Academic literature on the topic 'Working Memory Index'

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most prominent neurobehavioral disorders of childhood that is heavily researched and often revised. Deficits in attention/concentration, impulsivity, inhibition, information processing speed, working memory and executive functioning manifest differently according to subtype diagnosis for both children and adults. As a result, previous attempts to construct a unifying theory of ADHD with neural correlates and quantifiable performance discrepancies have resulted in a proliferation of literature reviews citing both significant and insignificant research findings. The purpose of the current study was to construct a homogenous sample of children diagnosed with ADHD and examine purported subtype differences in working memory and information processing speed using the Wechsler Intelligence Scales for Children - Forth Edition (WISC-IV). Sixty participants were selected from archival data from two clinical sites and separated into three groups according to the current DSM-IV-TR ADHD subtype criteria: ADHD Predominately Inattentive type (ADHD-IN), ADHD Predominately Hyperactive/Impulsive type (ADHD-HY), and ADHD Combined type (ADHD-C). Significant differences within groups were revealed on the Coding subtest and Processing Speed Index (PSI) relative to performance on the Perceptual Reasoning Index (PRI). No significant between groups or interaction effects were revealed. While the goal of the current study was aimed at discovering evidence of greater deficits in processing speed by the ADHD-IN group compared to the other two groups, processing speed was reduced for the entire sample providing more evidence of a possible neurological deficit/basis inherent to ADHD. The results of the current study provided minimal evidence of differences on WISC-IV measures of working memory within the current sample. The current study was successful in correcting previous methodological flaws inherent in the relevant literature by constructing a truly homogenous sample of ADHD and provided strong evidence for the necessity of an accurate diagnosis of ADHD subtypes.

Deficits in working memory are typical symptoms in schizophrenia. The gene for the Dopamine Receptor 1 (DRD1) is one of the candidate genes for schizophrenia, and it is critical for memory function. Magnetic Resonance Imaging (fMRI) was used to detect neurocircuitries engaged during a behavioral task of subjects with chronic schizophrenia and healthy people. Multivariate analysis in particular Partial Least Squares, was adopted to quantitatively capture diagnosis-specific patterns. The brain-behavior analyses identified diagnosis-specific circuitries that included many cortical areas. Furthermore, we compared two groups of schizophrenics with different DRD1 genotype. The imaging-genetics analysis showed that covariance patterns of different areas (including the dorsolateral prefrontal cortex and the inferior parietal lobule) were inversely related between the two genotypes. Therefore, it appears that the speed in subjects' response may be indicative of diagnostic-specific networks, and that DRD1 genotype may suggest differential use of neural networks.

The study examines language, memory and reading skills in children from two private schools in Victoria, British Columbia. Phonological processing and word-level decoding were significantly correlated, suggesting that familiarity with letters and their associated sounds are important for word-level reading. Phonological processing and decoding skill performance were significantly correlated with STM span and not WM span, suggesting that word-level decoding is not attentionally demanding for this sample of children. Decoding speed was inversely related to STM span; faster reading times and larger STM spans were highly predictive of one another. The children’s WM and STM task performance were relatively similar and may be reflective of efficient strategy use, such as word recognition, which reduces attention for processing in WM.

The “All-or-None Hypothesis (ANH)” (Diamond, 2005; 2006) was examined, positing that executive systems process information and respond to the environment using global heuristics, versus a more piecemeal approach. 104 adults were tested on two novel paradigms designed to uniquely test the ANH. Working Memory (WM) and Inhibitory Control (IC) demands were manipulated, to test the impact of these task demands. Performance measured by reaction times and accuracy on both paradigms provided some support for the ANH. However, this effect was greatest when participants required ‘executive-type’ inhibition, versus ‘motor-type’ inhibition to suppress a response. Further, increasing the WM load increased the ANH trend, while varying the IC requirements had little effect. To our knowledge this is the first direct test of Diamond’s ANH, and extended its specificity in terms of task demands.

Le processus de vieillissement humain est un processus complexe qui varie grandement d’une personne à l’autre. Malgré l’ampleur des recherches faites sur le sujet, il reste encore beaucoup à explorer et à comprendre. Cette thèse propose trois expériences qui nous permettent d’améliorer notre compréhension des changements qui s’opèrent dans la mémoire de travail visuelle et l’attention visuospatiale avec la prise en âge. La première expérience propose d’examiner les changements dans les capacités de mémoire de travail visuelle entre des jeunes adultes, des adultes âgés sains et des personnes atteintes de trouble cognitif léger (TCL). De plus, grâce à un suivi fait avec les personnes ayant un TCL, nous avons pu examiner si des différences existaient au niveau comportemental entre les âgés qui ont déclinés vers un type de démence et ceux dont l’état est resté stable. Plusieurs techniques peuvent être utilisées pour étudier les effets du vieillissement sur le cerveau. Les tests neuropsychologiques et les tâches comportementales présentées dans la première expérience en sont un exemple. La neuroimagerie peut aussi s’avérer particulièrement utile. En effet, certaines mesures électrophysiologiques, aussi appelées potentiels reliés aux évènements (PRE), sont associées à des fonctions cognitives précises. Ces composantes nous permettent de suivre ces processus et d’observer les modulations causées par les caractéristiques des stimuli ou l’âge par exemple. C’est le cas de la N2pc (négativité 2 postérieure controlatérale) et de la SPCN (sustained posterior contralateral negativity), des composantes électrophysiologiques liées respectivement à l’attention visuospatiale et la mémoire de travail visuelle. On connait bien ces deux composantes ainsi que les facteurs qui les modulent, or elles sont peu utilisées pour les changements qui occurrent dans l’attention et la mémoire de travail visuelle dans le cadre du processus de vieillissement. Les deuxième et troisième expériences proposent d’utiliser une tâche de recherche visuelle (nombre d’items de couleur et identification d’une relation spatiale entre deux items de couleur) afin d’explorer les changements observables sur ces composantes électrophysiologiques. La deuxième expérience examine l’efficacité d’un paradigme à présentations multiples (‘multiple frame’) afin de mesurer la N2pc et la SPCN chez de jeunes adultes. La troisième expérience a pour but d’examiner les effets du vieillissement normal sur l’amplitude et la latence de la N2pc et la SPCN en utilisant le même type de tâche de recherche visuelle.<br>Human ageing is a complex process that varies a lot from one person to the other. Despite the scope of research of that subject, there is still a lot to explore. This thesis proposes three experiments that will help increase our understanding of the many changes in visual working memory and visuospatial attention seen in ageing. The first experiment assesses the changes in visual working memory capacities between young adults, healthy older adults, and persons with MCI. Furthermore, we were able to do a follow-up with the persons with MCI and determine which ones remained in a stable cognitive state and the ones that decline toward mild dementia, providing us with the opportunity to test for potential behavioral differences allowing us to distinguish between them. Many techniques, such as neuropsychological tests and behavioral tasks, can be used to study the effects of ageing on the brain. Neuroimaging techniques can be particularly useful. In fact, many electrophysiological measures, called event-related potentials (ERPs), are linked to specific cognitive functions which allow us to follow those processes and observe the modulations caused by stimuli characteristics or ageing for example. This is the case of the N2pc (negativity 2 posterior contralateral) and the SPCN (sustained posterior contralateral negativity), two ERPs linked to visuospatial attention and visual working memory. While they are both well-known in the literature, not many studies are using them as a way to examine the changes appearing in the visuospatial attention and the visual working memory during the normal ageing process. The second and third experiment use a visual search task (including 2 conditions: counting the number of items presented and identify a specific spatial relation between 2 coloured items) to explore the changes seen on those ERPs. The second experiment wants to assess the efficiency of a multiple frame paradigm to measure the N2pc and the SPCN with young adults. The third experiment wants to examine the effects of normal ageing on the amplitude and the latency of the two components using the same type of visual search task.

Objective: The goal of this study was to investigate relations between aspects of cognitive control and emotion in typically developing children, 7 to 9 years of age. This was investigated by examining performance on n-back working memory tasks that varied according to the level of cognitive control and emotion (e.g., faces, reward value) processing required. Relations between n-back performance and parental questionnaires of behavior were also examined. Participants & Methods: Participants included 77 typically developing children, 7 to 9 years of age. Each participant completed two novel n-back tasks. The first task involved working memory (0-back, 1-back, and 2-back levels) for emotional faces (neutral, happy, sad). The second task involved working memory (0-back, 1-back, and 2-back levels) for number stimuli with differing levels of reward (two tokens, six tokens). Matrix Reasoning was also completed as a screening measure of cognitive function. Parents completed a Child History questionnaire, the BRIEF, Conners 3 AI-Parent, and the Emotion Questionnaire. iv Results: No significant main effect was found for emotive content of stimuli or reward value. A significant effect of n-back level was found, both in terms of per hit RT and accuracy rates for both Emotive and Reward n-back. Significant relations were found between age and Sad conditions on 1-back and 2-back of the Emotive n-back, as well as 2-back conditions in the Reward n-back. No relations were found between BRIEF scales and performance on either n-back task. Significant correlations were found between Emotionality and accuracy measures of the Reward n-back task. Conclusions: This study made several important contributions to understanding emotion and cognitive control interplay. These contributions include introducing novel tasks for assessing this interplay, and providing insight on developmental relations and interaction between emotion and working memory and individual differences in emotionality in day to day life. Results are discussed with respect to theories of emotional and cognitive control interplay, temperament and individual differences, and the development of cognitive control. Directions for future research and implications are discussed.