of age) and 49 in Year 3 (7–8 years of age). Working memory could explain statistically significant variance in number writing, magnitude judgment, and single-digit arithmetic, but the different components of working memory had different relationships with the different skills. Visual–spatial sketchpad (VSSP) functioning predicted unique variance in magnitude judgments and number writing. Central executive functioning explained unique variance in the addition accuracy of Year 1 children. The unique variance explained in Year 3 multiplication explained by phonological loop functioning just missed conventional levels of significance ( p = .06). The results are consistent with the VSSP having a role in the development of number writing and magnitude judgments but a lesser role in early arithmetic.

Letter Naming and Letter Writing Reversals in Children With Dyslexia: Momentary Inefficiency in the Phonological and Orthographic Loops of Working Memory

Given mounting evidence for working memory impairments in dyslexia, letter reversals during rapid automatic letter naming (phonological loop) or rapid automatic letter writing (orthographic loop) may reflect momentary inefficiency of working memory. Few of the children, with or without dyslexia, in a multi-generational family genetics study, produced reversals, but those with dyslexia produced more than those without dyslexia. Working-memory component predictors (word storing and processing units, phonological and orthographic loops, and executive functions) in regressions differentiated children with dyslexia (average age 11) who did and did not make reversals, predicted the number of reversals on specific letter naming or letter writing tasks, and explained unique variance in reading and writing outcomes. Although reversals are not a hallmark defining feature of dyslexia, children who produce reversals may benefit from instruction designed to develop specific working memory components and their efficient coordination in time.

Working Memory Contributions to Reading Comprehension Components in Middle Childhood Children

This study examined working memory contributions to reading comprehension subskills in Greek children (mean age 9 years, 1 month). The phonological loop of the Baddeley and Hitch working memory model was assessed with 3 recall tasks (words, nonwords, and digits) and a word list matching task. The central executive (CE) was assessed with 3 tasks (listening, counting, and backward digit recall). Participants were also given a receptive vocabulary task, a reading fluency task, and written stories accompanied by comprehension questions. Canonical correlation analyses showed that the comprehension variables were related to the CE rather than the phonological loop measures. CE functions were more strongly associated with elaborative inference generation (involving significant offline processing) and comprehension control (involving metacognitive monitoring). Smaller yet significant associations were observed between the CE and the necessary inference and literal comprehension measures, whereas a moderate relationship was found in the case of the simile comprehension variable. Among the CE variables, listening recall demonstrated the highest loading on the canonical function, followed by moderate yet significant counting and backward digit recall loadings. Vocabulary was found to fully mediate several associations between working memory and comprehension measures; however, the relationship between listening recall and elaborative inferences was partly mediated. Reading fluency and, on several occasions, Greek vocabulary knowledge did not mediate the relationships between CE measures and comprehension skills assessed. This study demonstrates the usefulness of CE measures for identifying young children's possible difficulties in carrying out specific reading comprehension processes.

Acute glucocorticoid effects on the multicomponent model of working memory

In comparison with basal physiological levels, acute, high levels of cortisol affect learning and memory. Despite reports of cortisol-induced episodic memory effects, no study has used a comprehensive battery of tests to evaluate glucocorticoid effects on the multicomponent model of working memory. Here, we report the results of a double-blind, placebo-controlled, between-subjects study. Twenty healthy young men were randomly assigned to either acute cortisol (30 mg hydrocortisone) or placebo administration. Participants were subjected to an extensive cognitive test battery that evaluated all systems of the multicomponent model of working memory, including various executive domains (shifting, updating, inhibition, planning and access to long-term memory). Compared with placebo, hydrocortisone administration increased cortisol blood levels and impaired working memory in storage of multimodal information in the episodic buffer and maintenance/reverberation of information in the phonological loop. Hydrocortisone also decreased performance in planning and inhibition tasks, the latter having been explained by changes in storage of information in working memory. Thus, hydrocortisone acutely impairs various components of working memory, including executive functioning. This effect must be considered when administering similar drugs, which are widely used for the treatment of many clinical disorders.