Dot Enumeration Perceptual Organization Task (DEPOT): evidence for a short-term visual memory deficit in schizophrenia

The Dot Enumeration Perceptual Organization Task (DEPOT) evaluates the validity of 2 specific competing cognitive models of early input dysfunction in schizophrenic individuals: a primary Stage 1, sensory store, perceptual organization deficit vs. a Stage 2, short-term visual memory (STVM) deficit. DEPOT was also designed to assess the hypothesis that schizophrenic individuals tend to perform poorly on all cognitive tasks. In DEPOT both number and form judgments are made about the same dot patterns. A response delay manipulation assesses the persistence and operation of STVM. The study included 41 psychotic inpatients (8 with acute and 16 with chronic schizophrenia and 7 with bipolar and 10 with nonbipolar affective disorder) and 38 controls (22 college students and 16 hospital personnel). Although the pattern of results was consistent with neither the Stage 1 deficit nor the general deficit hypotheses, a Stage 2, STVM deficit hypothesis could account parsimoniously for the data.     

Patterns of cognitive impairment in relapsing–remitting multiple sclerosis and their relationship to neuropathology on magnetic resonance images.

Several reviews (J. M. Peyser & C. M. Poser, 1986; S. M. Rao, 1986) have suggested that multiple sclerosis (MS) results in cognitive impairment in learning and memory, abstract reasoning, information-processing efficiency, and often visual–spatial ability. MS patients may undergo idiosyncratic cognitive changes dependent on the site of white matter lesions. In the present study, researchers used cluster analysis on the neuropsychological data from a group of mildly disabled relapsing–remitting MS patients (n&≠&?77) and a well-matched control group (n&≠&?9). In those MS patients identified with unequivocal cognitive impairment, the majority clustered into groups with a specific deficit in 1 or 2 areas of cognitive functioning, with normal performance in others. On magnetic resonance imaging, an association was obtained between 2 lesion sites and 2 cognitive tests. Impairment in visual–spatial ability, as assessed by the Benton Visual Retention Test, was associated with lesions in the genu of the corpus callosum (CC) and with more lesions throughout the CC. Impaired performance on Paired Associates, a test of learning and memory, was associated with a lesion in the deep white matter of the left parietal lobe… (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging increases inattentional blindness to the gorilla in our midst.

When engaged in an attention-demanding task, people are surprisingly vulnerable to inattentional blindness—the failure to notice an unexpected event. Two theories of cognitive aging, attentional capacity models and inhibitory deficit models, make opposite predictions about age differences in susceptibility to inattentional blindness. We tested these predictions using an inattentional blindness paradigm developed by Simons and Chabris (1999) and found that older adults were more likely to experience inattentional blindness than young adults. These results are compatible with attentional capacity models of cognitive aging but not with current inhibitory deficit models. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Multinomial modeling and the measurement of cognitive processes.

This article presents a detailed discussion and application of a methodology, called multinomial modeling, that can be used to measure and study cognitive processes. Multinomial modeling is a statistically based technique that involves estimating hypothetical parameters that represent the probabilities of unobservable cognitive events. Models in this class provide a statistical methodology that is compatible with computational theories of cognition. Multinomial models are relatively uncomplicated, do not require advanced mathematical techniques, and have certain advantages over other, more traditional methods for studying cognitive processes. The statistical methodology behind multinomial modeling is briefly discussed, including procedures for data collection, model development, parameter estimation, and hypothesis testing. Three substantive examples of multinomial modeling are presented. Each example, taken from a different area within the field of human memory, involves the development of a multinomial model and its application to a specific experiment. It is shown how multinomial models facilitate the interpretation of the experiments. The conclusion discusses the general advantages of multinomial models and their potential application as research tools for the study of cognitive processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Journey to the center of the category: The dissociation in amnesia between categorization and recognition.

The authors' theoretical analysis of the dissociation in amnesia between categorization and recognition suggests these conclusions: (a) Comparing to-be-categorized items to a category center or prototype produces strong prototype advantages and steep typicality gradients, whereas comparing to-be, categorized items to the training exemplars that surround the prototype produces weak prototype advantages and flat typicality gradients; (b) participants often show the former pattern, suggesting their use of prototypes; (c) exemplar models account poorly for these categorization data, but prototype models account well for them; and (d) the recognition data suggest that controls use a single-comparison exemplar-memorization process more powerfully than amnesics. By pairing categorization based in prototypes with recognition based in exemplar memorization, the authors support and extend other recent accounts of cognitive performance that intermix prototypes and exemplars, and the authors reinforce traditional interpretations of the categorization-recognition dissociation in amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Level A in vivo-in vitro correlation: nonlinear models and statistical methodology

Some new nonlinear models for the relationship between the fraction of drug dose dissolved (absorbed) in vivo and that dissolved in vitro are described. The models are empirical in nature and are generalizations of the linear model that, at present, is the most commonly used model. The modeling approach is based on considering the time at which a drug molecule goes into solution (in vitro or in vivo) to be a random variable and relating the distribution functions using proportional odds, proportional hazards, and proportional reversed hazards models. The models are further extended by allowing the parameter that relates in vivo and in vitro to be a function of time. A statistical model for the data is developed and used as the basis for a statistical methodology for fitting these models. The methods are shown to be generalized linear mixed effects model (GLMM) methods. The models are fitted to some data sets, and the results demonstrate that these models have potential.     

Developmental stability of the relative influence of genes and environment on specific cognitive abilities during childhood.

Describes hierarchical multiple regression (HMR) model for analysis of cross-sectional data to examine developmental changes in the relative influence of genes and environment. The HMR model is advocated because it provides a test of significance for age changes without the loss of information and statistical power that results when continuous variables, such as age, are assigned to categories. This model was applied to 9 tests of specific cognitive abilities that were administered to 54 identical and 33 same-sex fraternal twin pairs whose ages ranged from 5 to 11 yrs. Results indicate that familial influences as well as the relative mixture of genetic and environmental influences on specific cognitive abilities remain stable during this fast-moving developmental era. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Why does monitoring fail in jargon aphasia? comprehension, judgment, and therapy evidence

Many people with jargon aphasia seem unaware of their speech disorder. The first section of this paper reports data from four subjects which indicate that self-monitoring can fail even when subjects' input skills are apparently adequate to detect their errors. Explanations for this dissociation have attributed monitoring failure to a deficit in auditory feedback, or to a resource limitation which prevents concurrent speaking and monitoring. Section 2 reports a series of naming and judging experiments with one of the subjects which rule out these explanations. These show that the subject can detect his neologisms when he is repeating, but not when he is naming. These results suggest that his monitoring difficulties arise when he is accessing phonology from semantics. Section 3 presents a study which supports this inference, since it shows that semantically focused intervention yields improvements in self-monitoring. It is concluded (1) that monitoring failure can arise from deficits within the production process which preclude comparison of actual with intended output, and (2) that this deficit is best explained within a connectionist model in which monitoring is performed by feedback mechanisms in the word production process.     

A contribution of cognitive decision models to clinical assessment: Decomposing performance on the Bechara gambling task.

The Bechara simulated gambling task is a popular method of examining decision-making deficits exhibited by people with brain damage, psychopathology, antisocial personality, or drug abuse problems. However, performance on this task is confounded by complex interdependencies between cognitive, motivational, and response processes, making it difficult to sort out and identify the specific processes responsible for the observed behavioral deficits. The authors compare 3 competing cognitive decision models of the Bechara task in terms of their ability to explain the performance deficits observed in Huntington's disease patients as compared with healthy populations and people with Parkinson's disease. The parameters of the best fitting model are used to decompose the observed performance deficit of the Huntington patients into cognitive, motivational, and response sources. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Toward an Alternative Representation for Disentangling Age-Associated Differences in General and Specific Cognitive Abilities.

Much of cognitive aging research concerns whether age-associated differences in various cognitive performances can be accounted for by general explanatory constructs or whether several specific processes are involved. Structural equation models have been proposed to disentangle general and specific age-associated differences in cognitive performance. This article demonstrates that existing methods that employ stepwise procedures run the risk of biasing results toward general resource accounts. An alternative model representation (i.e., the nested factor model) is proposed that affords simultaneous estimation of general and specific effects and is applied to data from the Berlin Aging Study. Using the nested factor model allowed the authors to detect that specific group factors explained 25% of the age-associated variance in addition to the general factor. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How shared are age-related influences on cognitive and noncognitive variables?

Several theories have suggested that age-related declines in cognitive processing are due to a pervasive unitary mechanism, such as a decline in processing speed. Structural equation model tests have shown some support for such common factor explanations. These results, however, may not be as conclusive as previously claimed. A further analysis of 4 cross-sectional data sets described in T. Salthouse, D. Hambrick, and K. McGuthry (1998) and T. Salthouse and S. Czaja (2000) found that although the best fitting model included a common factor in 3 of the data sets, additional direct age paths were significant, indicating the presence of specific age effects. For the remaining data set, a factor-specific model fit at least as well as the best fitting common factor model. Three simulated data sets with known structure were then tested with a sequence of structural equation models. Common factor models could not always be falsified-even when they were false. In contrast, factor-specific models were more easily falsified when the true model included a unitary common factor. These results suggest that it is premature to conclude that all age-related cognitive declines are due to a single mechanism. Common factor models may be particularly difficult to falsify with current analytic procedures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A meta-analysis of performance on emotion recognition tasks in Parkinson’s disease.

Individuals with Parkinson’s disease (PD) have shown deficits in the ability to recognize emotion. However, these results have been inconsistent. In addition, questions remain about whether any deficit in PD is secondary to depression and broader cognitive impairments, and the effects of stimulus modality, task type, and specific emotion remain unclear. A meta-analysis of 34 comparisons, using data from 1,295 individual participants, was conducted to (a) provide a reliable estimate of the magnitude of the purported deficit in emotion recognition and (b) examine the influence of several potential moderators of emotion recognition abilities in PD. Results show a robust link between PD and specific deficits in recognizing emotion, from both the face and the voice (overall effect size g = 0.52). The deficit extends across stimulus modalities and task types and is particularly acute with respect to negative emotions. Although this deficit does not appear to be secondary to comorbid depression or visuospatial impairments, the potential role of working memory constraints warrants further investigation. We highlight the potential implications of these findings for communication abilities in PD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory impairments in multiple sclerosis: Evidence from a dual-task paradigm.

The aim of this study was to investigate working memory in multiple sclerosis (MS) patients. To test the hypothesis that the central executive system (CES) of working memory is impaired, 36 MS patients were administered a dual-task paradigm in which a judgment of line orientation measure was performed concurrently with finger tapping, humming a melody, or reciting the alphabet. MS patients exhibited a significantly greater decrement in performance than controls during the more demanding dual-task conditions (concurrent humming or alphabet recitation) as compared with the single-task condition. Dual-task performance in MS patients correlated with performance on the Paced Auditory Serial Addition Test but not with other cognitive or clinical measures. The authors conclude that MS patients have a working memory deficit reflecting an impaired central executive system. Moreover, impairments in speed of information processing in MS patients are associated with this CES deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tandem mass spectrometry analysis of synthetic opioid peptide analogs

Five synthetic opioid peptides that were designed to have specific opioid receptor-binding properties were studied by low energy collision-induced dissociation (CID) tandem mass spectrometry (MS/MS). The MS/MS data are required for the analysis of those peptides in ovine plasma in a study to determine the placental transfer of the peptide to the fetus. The synthetic enkephalin-related peptides were: Tyr-D-Arg-Phe-Lys-NH2, (DALDA), N,N-diallyl-Tyr-Aib-Aib-Phe-Leu-OH, (ICI 174,864), Tyr-D-Thr-Gly-Phe-Leu-Thr, (DTLET), Tyr-D-Pen-Gly-Phe-D-Pen-OH, (DPDPE), and D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2, (CTAP). Liquid secondary ion mass spectrometry (LSIMS) was used for sample desorption-ionization, and a hybrid (E1BE2qQ) tandem mass spectrometer was used to collect the product-ion spectra. A protonated molecule ion, [M + H]+, was observed for each peptide. Amino acid sequence-determining fragment ion were produced by CID and collected by MS/MS for the three linear peptides, and also for the two disulfide-bond-containing peptides in their unreduced and dithiothreitol (DTT)-reduced forms. The detection level for the [M + H]+ ion of DTLET was ca. 3 pmol; and the stabilities of the CTAP and ICI analogs in plasma were studied.     

Model Validation for Bridge-Road-Vehicle Dynamic Interaction System

The dynamic response of highway bridges subjected to moving truckloads has been observed to be dependent on (1) dynamic characteristics of the bridge; (2) truck configuration, speed, and lane position on the bridge; and (3) road surface roughness profile of the bridge and its approach. Historically, truckloads were measured to determine the load spectra for girder bridges. However, truckload measurements are either made for a short period of time [for example, weigh-in-motion (WIM) data] or are statistically biased (for example, weigh stations) and cost prohibitive. The objective of this paper is to present results of a 3D computer-based model for the simulation of multiple trucks on girder bridges. The model is based on the grillage approach and is applied to four steel girder bridges tested under normal truck traffic. Actual truckload data collected using a discrete bridge WIM system are used in the model. The data include axle loads, truck gross weight, axle configuration, and statistical data on multiple presence (side by side or following). The results are presented as a function of the static and dynamic stresses in each girder and compared with code provisions for dynamic load factor. The study provides an alternate method for the development of live-load models for bridge design and evaluation.     

Psychological Mechanisms of Medically Unexplained Symptoms: An Integrative Conceptual Model.

Theories of medically unexplained illness based on the concepts of dissociation, conversion, and somatization are summarized. Evidence cited in support of these theories is described and the conceptual strengths and shortcomings of each approach are considered. It is argued that each of these approaches adds to the understanding of unexplained illness but that none is able to provide a comprehensive explanation of the phenomenon. An integrative conceptual model of unexplained illness based on cognitive psychological principles is then presented. This model attempts to combine existing theoretical approaches within a single explanatory framework, extending previous theory by explaining how compelling symptoms can exist in the absence of organic pathology. The clinical and empirical implications of the model are then considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship between cognitive deficits and everyday functional activities in multiple sclerosis.

Considerable evidence indicates that cognitive dysfunction and impairments in everyday life activities are common in multiple sclerosis (MS). However, the relationship between these cognitive and functional deficits has not been thoroughly investigated. The purpose of this study was to examine the role of cognitive dysfunction in the functional status of individuals with MS. Participants were 74 adults with MS and 35 healthy comparison participants (HCs) who underwent neuropsychological testing and completed the Executive Functions Performance Test (EFPT; Baum, Morrison, Hahn, & Edwards, 2003), an objective measure of everyday life activities. Between-groups comparisons and correlational analyses were conducted to examine the relationship between cognition and functional capacity. Significant differences in EFPT performance were revealed between individuals with MS with and without cognitive impairment and HCs. In individuals with MS, performance on cognitive constructs was related to performance on the EFPT. Furthermore, a linear regression model comprised of indices of cognitive functioning explained a significant portion of the variance in everyday life activities. Findings suggest that individuals with and without cognitive impairment differ in functional status and that aspects of cognition are predictive of functional status in MS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Patterns of dissimilarities among instrument models in measuring PO2, PCO2, and pH in blood gas laboratories

STUDY OBJECTIVES: To ascertain the degree of dissimilarities among blood gas and pH analyzer models of the same and different manufacturers in measurement of PO2, PCO2, and pH using fluorocarbon containing emulsion (FCE) proficiency testing material. DESIGN: Statistically and graphically analyze data from six recent proficiency testing surveys for the 20 more frequently used models of analyzers. SETTING AND PARTICIPANTS: Over a 2-year period, approximately 900 participants from blood gas laboratories in the United States analyzed similar ampules from each of 30 lots. MEASUREMENTS AND RESULTS: Both graphic and statistical comparisons were used to demonstrate differences between manufacturers. For each of the four major manufacturers, comparisons revealed statistically significant differences not only for PO2, but also for PCO2 and pH. Additionally, comparison models within each of the three manufacturers (those with multiple models and > 15 instruments per model represented) disclosed statistically significant dissimilarities among models for each analyte in 115 of 153 model pairings. Previously reported tonometered blood differences among analyzer models for PO2 are qualitatively similar to the differences found in these same models in this FCE study. Model differences are important in research studies and may be clinically important in deciding abnormality, selecting oxygen therapy, or the treatment of patients with respiratory failure or severe respiratory alkalosis. CONCLUSIONS: To minimize the likelihood of misleading clinicians, laboratory directors should consider the degree of dissimilarity among blood gas analyzer models in current use and when changing instrumentation.