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Results for “processing speed”

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PubMed1987

Electrodermal lability and simple reaction time.

Subjects identified as electrodermally labile or stabile (n = 10 per group) on the basis of non-specific electrodermal fluctuations and a trials-to-criterion measure of habituation were compared in a simple reaction time (RT) task that employed long, variable foreperiods (from 8 to 19 s). Labiles had significantly faster RTs across all foreperiods, but there were no differences in RT variability between the groups. Phasic heart rate responses recorded concurrently through the foreperiod showed a characteristic pattern of acceleratory and deceleratory activity, which was similar among both labiles and stabiles. The findings indicate that labiles and stabiles show a consistent difference in the speed of processing of a target imperative stimulus, which is not due to differences in response preparation processes. Overall, the results support the use of RT paradigms for evaluating individual differences in information-processing associated with electrodermal lability.

Adult↗

PubMed1994

Sub-millisecond coincidence detection in active dendritic trees.

Stimulations of a morphologically reconstructed cortical pyramidal cell suggest that the long, thin, distal dendrites of such a cell may be ideally suited for nonlinear coincidence-detection at time-scales much faster than the membrane time-constant. In the presence of dendritic sodium spiking conductances, such hypothetical computations might occur by two distinct mechanisms. In one mechanism, fast excitatory synaptic currents inside a thin dendrite create strong local depolarizations, whose repolarization--resulting from charge equalization--can be 100-fold faster than the membrane time-constant; two such potentials in exact coincidence might initiate a dendritic spike. In the alternate mechanism, dendritic sodium spikes which do not fire the soma nonetheless create somatic voltage pulses of millisecond width and a few millivolts amplitude. The soma may fire upon the exact coincidence of several of these dendritic spikes, while their strong delayed-rectifier currents prevent the soma from temporally summating them. The average firing rate of a compartmental simulation of this reconstructed cell can be highly sensitive to the precise (submillisecond) arrangement of its inputs; in one simulation, a subtle reorganization of the temporal and spatial distribution of synaptic events can determine whether the cell fires continuously at 200 Hz or not at all. The two cellular properties postulated to create this behavior--fast, strong synaptic currents and spiking conductances in the distal dendrites--are at least consistent with physiological recordings of somatic potentials from single and coincident synaptic events; further measurements are proposed. The amplitudes and decays of these simulated fast EPSPs and dendritic spikes can be quantitatively predicted by approximations based on dendritic properties, intracellular resistance, and transmembrane conductance, without invoking any free parameters. These expressions both illustrate the dominant biophysical mechanisms of these very transient events and also allow extrapolation of the simulation results to nearby parameter ranges without requiring further simulation. The possibility that cortical cells perform temporally precise computations on single spikes touches many issues in cortical processing: computational speed, spiking variability, population coding, pairwise cell correlations, multiplexed information transmission, and the functional role of the dendritic tree.

Action Potentials↗

PubMed1994

Harmonic generation in "non-linear" biological systems.

We describe a high performance, low frequency Fourier Transform based spectrum analyser, with design features particularly suited to the harmonic analysis of the non-linear amplitude transfer functions of various biological systems. A previous published method, using general purpose systems to produce reference and signal plus reference "power" spectra, was susceptible to ambiguous interpretation of results. Unlike that design, the present spectrometer derives quantitative complex voltage (amplitude and phase) harmonics of sampled voltage data, maintaining potentially important information. Based on the use of a basic IBM or compatible PC, it features high sensitivity, high speed data processing and large dynamic range, is compact, easy to use, flexible in operation and low in cost. Its precision current signal source eliminates harmonics generated at the drive electrodes from the measurement. Use of the instrument leads us to conclude that, contrary to previous assertions, no repeatable dielectric or conductive non-linearity is exhibited in the bulk cell suspensions tested under the field and frequency conditions reported.

Electric Impedance↗

PubMed2006

The useful field of view test: normative data for older adults.

The Useful Field of View test (UFOV) is increasingly used in clinical and rehabilitation settings. To date there have been no normative data for adjusted performance comparisons across demographically-similar, elderly peers. This study examined demographic and cognitive influences on the UFOV in a sample of 2759 participants (65-94 years of age). Performance was found to differ by age and education. Regression analyses examined the relative contributions of age, education, mental status, vision, and health to UFOV performance. All of these factors were found to significantly contribute to UFOV performance, with age accounting for the most variance and education accounting for the least. Normative tables for the UFOV by age and education are provided. These norms will allow researchers and clinicians to compare UFOV performance with similar peers and may help in identifying elderly persons who would benefit from speed of processing training.

Age Factors↗

PubMed2004

Predictive influence of phonological processing, morphological/syntactic skill, and naming speed on spelling performance.

This paper focuses on the predictive influence of phonological awareness, morphological/syntactic skill, and naming speed on spelling. The retrospective study correlated spelling performance in a group of 199 French-speaking children at the end of grade 2 with earlier capacities for phonemic manipulation, morphological/syntactic correction, and naming speed, assessed at the end of grade 1. The results are consistent with an integrative model that challenges the unitary phonological disorder hypothesis and confirmed that in French, as in other languages, naming speed is an independent predictor of reading performance.

Age Factors↗

PubMed2005

Symbol-string sensitivity and adult performance in lexical decision.

In this study of adult readers, we used a symbol-string task to assess participants' sensitivity to the position of briefly presented, non-alphabetic but letter-like symbols. We found that sensitivity in this task explained a significant proportion of sample variance in visual lexical decision. Based on a number of controls, we show that this relationship cannot be explained by other factors including: chronological age, intelligence, speed of processing and/or concentration, short term memory consolidation, or fixation stability. This approach represents a new way to elucidate how, and to what extent, individual variation in pre-orthographic visual and cognitive processes impinge on reading skills, and the results suggest that limitations set by visuo-spatial processes constrain visual word recognition.

Adult↗

PubMed2004

Approaching a consensus cognitive battery for clinical trials in schizophrenia: the NIMH-MATRICS conference to select cognitive domains and test criteria.

To stimulate the development of new drugs for the cognitive deficits of schizophrenia, the National Institute of Mental Health (NIMH) established the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative. This article presents an overview of decisions from the first MATRICS consensus conference. The goals of the meeting were to 1) identify the cognitive domains that should be represented in a consensus cognitive battery and 2) prioritize key criteria for selection of tests for the battery. Seven cognitive domains were selected based on a review of the literature and input from experts: working memory, attention/vigilance, verbal learning and memory, visual learning and memory, reasoning and problem solving, speed of processing, and social cognition. Based on discussions at this meeting, five criteria were considered essential for test selection: good test-retest reliability, high utility as a repeated measure, relationship to functional outcome, potential response to pharmacologic agents, and practicality/tolerability. The results from this meeting constitute the initial steps for reaching a consensus cognitive battery for clinical trials in schizophrenia.

Clinical Trials as Topic↗

PubMed2006

Aptamer therapeutics advance.

Aptamers are selected nucleic acid binding species with affinities and specificities for protein targets that rival those of monoclonal antibodies. Furthermore, aptamers have definite advantages over antibodies, in that they can be chemically synthesized and modifications can be introduced that improve their stabilities and pharmacokinetic properties. A number of aptamers against therapeutically important targets have shown efficacy in cell and animal models, and a handful of aptamers are now in clinical trials or are being used as drugs. Recent advances in selection technologies and a more thorough exploration of how to deliver nucleic acids to target cells and tissues should further speed the process of drug development.

Animals↗

PubMed2006

Development of starch-based pellets via extrusion/spheronisation.

A modified starch (high-amylose, crystalline and resistant starch) was evaluated as an alternative excipient to microcrystalline cellulose for pellets prepared via extrusion/spheronisation. Theophylline anhydrous (25%, w/w) was used as a model drug. A binder was necessary to obtain an acceptable yield and the addition of sorbitol improved the surface properties of the pellets. A surface response design with three formulation variables (binder, sorbitol and water level) and one process variable (spheronisation speed) was used to optimise the process and to evaluate pellet yield, sphericity (aspect ratio and two-dimensional shape factor, e(R)), size (mean Feret diameter), friability and disintegration properties. Mixer torque rheometry and solid-state NMR revealed a significant influence of sorbitol on wet mass consistency and pellet properties. A high pellet yield (>90%), acceptable sphericity (AR<1.2), low friability (<0.01%), fast disintegration (<10 min) and complete drug release in less than 20 min for all formulations, demonstrated the potential of this modified starch in formulations intended for extrusion/spheronisation.

Algorithms↗

PubMed2006

Design and implementation of a point-of-care computerized system for drug therapy in Stockholm metropolitan health region--Bridging the gap between knowledge and practice.

INTRODUCTION: Stockholm County Council is the largest health care provider in Sweden with an annual budget of US$ 5 billion and catering the needs of a metropolitan population of 2 million people. About 10% of health care costs are used on drugs. In 1996 Stockholm County Council decided to address the main problems associated with the process and the quality of drug prescribing. METHODS: A multiyear strategy was designed, including the establishment of a strong evidence-based organisation, Drug and Therapeutics Committees and editorial resources to adapt information to the IT-media and the development of the IT-architecture. The development and implementation of computerized tools such as a physician drug order entry system including decision support, a drug information website and electronic transmission of prescriptions were started in 1996. RESULTS: The implementation was slow at the point-of-care units. It took about 6 years before the implementation process gained speed. In September 2005 almost 1000 doctors could use the decision support system for prescribing drugs and more than 70% of all prescriptions were transmitted electronically in our region. CONCLUSIONS: The work with the strategy has shown that improvements in drug use can be accomplished by providing access to simple, rapid and safe electronic tools, but the information provided has to be associated with well-recognized regional and national expert organisations.

Delivery of Health Care↗

PubMed2005

The use of real-time RT-PCR (TaqMan) and post-ELISA virus release for the detection of Beet necrotic yellow vein virus types containing RNA 5 and its comparison with conventional RT-PCR.

Real-time RT-PCR (TaqMan) assays were developed for the specific detection of Beet necrotic yellow vein virus (BNYVV). The two assays designed were a broad-spectrum one that detected RNA 2 from all types and a second designed to detect types containing RNA 5. The assays were validated against a range of different isolates from Europe and the Far East. These real-time assays were compared to a conventional RT-PCR assay for the detection of RNA 5. Sensitivity comparisons showed that for the detection of RNA 5, TaqMan was 10,000 times more sensitive than the conventional RT-PCR assay. Further improvements were made to the test procedure by using post-ELISA virus release (VR), as an alternative to RNA extraction. This significantly increased the speed of processing samples and reduced the staff input required, allowing the TaqMan assay to be used routinely as part of an annual survey of UK field samples.

Beta vulgaris↗

PubMed2006

COMT genotype, gender and cognition in community-dwelling, older adults.

A common polymorphism (Val158Met) in the gene encoding for the catechol-O-methyltransferase (COMT) enzyme has been associated with differences in prefrontal cognitive function in schizophrenic patients and healthy adults. While several studies indicate that the Met allele is associated with better performance on measures of executive function, working memory and verbal fluency, results have been inconsistent. Furthermore, fewer studies have investigated this relationship in older adults, a group known to experience impairments in prefrontal cognitive functions. Additionally, findings vary according to the gender distribution of study participants. We examined whether COMT genotype interacted with gender to impact cognition in a cohort of 163 healthy, older adults. Memory, verbal ability and areas of prefrontal cognitive function, including attention, speed-of-processing, and executive function, were assessed. We found no significant association between COMT genotype and any cognitive measure. However, gender interacted with COMT genotype to impact cognitive performance. Males homozygous for the Val allele performed better than both the Val/Met and Met/Met groups on measures of delayed recall. Heterozygous women performed better than their homozygous counterparts on the measure of verbal ability. These findings suggest that gender may be an important variable in consideration of the impact of COMT on cognition. Further, when gender is taken into consideration, any negative impact of COMT genotype may extend to cognitive domains other than those associated with prefrontal regions.

Aged↗

PubMed2006

Neuropsychological sequelae of digital mobile phone exposure in humans.

The effect of electromagnetic fields from digital mobile phones (DMP) on cognitive functioning is an area receiving increased attention. This study compares the performance of 120 volunteers on 8 neuropsychological tests during real or sham exposure to a DMP set to maximum permissible radiofrequency power output. When results were adjusted for known covariates (gender, age, or education), several alterations at significance levels of p<0.05 were obtained. Of these, simple and choice reaction times (CRT) showed strong evidence of impairment. Further, performance on the Trail Making Task (TMT) improved, supporting the hypothesis that DMP radiofrequency emissions improve the speed of processing of information held in working memory.

Adult↗

PubMed2004

Identification of separable cognitive factors in schizophrenia.

One of the primary goals in the NIMH initiative to encourage development of new interventions for cognitive deficits in schizophrenia, Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS), has been to develop a reliable and valid consensus cognitive battery for use in clinical trials. Absence of such a battery has hampered standardized evaluation of new treatments and, in the case of pharmacological agents, has been an obstacle to FDA approval of medications targeting cognitive deficits in schizophrenia. A fundamental step in developing such a battery was to identify the major separable cognitive impairments in schizophrenia. As part of this effort, we evaluated the empirical evidence for cognitive performance dimensions in schizophrenia, emphasizing factor analytic studies. We concluded that seven separable cognitive factors were replicable across studies and represent fundamental dimensions of cognitive deficit in schizophrenia: Speed of Processing, Attention/Vigilance, Working Memory, Verbal Learning and Memory, Visual Learning and Memory, Reasoning and Problem Solving, and Verbal Comprehension. An eighth domain, Social Cognition, was added due to recent increased interest in this area and other evidence of its relevance for clinical trials aiming to evaluate the impact of potential cognitive enhancers on cognitive performance and functional outcome. Verbal Comprehension was not considered appropriate for a cognitive battery intended to be sensitive to cognitive change, due to its resistance to change. The remaining seven domains were recommended for inclusion in the MATRICS-NIMH consensus cognitive battery and will serve as the basic structure for that battery. These separable cognitive dimensions also have broader relevance to future research aimed at understanding the nature and structure of core cognitive deficits in schizophrenia.

Arousal↗

PubMed2006

Cognitive side effects of anti-epileptic drugs. The relevance in childhood epilepsy.

In recent years several new anti-epileptic drugs have been introduced, also for the treatment of childhood epilepsy. A major concern is their effect on learning and cognitive development. Testing the genuine effects on cognition of the anti-epileptic drugs is methodologically not easy. At this moment there are very few controlled trials that systematically examine the cognitive side effects of anti-epileptic drugs in childhood epilepsy. The available data indicate that the newer anti-epileptic drugs have a safe cognitive profile when prescribed correctly at the right dose and in monotherapy. Possible negative effects are mainly found for speed of processing and attention processes. As these processes are important instruments in every day learning and cognition, it is necessary to test these newer anti-epileptic drugs in well designed studies and in specific childhood epilepsy syndromes.

Anticonvulsants↗

PubMed2004

Developmental cognitive neuroscience: progress and potential.

Developmental cognitive neuroscience is an evolving field that investigates the relations between neural and cognitive development. Lying at the intersection of diverse disciplines, work in this area promises to shed light on classic developmental questions, mechanisms subserving developmental change, diagnosis and treatment of developmental disorders, and cognitive and neuroscientific topics traditionally considered outside the domain of development. Fundamental questions include: What are the interrelations between developmental changes in the brain (e.g. in connectivity, chemistry, morphology) and developmental changes in children's behavior and cognitive abilities (e.g. representational complexity, ability to sustain selective attention, speed of processing)? Why, and how, is learning enhanced during certain periods in development? How is our knowledge organized, and how does this change with development? We discuss preliminary investigations of such questions and directions for future work.

Aptitude↗

PubMed1991

Angioscopy. New developments in vascular surgery.

Angioscopy is not a new procedure, but it is one that has undergone recent changes as the effects of technological improvement are adapted to the surgical environment. Recent advances allow the use of angioscopy to change the way some surgeries are performed and has altered others to a great degree. If the procedure is done infrequently, it can take several months and more than a few cases to master the procedure and setup. Having a small team of six vascular nurses for four full-time vascular surgeons has helped speed this process in our institution. In some institutions, the role of the nurse described in this article is performed by the surgical resident or fellow. As we gained experience, breakdown time was reduced and setup was more efficient.

Endoscopy↗

PubMed1997

Lexical decision, visual hemifield and angle of orientation.

Varying the orientation of word or nonword target stimuli from 0 degree to 90 degrees in a lexical decision-visual hemifield task results in an increase in RT and a decrease in accuracy and d'. RVF superiority, as measured by d' was found at all orientations. RVF superiority, as measured by RT was only found for stimulation by words at orientations of 0 degree and 15 degrees. There was a significant bias to respond 'word' (log beta) only for stimulation of the RVF at orientations of 0 degree and 15 degrees. Under all other conditions, there was no significant response bias. A 'normal' (horizontal) presentation format seems to be necessary for the finding of a greater RVF bias to respond 'word' and for RVF superiority in speed of processing linguistic stimuli. However, a horizontal presentation format does not seem to be necessary for the RVF superiority in its capability to discriminate words from nonwords.

Adolescent↗