SEARCH · PubMed Health

Results for “processing speed”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources

PubMed1997

Neuropsychology of chronic fatigue syndrome: a critical review.

This article provides a comprehensive and critical review of the neuropsychological and related literature on chronic fatigue syndrome (CFS). Despite the methodological limitations observed in several studies, some consistent findings are noted. The most consistently documented neuropsychological impairments are in the areas of complex information processing speed and efficiency. General intellectual abilities and higher order cognitive skills are intact. Emotional factors influence subjective report of cognitive difficulty, whereas their effect on objective performance remains uncertain. Although the neuropathological processes underlying cognitive dysfunction in CFS are not yet known, preliminary evidence suggests the involvement of cerebral white matter. Directions for future research are outlined.

Fatigue Syndrome, Chronic↗

PubMed1993

White matter changes in healthy elderly persons correlate with attention and speed of mental processing.

OBJECTIVE: To evaluate the association between white matter changes (leukoaraiosis [LA]) seen on magnetic resonance imaging and cognitive functions. DESIGN: Survey of cohorts of neurologically healthy elderly subjects derived consecutively from a population-based random sample. SETTING: General community, the Helsinki (Finland) Aging Brain Study. SUBJECTS: Cohorts of neurologically healthy subjects aged 55, 60, 65, 70, 75, 80, and 85 years (n = 20, 18, 19, 18, 17, 17 and 11 subjects, respectively; total N = 120). MEASURES: Leukoaraiosis was rated in the periventricular areas (0 to 24) and the centrum semiovale (0 to 24); also, a total LA score was obtained (0 to 48). The neuropsychological test battery covered memory, verbal intellectual and constructional functions, language, speed and attention, and speed of mental processing, as well as simple psychomotor speed. RESULTS: Low age-related LA scores and deterioration of cognitive functions were obtained in the normal subjects. When controlling for age, we found that speed and attention, together with the speed of mental processing measured by the Trail Making A and the Stroop tests, correlated with the total LA score. However, there was wide variation between subjects. Comparing groups with and without LA proved the association of LA with Trail Making A time, Stroop test result (words/time and difference/time), and the compound score of speed and attention. Presence of periventricular LA was especially related to speed of mental processing. CONCLUSION: Leukoaraiosis could explain some of the intellectual impairment in the elderly, especially that of slowing of distinct motor and attentional functions, as well as slowing of mental processing. Mild LA in normal aged subjects could also signal brain at risk for further cognitive impairment.

Aged↗

PubMed1996

Application of neural networks to flow cytometry data analysis and real-time cell classification.

Conventional analysis of flow cytometric data requires that population identification be performed graphically after a sample has been run using two-parameter scatter plots. As more parameters are measured, the number of possible two-parameter plots increases geometrically, making data analysis increasingly cumbersome. Artificial Neural Systems (ANS), also known as neural networks, are a powerful and convenient method for overcoming this data bottleneck. ANS "learn" to make classifications using all of the measured parameters simultaneously. Mathematical models and programming expertise are not required. ANS are inherently parallel so that high processing speed can be achieved. Because ANS are nonlinear, curved class boundaries and other nonlinearities can emerge naturally. Here, we present biomedical and oceanographic data to demonstrate the useful properties of neural networks for processing and analyzing flow cytometry data. We show that ANS are equally useful for human leukocytes and marine plankton data. They can easily accommodate nonlinear variations in data, detect subtle changes in measurements, interpolate and classify cells they were not trained on, and analyze multiparameter cell data in real time. Real-time classification of a mixture of six cyanobacteria strains was achieved with an average accuracy of 98%.

Animals↗

PubMed1998

Visual search tasks: slowing of strategic and nonstrategic processes in the nonlexical domain.

Some investigators have argued that aging affects the slowing of processes in nonlexical tasks more than it does the slowing of processes in lexical tasks, but that within task domains, the slowing is identical. Other investigators have argued that even within nonlexical tasks there is differential slowing such that aging affects processing speed more in (nonlexical) coordinative tasks than it does in (nonlexical) sequential tasks. Perhaps, more finely still, there is a differential slowing in coordinative nonlexical tasks. Toward this end, latent models of general and process-specific slowing in coordinative nonlexical tasks were formulated for older adults. A visual search task was then used to test the two types of models. It was found that a latent model of process-specific slowing explained significantly more of the variability than a latent model of general slowing, indicating that there is a differential slowing of processes among coordinative tasks within the nonlexical domain. It was also discovered that the coordinative process most greatly affected was that of deciding to terminate the search when no target was present in the display, indicating together with other studies a possible difference in the slowing of strategic processes among both coordinative and sequential tasks within the nonlexical domain, but no difference in the slowing of nonstrategic processes.

Adult↗

PubMed1986

Image processing--principles and its future applications in reconstructive and aesthetic plastic surgery.

Although the great importance of the visual aspect to medical science, and plastic surgery in particular, is beyond doubt, the utilization of image systems for transmission, storage, and processing of images is not at all widespread. The main reason for this phenomenon is that owing to the high complexity of imaging-related equipment, in comparison with other means such as audio equipment (telephone, tape recorders, and so on), more complicated systems are required, including wider broadcasting channels, much larger storage capacities, and higher processing speeds than are available now. Except for extensive research and development activities in the universities, research institutes, and military organizations, the large potential of the artificial visual aspect is not commonly utilized. In the future, efficient utilization of image processing capabilities in the service of plastic surgery will be achieved by the emerging capabilities for many complicated procedures. These include huge image data base processing, automatic detection of pathologic cases by enhancement of details and recognition of patterns, accurate measurements of the changes and distortions in the processed images, prediction of results to allow planning of treatment, simulation, and training on computerized cases. The new capabilities also include visual control of robotic arms for complicated operations, better audio-visual communication between faraway clinics and medical centers via sophisticated teleconferencing systems--which will save traveling expenses and time and will enable the updating of medical information--and many more applications that will be developed when the basic equipment becomes an integrated part of the clinics and plastic surgery departments. Future image processing will enhance the visual aspect in the plastic surgeon's work and will enable the doctor to expand his or her professional capabilities.

Automation↗

PubMed1997

Examination of age-related deficits on the Wisconsin Card Sorting Test.

Adult age differences in Wisconsin Card Sorting Test (WCST) measures were examined before and after statistical control of age-related differences in measures of feedback usage, working memory, and perceptual-comparison speed. The proportion of age-related variance associated with a summary measure of WCST performance was greatly reduced after controlling for measures of feedback usage, working memory, and perceptual-comparison speed. Furthermore, the age-related variance associated with the feedback-usage measure was reduced after controlling for working memory and perceptual-comparison speed measures. These results are consistent with the idea that age-related performance differences in the WCST are partially mediated by adult age differences in feedback usage and that age differences in feedback usage are mediated by age differences in working memory, which are in turn-mediated by age-related reductions in processing speed, indexed by measures of perceptual-comparison speed.

Adolescent↗

PubMed1986

An automated technique for analysis of current transitions in multilevel single-channel recordings.

Detailed kinetic studies of ion channel gating are best carried out using the patch-clamp technique which permits the measurement of the ionic current through individual channels. Typical patch-clamp recordings show the current signal, in the form of a sequence of rectangular pulses (analogous to a random telegraph signal), riding on slow baseline drift, partially obscured by high-frequency noise and distorted by filtering. In order to analyze such recordings, we have developed a set of interactive Pascal programs based on a feature-detection algorithm capable of identifying current transitions in multiple-channel recordings in the presence of substantial levels of noise and drift. Software operation is largely automated but includes provisions for examination and correction of the output. The software was optimized and systematically evaluated using simulated data with variable amounts of noise and drift. Results indicate that satisfactory performance is obtained for signal-to-noise ratio as low as four even with uncommonly large baseline drift. Steady-state processing speeds varied from 1,000 to 4,000 samples per second depending on data complexity.

Automation↗

PubMed1998

Working memory deficits of reading disabled children.

Aims of the study were to investigate the specificity of reading disabled childrens deficits in working memory capacity and to pursue whether their deficits could be accounted for by deficient processing or impairments in verbal short-term storage capacity. A group of 10-year-old reading disabled children was compared with two groups of normal reading children, matched for chronological age and reading age, respectively. Measures for working memory capacity, short-term capacity and processing speed related to the language and to the numerical domain were administered. Results indicated that reading disabled children performed worse on all measures of working memory capacity, irrespective of the domain which these measures reflected. Their poorer performance could neither be explained by inefficient processing nor to their deficits in verbal short-term storage capacity. Reading disabled children seem to have a general lack of capacity for the concurrent processing and storage of verbal information.

Child↗

PubMed1998

Relation of task switching to speed, age, and fluid intelligence.

Two studies were conducted to investigate whether a meaningful task-switching construct could be identified and, if so, to determine how it was related to measures of higher order cognition and to adult age. Both studies revealed that measures of task switching were moderately correlated across different combinations of tasks and that a switching construct could be distinguished from a construct reflecting processing speed. The results of the 2nd study revealed that although the task-switching construct was related to age and to measures of episodic memory, inductive reasoning, and spatial visualization, most of the relations between the switching construct and both age and other measures of cognition were shared with other variables.

Adolescent↗

PubMed1998

An automated hydrodynamic process for controlled, unbiased DNA shearing.

An automated, inexpensive, easy-to-use, and reproducible technique for controlled, random DNA fragmentation has been developed. The technique is based on point-sink hydrodynamics that result when a DNA sample is forced through a small hole by a syringe pump. Commercially available components are used to reduce the cost and complexity of the instrument. The design is optimized to reduce the volume of sample required and to speed processing time. Shearing of the samples can be completely automated by computer control. Ninety percent of sheared DNA fragments fall within a twofold size distribution that is highly reproducible. Three parameters are critical: the flow geometry, the flow rate, and a minimum number of iterations. Shearing is reproducible over a wide range of temperatures, DNA concentrations, and initial DNA size. The cloning efficiency of the sheared DNA is very good even without end repair, the distribution of assembled sequences is random, and there is no sequence bias at the ends of sheared fragments that have been cloned. The instrument, called the Point-sink Shearer (PtS), has already been exported successfully to many other laboratories.

Automation↗

PubMed1999

Processing lexically embedded spoken words.

A large number of multisyllabic words contain syllables that are themselves words. Previous research using cross-modal priming and word-spotting tasks suggests that embedded words may be activated when the carrier word is heard. To determine the effects of an embedded word on processing of the larger word, processing times for matched pairs of bisyllabic words were examined to contrast the effects of the presence or absence of embedded words in both 1st- and 2nd-syllable positions. Results from auditory lexical decision and single-word shadowing demonstrate that the presence of an embedded word in the 1st-syllable position speeds processing times for the carrier word. The presence of an embedded word in the 2nd syllable has no demonstrable effect.

Adult↗

PubMed1992

Cognitive impairment following closed head injury.

Cognitive impairments are usually the most disabling sequelae of CHI. The earliest stage of recovery from moderate to severe closed head injury is a period of PTA that typically includes memory loss for events preceding and surrounding the injury and memory loss for events occurring since the injury. Following resolution of PTA, deficits may be present in a number of cognitive domains. Memory and attention/information processing speed and efficiency are typically the cognitive domains most severely affected by head injury. Intellectual, language, and perceptual skills tend to be relatively preserved. Neurologic variables such as pupillary reactivity and worst GCS score are prognostic of cognitive impairment at 1 to 2 years postinjury. Following mild head injury, impairments of memory and information processing may be apparent within the first week of recovery. These deficits usually resolve in 1 to 3 months, although chronic complaints persist in a minority of individuals. The long-term cognitive effects of CHI are typically more severe for younger children than older children. Neuropsychologic assessment provides an objective way to measure the presence and severity of cognitive impairment.

Adult↗

PubMed1994

Smoking and Raven IQ.

Nicotine has recently been shown to enhance measures of information processing speed including the decision time (DT) component of simple and choice reaction time and the string length measure of evoked potential waveform complexity. Both (DT and string length) have been previously demonstrated to correlate with performance on standard intelligence tests (IQ). We therefore hypothesised that nicotine is acting to improve intellectual performance on the elementary information processing correlates of IQ. In the current experiment we tested this hypothesis using the Raven Advanced Progressive Matrices (APM) test. APM scores were significantly higher in the smoking session compared to the non-smoking session, suggesting that nicotine acts to enhance physiological processes underlying performance on intellectual tasks.

Adolescent↗

PubMed1984

Effects of methylphenidate (Ritalin) on information processing in hyperactive children.

The effect of methylphenidate on information-processing efficiency was studied in 12 hyperactive, nonretarded children. Performance on six efficiency tasks (Posner Letter Matching, Reaction Time, Memory Search, Category Verification, Item Identification, and Word-Span) and a general measure of on-task behavior were compared for children receiving methylphenidate or a placebo. The median drug dosage was .38 mg/kg, and it was ingested 1 1/2 hours prior to testing. Children blind to the drug-placebo condition were tested on 4 days. In general, methylphenidate-related improvements in attention to on-task behaviors were found. An overall analysis of processing speed suggested that methylphenidate improved efficiency. Methylphenidate significantly decreased reaction times to simple and complex stimulus arrays; differences due to the drug remained even when on-task attentive behaviors were statistically removed. Significantly fewer identification errors occurred on the Posner task in the methylphenidate condition. Results indicated that methylphenidate improved general attentional behaviors and positively influenced processes that define perceptual efficiency.

Adolescent↗

PubMed1983

Age, presentation rate, and the effectiveness of structural and semantic recall cues.

To replicate the results of research on age-related differences in the effectiveness of structural and semantic memory cues, 18 young, 18 middle-aged, and 18 elderly adults recalled three 20-item lists aided by category labels, or the initial two letters of each word, or no cues. Lists were presented at 1.5 or 4 sec presentation rates to evaluate the effects of changes in processing speed on age-related trends in cue effectiveness. Semantic cues were most effective in improving recall at all three age levels; structural cues produced intermediate levels of recall facilitation. There was no indication of reduced effectiveness of semantic cues with increases in age and presentation rate, suggesting factors other than age-related changes in the depth of processing are responsible for developmental differences in memory.

Adult↗

PubMed1992

Vision, aging, and driving: the problems of older drivers.

Although there are well-recognized declines in visual functioning with age, their contribution to the problems of older persons on tasks in the natural environment, including driving, are largely unknown. Adults ranging in age from 22-92 years were surveyed in regard to their visual difficulties when driving and performing everyday tasks. The visual problems of drivers increased with age along five different visual dimensions: unexpected vehicles, vehicle speed, dim displays, windshield problems, and sign reading. Several of the age-related visual problems that were reported appear to be related to the types of automobile accidents more common among older drivers. The study also replicated the findings from an earlier investigation of non-driving tasks that showed visual declines with age on five dimensions: visual processing speed, light sensitivity, dynamic vision, near vision and visual search. These findings indicate promising areas of research regarding the effects of visual aging on tasks in the natural environment.

Adult↗

PubMed1988

Anterograde and retrograde amnesia in patients with chronic progressive multiple sclerosis.

The performance of 38 patients with chronic progressive multiple sclerosis was compared with that of 26 age- and education-matched controls on a battery of tests of information-processing speed, verbal fluency, naming, egocentric perception, and anterograde and remote memory. Although there were marked differences in the extent and severity of cognitive disturbance among individual patients, as a group they were impaired compared with controls on all measures. Deficits were most striking on the Symbol-Digit Modalities Test and the verbal fluency measures, tests that require rapid information processing. More than 75% of the patients scored below the tenth percentile for controls on the Symbol-Digit Modalities Test, while 61% scored below the tenth percentile on verbal fluency. Memory disturbances were also common. More than 45% of the patients scored below the tenth percentile. The proportion of impaired patients was quite similar for anterograde and remote memory tests and for recall and recognition procedures. The pattern of memory disturbance and slowed information processing resembled deficits generally observed in subcortical dementias, such as Huntington's disease, but in addition, the patients with multiple sclerosis showed naming difficulties that are usually associated with cortical dementias, such as Alzheimer's disease.

Adult↗

PubMed1989

Use of a neural net computer system for analysis of flow cytometric data of phytoplankton populations.

Flow cytometry has been used over the past 5 years to begin detailed exploration of the distribution and abundance of picoplankton in the oceans. Light scattering and fluorescence measurements on individual plankton cells in seawater samples allow construction of population signatures from size and pigment characteristics. The use of "list mode" data has made these studies possible, but on-shore analysis of copious data does not permit on-site reexamination of important or unexpected observations, and overall effort is greatly handicapped by data analysis time. Here we describe the application of neural net computer technology to the analysis of flow cytometry data. Although the data used in this study are from oceanographic research, the results are general and should be directly applicable to flow cytometry data of any sort. Neural net computers are ideally suited to perform the pattern recognition required for the quantitative analysis of flow cytometry data. Rather than being programmed to perform analysis, the neural net computer is "taught" how to analyze the cell populations by presenting examples of inputs and correct results. Once the system is "trained," similar data sets can be analyzed rapidly and objectively, minimizing the need for laborious user interaction. The neural network described here offers the advantages of 1) adaptability to changing conditions and 2) potential real-time analysis. High accuracy and processing speed near that required for real-time classification have been achieved in a software simulation of the neural network on a Macintosh SE personal computer.

Computer Systems↗