Linking working memory and long-term memory: A computational model of the learning of new words

The nonword repetition (NWR) test has been shown to be a good predictor of children’s vocabulary size. NWR performance has been explained using phonological working memory, which is seen as a critical component in the learning of new words. However, no detailed specification of the link between phonological working memory and long-term memory (LTM) has been proposed. In this paper, we present a computational model of children’s vocabulary acquisition (EPAM-VOC) that specifies how phonological working memory and LTM interact. The model learns phoneme sequences, which are stored in LTM and mediate how much information can be held in working memory. The model’s behaviour is compared with that of children in a new study of NWR, conducted in order to ensure the same nonword stimuli and methodology across ages. EPAM-VOC shows a pattern of results similar to that of children: performance is better for shorter nonwords and for wordlike nonwords, and performance improves with age. EPAM-VOC also simulates the superior performance for single consonant nonwords over clustered consonant nonwords found in previous NWR studies. EPAM-VOC provides a simple and elegant computational account of some of the key processes involved in the learning of new words: it specifies how phonological working memory and LTM interact; makes testable predictions; and suggests that developmental changes in NWR performance may reflect differences in the amount of information that has been encoded in LTM rather than developmental changes in working memory capacity. Keywords: EPAM, working memory, long-term memory, nonword repetition, vocabulary acquisition, developmental change

HIV infection significantly reduces lipoprotein lipase which remains low after 6 months of antiretroviral therapy

Purpose of the study Fractional clearance rate of apolipoprotein B100-containing lipoproteins is reduced in HIV infection before and after antiretroviral (ARV) treatment [1]. We compared lipoprotein lipase (LPL) activity and gene expression in HIV-positive subjects before and 6 months after ARV with HIV-negative controls. Methods Fasting blood post heparin total and hepatic lipase activity,adiponectin, leptin, insulin, glucose, and lipid measurementswere made in 32 HIV-infected and 15 HIVnegative controls. LPL was estimated by subtractinghepatic lipase from total lipase. Adiponectin, LPL andhormone sensitive lipase (HSL) gene expression weremeasured from iliac crest subcutaneous fat biopsies.Patients were tested before, and 6 months after randomisation to AZT/3TC (n = 15) or TDF/FTC (n = 17) with EFV.Between-group comparison was by Mann-Whitney andpaired samples by the Wilcoxon signed rank tests. Summary of results There were no differences in gender, ethnicity, baseline BMI, regional fat distribution (whole body DEXA) and visceral (VAT) and subcutaneous fat (SAT) measured by abdominal CT scans between controls and patients. Trunk fat/BMI ratio, VAT and VAT:SAT ratio significantly increased after 6-month ARV therapy (p = 0.01). There were no differences between groups in serum NEFA,HOMA and leptin levels. Selected other results are shown in Table 1. Conclusion Post heparin lipoprotein lipase activity is reduced in HIV and does not return to control levels after 6 months of ARV therapy. AZT-containing regimens are associated with a greater increase in LPL, LPL gene expression and plasma adiponectin than TDF

The preschool repetition test: An evaluation of performance in typically developing and clinically referred children

Purpose: To determine the psychometric properties of the Preschool Repetition Test (Roy & Chiat, 2004); to establish the range of performance in typically developing children and variables affecting this; and to compare the performance of clinically referred children. Method: The PSRep Test comprises 18 words and 18 phonologically matched nonwords systematically varied for length and prosodic structure. This test was administered to a ‘typical’ sample of children aged 2;0–4;0 (n=315) and a ‘clinic’ sample of children aged 2;6-4;0 (n=168), together with language assessments. Results: Performance in the typical sample was independent of gender and SES, but was affected by age, item length, and prosodic structure, and was moderately correlated with receptive vocabulary. Performance in the clinic sample was significantly poorer, but revealed similar effects of length and prosody, and similar relations to language measures overall, with some notable exceptions. Test-retest and interrater reliability were high. Conclusions: The PSRep Test is a viable and informative test. It differentiates within and between ‘typical’ and ‘clinic’ samples of children, and reveals some unusual profiles within the clinic sample. These findings lay the foundations for a follow-up study of the clinic sample to investigate the predictive value of the test

A prosodically controlled word and nonword repetition task for 2- to 4- year-olds: Evidence from typically developing children

An association has been found between nonword repetition and language skills in school-aged children with both typical and atypical language development (Dollaghan & Campbell, 1998; Ellis Weismer et al., 2000; Gathercole & Baddeley, 1990; Montgomery, 2002). This raises the possibility that younger children’s repetition performance may be predictive of later language deficits. In order to investigate this possibility, it is important to establish that elicited repetition with very young children is both feasible and informative. To this end, a repetition task was designed and carried out with 66 children aged 2-4. The task consisted of 18 words and 18 matched nonwords that were systematically manipulated for length and prosodic structure. In addition, an assessment of receptive vocabulary was administered. The repetition task elicited high levels of response. Total scores as well as word and nonword scores were sensitive to age. Lexical status and item length affected performance regardless of age: words were repeated more accurately than nonwords, and one-syllable items were repeated more accurately than two-syllable items, which were in turn repeated more accurately than three-syllable items. The effect of prosodic structure was also significant. Whole syllable errors were almost exclusive to unstressed syllables, with those preceding stress being most vulnerable. Performance on the repetition task was significantly correlated with performance on the receptive vocabulary test. Since this repetition task was effective in eliciting responses from most of the 2 to 4-year-old participants, tapped developmental change in their repetition skills, and revealed patterns in their performance, it has the potential to identify deficits in very early repetition skills that may be indicative of wider language difficulties

Observations on morphologic changes in the aging and degenerating human disc: Secondary collagen alterations

BACKGROUND: In the annulus, collagen fibers that make up the lamellae have a wavy, planar crimped pattern. This crimping plays a role in disc biomechanical function by allowing collagen fibers to stretch during compression. The relationship between morphologic changes in the aging/degenerating disc and collagen crimping have not been explored. METHODS: Ultrastructural studies were performed on annulus tissue from 29 control (normal) donors (aged newborn to 79 years) and surgical specimens from 49 patients (aged 16 to 77 years). Light microscopy and specialized image analysis to visualize crimping was performed on additional control and surgical specimens. Human intervertebral disc tissue from the annulus was obtained in a prospective morphologic study of the annulus. Studies were approved by the authors' Human Subjects Institutional Review Board. RESULTS: Three types of morphologic changes were found to alter the crimping morphology of collagen: 1) encircling layers of unusual matrix disrupted the lamellar collagen architecture; 2) collagen fibers were reduced in amount, and 3) collagen was absent in regions with focal matrix loss. CONCLUSIONS: Although proteoglycan loss is well recognized as playing a role in the decreased shock absorber function of the aging/degenerating disc, collagen changes have received little attention. This study suggests that important stretch responses of collagen made possible by collagen crimping may be markedly altered by morphologic changes during aging/degeneration and may contribute to the early tissue changes involved in annular tears

The impact of sound field systems on learning and attention in elementary school classrooms

Purpose: An evaluation of the installation and use of sound field systems (SFS) was carried out to investigate their impact on teaching and learning in elementary school classrooms. Methods: The evaluation included acoustic surveys of classrooms, questionnaire surveys of students and teachers and experimental testing of students with and without the use of SFS. Students ’ perceptions of classroom environments and objective data evaluating change in performance on cognitive and academic assessments with amplification over a six month period are reported. Results: Teachers were positive about the use of SFS in improving children’s listening and attention to verbal instructions. Over time students in amplified classrooms did not differ from those in nonamplified classrooms in their reports of listening conditions, nor did their performance differ in measures of numeracy, reading or spelling. Use of SFS in the classrooms resulted in significantly larger gains in performance in the number of correct items on the nonverbal measure of speed of processing and the measure of listening comprehension. Analysis controlling for classroom acoustics indicated that students ’ listening comprehension score

The acquisition of Sign Language: The impact of phonetic complexity on phonology

Research into the effect of phonetic complexity on phonological acquisition has a long history in spoken languages. This paper considers the effect of phonetics on phonological development in a signed language. We report on an experiment in which nonword-repetition methodology was adapted so as to examine in a systematic way how phonetic complexity in two phonological parameters of signed languages — handshape and movement — affects the perception and articulation of signs. Ninety-one Deaf children aged 3–11 acquiring British Sign Language (BSL) and 46 hearing nonsigners aged 6–11 repeated a set of 40 nonsense signs. For Deaf children, repetition accuracy improved with age, correlated with wider BSL abilities, and was lowest for signs that were phonetically complex. Repetition accuracy was correlated with fine motor skills for the youngest children. Despite their lower repetition accuracy, the hearing group were similarly affected by phonetic complexity, suggesting that common visual and motoric factors are at play when processing linguistic information in the visuo-gestural modality

Remember some or remember all? Ageing and strategy effects in visual working memory

Recent research (Bengson & Luck, 2015) has indicated that visual working memory capacity for unidimensional items might be boosted by focusing on all presented items, as opposed to a subset of them. However, it is not clear whether the same outcomes would be observed if more complex items were used which require feature binding, a potentially more demanding task. The current experiments therefore examined the effects of encoding strategy using multidimensional items in tasks that required feature binding. Effects were explored across a range of different age groups (Experiment 1) and task conditions (Experiment 2). In both experiments, participants performed significantly better when focusing on a subset of items, regardless of age or methodological variations, suggesting this is the optimal strategy to employ when several multidimensional items are presented and binding is required. Implications for task interpretation and visual working memory function are discussed