Cerebellar contributions to verbal working memory: beyond cognitive theory

The role of verbal and visuospatial working memory in rule-based and information-integration category learning was examined. Previously, Maddox, Ashby, Ing, and Pickering found that a sequentially presented verbal working memory task did not affect information-integration learning, but disrupted rule-based learning when the rule was on the spatial frequency of a Gabor stimulus. This pattern was replicated in Experiment 1, in which the same category structures were used, but in which the verbal working memory task was replaced with a visuospatial analog. Experiment 2A examined rule-based learning on an oblique orientation and also found both verbal and visuospatial working memory tasks disrupting learning. Experiment 2B examined rule-based learning on a cardinal orientation and found a minimal effect of the verbal working memory task, but a large effect of the visuospatial working memory task. The conceptual significance of cardinal orientations and the role of visuospatial and verbal working memory in category learning are discussed.

This article reviews current models of verbal working memory and considers the role of language comprehension and long-term memory in the ability to maintain and order verbal information for short periods of time. While all models of verbal working memory posit some interaction with long-term memory, few have considered the character of these long-term representations or how they might affect performance on verbal working memory tasks. Similarly, few models have considered how comprehension processes and production processes might affect performance in verbal working memory tasks. Modern theories of comprehension emphasize that people learn a vast web of correlated information about the language and the world and must activate that information from long-term memory to cope with the demands of language input. To date, there has been little consideration in theories of verbal working memory for how this rich input from comprehension would affect the nature of temporary memory. There has also been relatively little attention to the degree to which language production processes naturally manage serial order of verbal information. The authors argue for an emergent model of verbal working memory supported by a rich, distributed long-term memory for language. On this view, comprehension processes provide encoding in verbal working memory tasks, and production processes maintenance, serial ordering, and recall. Moreover, the computational capacity to maintain and order information varies with language experience. Implications for theories of working memory, comprehension, and production are considered.

Characterization of a normal control group: Are they healthy?

Contributions of language and memory demands to verbal memory performance in language-learning disabilities

Verbal working memory is poorer for children with hearing loss than for peers with normal hearing (NH), even with cochlear implantation and early intervention. Poor verbal working memory can affect academic performance, especially in higher grades, making this deficit a significant problem. This study examined the stability of verbal working memory across middle childhood, tested working memory in adolescents with NH or cochlear implants (CIs), explored whether signal enhancement can improve verbal working memory, and tested two hypotheses proposed to explain the poor verbal working memory of children with hearing loss: (a) Diminished auditory experience directly affects executive functions, including working memory; (b) degraded auditory inputs inhibit children's abilities to recover the phonological structure needed for encoding verbal material into storage. Fourteen-year-olds served as subjects: 55 with NH; 52 with CIs. Immediate serial recall tasks were used to assess working memory. Stimuli consisted of nonverbal, spatial stimuli and four kinds of verbal, acoustic stimuli: nonrhyming and rhyming words, and nonrhyming words with two kinds of signal enhancement: audiovisual and indexical. Analyses examined (a) stability of verbal working memory across middle childhood, (b) differences in verbal and nonverbal working memory, (c) effects of signal enhancement on recall, (d) phonological processing abilities, and (e) source of the diminished verbal working memory in adolescents with cochlear implants. Verbal working memory remained stable across middle childhood. Adolescents across groups performed similarly for nonverbal stimuli, but those with CIs displayed poorer recall accuracy for verbal stimuli; signal enhancement did not improve recall. Poor phonological sensitivity largely accounted for the group effect. The central executive for working memory is not affected by hearing loss or cochlear implantation. Instead, the phonological deficit faced by adolescents with CIs denigrates the representation in storage and augmenting the signal does not help.

Rational number understanding is a critical building block for success in more advanced mathematics; however, how rational number magnitudes are conceptualized is not fully understood. In the current study, we used a dual-task working memory (WM) interference paradigm to investigate the dominant type of strategy (i.e., requiring verbal WM resources vs. requiring primarily visuospatial WM resources) used by adults when processing rational number magnitudes presented in both decimal and fraction notation. Analyses revealed no significant differences in involvement of verbal and visuospatial WM, regardless of notation (fractions vs. decimals), indicating that adults rely upon a mix of strategies and WM resources when processing rational number magnitudes. However, this pattern interacted with algebra ability such that those performing better on the algebra assessment relied upon both verbal and visuospatial WM when engaging in rational number comparisons, whereas rational number performance by adults with low algebra fluency was affected only by a simultaneous verbal WM task. Together, results support previous work implicating the involvement of WM resources in rational number processing and is the first study to indicate that the involvement of both verbal and visuospatial WM, as opposed to relying primarily on verbal WM, when processing rational number magnitudes may be indicative of higher mathematical proficiency in the domain of algebra. (PsycINFO Database Record (c) 2017 APA, all rights reserved)

Many aspects of human performance require producing sequences of items in serial order. The current study takes a multiple-case approach to investigate whether the system responsible for serial order is shared across cognitive domains, focusing on working memory (WM) and word production. Serial order performance in three individuals with post-stroke language and verbal WM disorders (hereafter persons with aphasia, PWAs) were assessed using recognition and recall tasks for verbal and visuospatial WM, as well as error analyses in spoken and written production tasks to assess whether there was a tendency to produce the correct phonemes/letters in the wrong order. One PWA exhibited domain-specific serial order deficits in verbal and visuospatial WM. The PWA with verbal serial order WM deficit made more serial order errors than expected by chance in both repetition and writing-to-dictation tasks, whereas the other two PWAs showed no serial order deficits in verbal WM and production tasks. These findings suggest separable serial order systems for verbal and visuospatial WM and a shared system for serial order processing in verbal WM and word production. Implications for the domain-generality of WM, its connection to language production, and serial order processing across cognitive functionssc are discussed.

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.

Background: Studies have indicated that failure to eat breakfast did not affect children's performance in general cognitive tests; however, skipping breakfast might have effects on the specific aspects of cognition such as memory. Hypothetically, language as a higher cognitive function may be influenced by breakfast consumption routines. Objectives: This study aimed to compare students' verbal fluency and working memory according to their breakfast routines. Methods: We selected 60 seven-year-old children from three primary schools in the central regions of Tehran in 2017. Their parents were invited to a structured interview to fill out questionnaires consisting of information related to the child, parent, and breakfast routines. Based on the family's breakfast habits, two groups were identified: Group 1 with a full, regular breakfast routine and Group 2 with no breakfast or incomplete breakfast routine. An experienced speech therapist administered the verbal fluency task (phonemic and semantic fluency) and verbal working memory task (forward and backward digit numbers) for each student. Results: The mean scores of students with a full breakfast routine on verbal fluency tasks were at least three units more than those of students without breakfast. These differences were all significant (P = 0.001). In working memory tasks, students with a full breakfast routine had seven digits and one digit in their responses more than students without breakfast in forward and backward digit tasks, in sequence. These differences were significant (P = 0.001). Conclusions: The findings of the present study provide information on the positive effects of a regular breakfast routine on the specific cognitive functions related to language processing.

The cerebellum is often active in imaging studies of verbal working memory, consistent with a putative role in articulatory rehearsal. While patients with cerebellar damage occasionally exhibit a mild impairment on standard neuropsychological tests of working memory, these tests are not diagnostic for exploring these processes in detail. The current study was designed to determine whether damage to the cerebellum is associated with impairments on a range of verbal working memory tasks, and if so, under what circumstances. Moreover, we assessed the hypothesis that these impairments are related to impaired rehearsal mechanisms. Patients with damage to the cerebellum (n = 15) exhibited a selective deficit in verbal working memory: spatial forward and backward spans were normal, but forward and backward verbal spans were lower than controls. While the differences were significant, digit spans were relatively preserved, especially in comparison to the dramatic reductions typically observed in classic 'short-term memory' patients with perisylvian brain damage. The patients tended to be more impaired on a verbal version compared to a spatial version of a working memory task with a long delay and this impairment was correlated with overall symptom and dysarthria severity. These results are consistent with a contribution of the cerebellum to rehearsal and suggest that inclusion of a delay before recall is especially detrimental in individuals with cerebellar damage. However, when we examined markers of rehearsal (i.e. word-length and articulatory suppression effects) in an immediate serial recall task, we found that qualitative aspects of the patients' rehearsal strategies were unaffected. We propose that the cerebellum may contribute to verbal working memory during the initial phonological encoding and/or by strengthening memory traces rather than by fundamentally subserving covert articulatory rehearsal.

Working memory deficits are present in patients with mild traumatic brain injury (MTBI). Functional connectivity of different brain regions is required for adequate working memory. Brain injury is associated with disrupted connectivity due to microscopic axonal damage. In this investigation, we sought to investigate functional brain connectivity during working memory in MTBI patients. A sample of 30 MTBI patients and 30 age-, education-, and gender-matched normal controls were studied. Working memory was assessed with the Sternberg's verbal and visuo-spatial working memory tasks. Electro-encephalography (EEG) was recorded from 128 channels while subjects performed working memory tasks and during eyes closed resting condition. EEG coherence was computed in theta; lower and upper alpha; and lower and upper beta frequency bands during the encoding, retention, and retrieval stages of working memory as well as during eyes-closed rest. We found that the MTBI patients had impaired verbal and visuo-spatial working memory. The different stages of working memory were associated with poor intrahemispheric coherence in long-range (fronto-parietal) and mid-range (fronto-temporal and temporo-parietal) regions as well as poor interhemispheric coherence in the frontal and temporal regions in the MTBI patients. The deficit in coherence was present in theta, alpha, and beta frequency bands. However, the MTBI and the control group had comparable coherence values in intra- and inter-hemispheric regions during eyes closed rest. We suggest that the inter- and intra-hemispheric functional connectivity is impaired in MTBI during working memory performance.

In both animals and humans, nicotine produces behavioral effects that vary across individuals. Studies examining the role of genetic variability in modulating individual response to nicotine in humans have increased, with recent work showing that genetic variation at the dopamine D2 receptor (DRD2) predicts response to pharmacotherapy for tobacco dependence. To determine whether a polymorphism of the DRD2 gene, C957T, that alters DRD2 binding availability in humans modifies the effects of nicotine on verbal working memory performance and on processing efficiency of brain regions that support verbal working memory. Working memory and brain function were assessed in 36 adult subjects (15,957T allele carriers and 21,957C homozygotes), each of whom was studied twice, once after placement of a placebo patch and once after placement of a nicotine patch. Brain function was assessed using functional magnetic resonance imaging while the subjects performed a verbal working memory task. During performance of a task with high verbal working memory load, nicotine administration worsened performance accuracy and reduced the processing efficiency of brain regions that support phonological rehearsal during verbal working memory in carriers of the 957T allele. These findings are consistent with the notion that genetic variation in DRD2 contributes to individual variation in a range of behavioral and brain responses to nicotine in humans.

This study sheds light on the effect of bilingualism on working memory performance. It aims to investigate whether bilingual speakers have an advantage over monolingual speakers in performing visual-spatial working memory tasks. The present study attempts to be a contribution to the discussion of how working memory performance is affected by bilingualism. It tries to find out whether Arabic-English bilingual speakers have advantages over Arabic monolingual speakers in performing visual-spatial working memory tasks. Two experiments were conducted to test the working memory performance of bilinguals and monolinguals by using verbal and non-verbal tasks. The two measures were completed online; the non-verbal measure involved a picture memorization task, whereas the verbal measure involved word retrieval. Eighty female college students voluntarily participated in the study. Half were Arabic-English bilinguals, and the other half were Arabic monolinguals. Both groups were divided into two subgroups; half performed a non-verbal working memory task, and the other half participated in a verbal working memory task. The results showed no advantages for bilinguals in the picture memorization task. However, a bilingual advantage was found in the verbal working memory task in which bilingual speakers performed better in word retrieval compared to monolingual speakers. The findings indicate a positive effect of bilingualism on working memory performance, particularly in the visual-spatial component.

Atypical frontal lobe activity during verbal working memory in youth with a family history of alcoholism

The neurodevelopmental differences of increasing verbal working memory demand in children and adults