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PubMed1993

Effects of allergy season on mood and cognitive function.

The study was conducted to evaluate the effects of having allergic reactions (ie, being in allergy seasons without taking medications) on: (1) speed of cognitive processing, (2) psychomotor speed, (3) ability to sustain attention, (4) verbal learning and memory, and (5) mood. Subjects (ten atopic, eight control) were given a neuropsychologic test and mood rating battery in an A-B-A design ie, in, out of, and in allergy seasons. Only atopic subjects exhibited declines in verbal learning, slower decision-making and psychomotor speed on both simple and choice reaction time tests, and lower positive affect during their allergy seasons in comparison to out of allergy seasons. Atopic subjects did not demonstrate declines in ability to sustain attention. Biochemical mechanisms may cause these changes.

Adult↗
PubMed2006

Reduction in the motion coherence threshold for the same direction as that perceived during adaptation.

When a stimulus of equally spaced parallel lines is displaced slightly in a direction perpendicular to the lines, low-speed motion toward the displacement direction can be perceived. Such a stimulus embodies both a low-speed and a high-speed component in opposite directions. The dominance of the former would result in the perception of low-speed motion. To see how the unperceived high-speed component is processed by the visual system, I measured coherence thresholds for random-dot test-motion with and without prior adaptation to the low-speed motion of the equally spaced parallel lines. The results depended on the test speeds. At low speeds, the coherence thresholds for the same direction as that perceived during the adaptation phase increased and the coherence thresholds for the opposite direction decreased. At high speeds, the same adaptation resulted in an opposite effect. The threshold reduction for high-speed motion in the same direction as that perceived during the adaptation phase and the threshold elevation in the opposite direction might be due to adaptation of a high-speed processing channel to the high-speed component that was not perceived but was nevertheless detected.

Adaptation, Ocular↗
PubMed2001

Intact implicit learning in schizophrenia.

OBJECTIVE: Schizophrenia impairs performance on explicit, but not implicit, memory tasks, indicating that conscious awareness at retrieval is a critical determinant of impaired memory. The authors investigated implicit learning, i.e., knowledge acquisition in the absence of conscious awareness, in patients with schizophrenia. METHOD: An artificial grammar learning task was used to assess implicit learning in 48 patients with schizophrenia and 24 healthy comparison subjects. The subjects were first presented with letter strings that were generated according to the rules of a finite-state grammar paradigm. They were then required to indicate whether new letter strings were "grammatical," depending on whether or not the strings corresponded to the rules. IQ, working memory, explicit memory, verbal fluency, and speed of processing were also assessed. RESULTS: Patients performed significantly worse than the comparison subjects on cognitive tasks that assessed episodic memory, verbal fluency, working memory, and speed of processing. In contrast, patients classified as being correct more grammatical than nongrammatical letter strings, and the magnitude of the difference was similar to that observed in healthy comparison subjects. CONCLUSIONS: Implicit learning, as assessed with an artificial grammar learning task, is intact in patients with schizophrenia. Conscious awareness might be a critical determinant of memory impairment both at encoding and at retrieval.

Adult↗
PubMed1984

Explososcan: a parallel processing technique for high speed ultrasound imaging with linear phased arrays.

The data acquisition rate in medical ultrasonic imaging devices is limited by the acoustic propagation velocity in the tissues. Typically in such machines the image lines are produced sequentially one line per transmitted pulse. A parallel processing scheme has been implemented which enables the data acquisition rate to increase by a factor of four through the simultaneous acquisition of four B-mode image lines from each individual broadened transmit pulse. The higher data rate can be used to increase the image frame rate to produce independent images that can be averaged in the image frame to reduce noise, or to produce a conventional image at standard video frame rates while reducing patient exposure. Alternatively, the field of view can be increased over that of a normal scan without sacrificing frame rate. These advantages are achieved with little reduction in the measured resolution. The design and performance of this device are described. A sample in vivo image is included.

Acoustics↗
PubMedDate not supplied

Are changes in sensory disability, reaction time, and grip strength associated with changes in memory and crystallized Intelligence? A longitudinal analysis in an elderly community sample.

BACKGROUND: Little is known about predictors of cognitive changes in the elderly. Sensory disability, grip strength, and speed of processing have been established as associates of cognitive performance in cross-sectional studies. However, it is not known whether changes in these predictor variables are associated with changes in cognitive functioning. OBJECTIVES: (1) to examine the relationship between initial level of three predictor variables - speed of processing, sensory disability, and grip strength - and changes in memory and crystallized intelligence (CIQ); (2) to examine the relationships between change in grip strength, cognitive speed, and sensory disability and changes in memory and CIQ, and (3) to investigate these relationships with the effects of age and sex statistically removed. METHODS: Cognitive ability was assessed in two domains: CIQ (3 tests) and memory (3 tests) measured on two occasions approximately three and a half years apart in a large community sample (n = 425; mean age = 75.8, range 70-93 years). Repeated-measures Anova was used to analyze descriptive data. Latent-change models were used to examine structural relationships between constructs. RESULTS: Initial levels of reaction time or grip strength did not predict rate of change on memory tasks. Changes in grip strength, speed, and memory correlated moderately, suggesting that these variables have some tendency to move together over time. Sensory disability correlated with age but not with change in speed, grip, memory, or CIQ. These relationships held across the age range studied after adjustment for age and sex. CONCLUSIONS: The findings are consistent with the action of a common causal mechanism underlying changes in speed, grip, and memory. A number of methodological caveats arise from our analysis. Cross-sectional and longitudinal data sets yield different interpretations about the basic component associates of cognitive performance.

Aged↗
PubMed1999

Echo decorrelation estimated from signal powers.

Volume flow can be estimated from the decorrelation of radiofrequency (RF) intravascular ultrasound signals. The method is based on a rather time-consuming process that measures the decorrelation slope from a time signal sequence. To improve the speed of flow processing, a more efficient way of estimating the flow velocity from the ratio between the power of the temporal averaged signal and the mean signal power is described in this paper. The relationship between the signal power-ratio index and the decorrelation slope was analyzed and tested using computer-simulated data. Volumetric flow data obtained with the power-ratio method were compared to those derived from the decorrelation slope in five patients. Results of the comparison studies indicate that no significant differences in flow measurements were found between the two methods, but the power-ratio method is able to improve the processing speed significantly.

Blood Flow Velocity↗
PubMed1997

Meta-analyses of age-cognition relations in adulthood: estimates of linear and nonlinear age effects and structural models.

A meta-analysis was conducted on 91 studies to derive a correlation matrix for adult age, speed of processing, primary-working memory, episodic memory, reasoning, and spatial ability. Structural equation modeling with a single latent common cognitive factor showed that all cognitive measures shared substantial portions of age-related variance. A mediational model revealed that speed of processing and primary-working memory appear to be important mediators of age-related differences in the other measures. However, not all of the age-related influences were mediated. An examination of quadratic age effects and correlational patterns for subsamples under and over 50 years of age revealed that (a) negative age-cognition relations were significant for the 18- to 50-year-old sample and (b) the age-related decline accelerated significantly over the adult life span for variables assessing speed, reasoning, and episodic memory.

Adult↗
PubMed2004

Cognitive impairment in relapsing and primary progressive multiple sclerosis: mostly a matter of speed.

Based on the assumption that cognitive impairment in MS is consistent with subcortical dementia, a battery of neuropsychological tests was assembled that included measures of executive function (Tower of London and Wisconsin Card Sorting Test), verbal learning and memory (a paired associates learning test), and speeded information processing (Stroop Color Word Interference Test). The battery was administered to patients with relapsing and primary progressive MS and to healthy controls. Differences between patients and controls occurred on several of the measures. However, when differences with respect to fatigue and depression were statistically controlled, the only differences that remained significant involved measures relating to the speed of information processing. Patients performed more slowly than controls, with the disparity being greater for relapsing patients than for those with primary progressive disease. The slowing was evident on measures of automatic as well as controlled processing and regardless of whether speed was an explicit feature of successful performance or recorded unobstrusively while the patient concentrated on planning a correct solution to a problem. Parallels were noted between cognitive slowing associated with MS and that of normal aging.

Adult↗
PubMed1990

Assessment of AIDS-related cognitive changes: recommendations of the NIMH Workshop on Neuropsychological Assessment Approaches.

This article presents an extended (7-9 hours) and a brief (1-2 hours) battery designed to evaluate early cognitive changes associated with seropositive, asymptomatic persons. The battery was recommended by an NIMH Workgroup which was guided by 10 principles in its development. The domains assessed by the battery are: (1) Indicators of Premorbid Intelligence; (2) Attention; (3) Speed of Processing; (4) Memory; (5) Abstraction; (6) Language; (7) Visuoperception; (8) Constructional Abilities; (9) Motor Abilities; and (10) Psychiatric Assessment. Although the battery assesses a wide range of psychological functioning, specific emphasis has been placed on divided and sustained attention as well as speed of processing and retrieval from working and long-term memory. Descriptions of both the traditional clinical tests and tasks used in cognitive psychology are provided. Although the Workgroup strongly recommends the use of the extended battery in order to ensure the most sensitivity, it recognizes that there may be situations in which this is not possible. In order to increase the likelihood that neuropsychological tests will identify neurologically affected CDC Stage II and III seropositive individuals, the Workshop recommends that each patient's protocol be rated by two trained neuropsychologists using the same clinical criteria. The Workgroup also recommends that a concerted effort be made to incorporate data from the extended and the brief batteries in some central data bank.

AIDS Dementia Complex↗
PubMed1998

The APOE epsilon4 allele is associated with decline on delayed recall performance in community-dwelling older adults.

OBJECTIVE: This study investigated whether the Apolipoprotein (APOE) epsilon4 allele was associated with cognitive decline in community-dwelling older adults. DESIGN: Longitudinal cognitive performance of older adults with the epsilon3/epsilon4 genotype was compared with that of older adults with the epsilon3/epsilon3 genotype. SETTING: Aging Clinical Research Center, Stanford University. PARTICIPANTS: One hundred community-dwelling older adults were recruited from a pool of 531 individuals who had participated in a memory training study 4 to 5 years earlier. These individuals were concerned about their memory functioning and were recruited through newspaper advertisements and contacts with local senior centers. The 100 individuals who agreed to participate in the follow-up investigation were between 59 and 95 years of age. MEASUREMENTS: At both baseline and follow-up, subjects were administered a battery of seven cognitive tests that examined verbal and spatial memory, attention, speed-of-processing, and language abilities. APOE genotype was determined at follow-up. RESULTS: Individuals with the epsilon3/epsilon4 APOE genotype were significantly younger than individuals with the APOE epsilon3/epsilon3 genotype. No significant differences were observed between the two groups on measures of attention, speed-of-processing, vocabulary, immediate verbal memory, and immediate spatial memory. However, those older adults with the epsilon3/epsilon4 genotype exhibited significantly greater decline in performance on delayed recall of verbal material than did those with the epsilon3/epsilon3 APOE genotype. CONCLUSION: These findings are consistent with previous studies, which suggest that the APOE epsilon4 allele predicts decline on measures of delayed recall.

Adult↗
PubMed1997

Information processing through the first year of life: a longitudinal study using the visual expectation paradigm.

This Monograph uses a developmental function approach to describe age-related change and individual differences in infant information processing during the first year of life. The Visual Expectation Paradigm (VExP) is used to measure speed of information processing, response variability, and expectancy formation. Eye-movement reaction times and anticipatory saccades were gathered from 13 infants assessed monthly from 2 to 9 months and then again at 12 months. Analysis of response patterns demonstrated the applicability of the paradigm throughout the age range studied. Converging operations strongly indicate that the traditional estimate of the minimum time required for infants to initiate a saccade to a peripheral stimulus may be as much as 100 milliseconds (ms) too long. Moreover, the newly estimated minimum of 133 ms does not appear to change during the 2-12-month period. Reanalysis of the present data and past research reveals that the new, shorter minimum reaction time is unlikely to affect findings based on mean reaction time. However, using the traditional minimum reaction time will inflate estimates of percentage anticipation, especially in infants older than 5 months. Group and individual growth curves are described through quantitative models of four variables: reaction time, standard deviation of reaction time, percentage anticipation, and anticipation latency. Developmental change in reaction time was best described by an asymptotic exponential function, and evidence for a local asymptote during infancy is presented. Variability in reaction time was found to decline with age, independent of mean reaction time, and was best described by a polynomial function with linear and quadratic terms. Anticipation showed little lawful change during any portion of the age span, but latency to anticipate declined linearly throughout the first year. Stability of individual differences was strong between consecutive assessments of mean reaction time. For nonconsecutive assessments, stability was found only for the 6-12-month period. Month-to-month stability was inconsistent for reaction-time variability and weak for both anticipation measures. Analyses of individual differences in growth curves were carried out using random regressions for the polynomial models. The only significant individual difference (in growth curves) was found for reaction-time variability. Parameter estimates from the exponential models for reaction time suggested two or three developmental patterns with different exponential trajectories. This finding indicates that the strong form of the exponential growth hypothesis, which states that processing speed develops at the same rate for all individuals, does not hold for the first year of life. In the concluding chapter, Grice's Variable Criterion Model (Grice, 1968) is used to integrate three key findings: regular age changes in mean reaction time and variability but no age change in the minimum reaction time. It is argued that the rate of growth of sensory-detection information is developmentally constant during much of the first year but that age changes occur in the level and spread of the distribution of response threshold values. The unique strengths of the paradigm are discussed, and future directions are suggested for further developing the paradigm itself and for using it as a tool to study broad issues in infant cognition.

Eye Movements↗
PubMed2000

An examination of the efficacy of Ginkgo biloba extract EGb761 on the neuropsychologic functioning of cognitively intact older adults.

OBJECTIVES: Few investigations have examined the effectiveness of Ginkgo biloba extract for enhancing cognitive abilities in individuals with no history of significant neurocognitive dysfunction. The purpose of this research was to examine the relatively short-term (i.e., 6 weeks) efficacy of Ginkgo biloba extract EGb 761 on the cognitive functioning of cognitively intact persons over the age of 55 years via a diverse battery of neuropsychologic tests and measures. PARTICIPANTS: From the 48 cognitively intact participants between the ages of 55 and 86 years who initially enrolled in this study, 21 males and 19 females successfully completed the study's protocol and provided valid data sets. DESIGN: A 6-week, double-blind, fixed-dose, placebo-controlled, parallel-group experimental design was utilized. Participants were randomly assigned to either a Ginkgo biloba extract EGb 761 (180 mg/d) or placebo control group. To evaluate participants' cognitive and behavioral functioning, series of neuropsychological tests were administered to them prior to the initiation of the Ginkgo biloba extract/placebo therapy (i.e., pretreatment baseline) and again, just prior to the termination of the treatment regimen (i.e., after 6 weeks). RESULTS: Participants who received 180 mg of Ginkgo biloba extract EGb 761 daily for 6 weeks exhibited significantly more improvement on a task assessing speed of processing abilities (i.e., Stroop Color and Word Test color-naming task) by the end of treatment as compared to participants who received placebo. Trends favoring improved performances in the Ginkgo biloba group were also demonstrated in three of the four remaining tasks that involved a timed, speed of processing component, although they did not reach statistical significance. Furthermore, a significant relationship was found between the type of treatment (Ginkgo biloba extract or placebo) and participants' ratings of their overall abilities to remember. Specifically, more participants in the Ginkgo biloba extract group rated their overall abilities to remember by the end of treatment as "improved," as compared to the placebo group. In contrast, no significant differences were found between the Ginkgo biloba and placebo groups by treatment end on any of the four objective memory measures. CONCLUSIONS: Taken together, the findings from standardized neuropsychologic assessment and a subjective, self-report questionnaire suggested that relatively short-term (i.e., 6 weeks) utilization of Ginkgo biloba extract EGb 761 may prove efficacious in enhancing certain neurocognitive functions/processes of cognitively intact older adults.

Aged↗
PubMed2000

The effect of clozapine on the speed and accuracy of information processing in schizophrenia.

1. The study aimed to investigate the effects of clozapine on the speed and accuracy of information processing in patients with schizophrenia. Data are reported from 13 subjects with schizophrenia, treated with clozapine for 6.8 (+/- 1.8) months. 2. Reaction time and accuracy of target detection on a tone detection task were measured before and during clozapine treatment, and these results were compared with a matched control group. 3. Symptom severity and performance on three timed tests of cognitive function were also measured prior to clozapine treatment in the schizophrenia group, and these measures were repeated during treatment with clozapine. 4. Treatment with clozapine was found to significantly improve reaction time and the accuracy of target detection in patients with schizophrenia. Despite this improvement their performance remained significantly inferior to that of a matched control group. Both positive and negative symptoms improved with clozapine treatment, as did performance on the WAIS-R digit symbol substitution test. 5. Improved performance on the WAIS-R digit symbol substitution test correlated with reduction in negative symptoms, and faster reaction time showed some correlation with reduction in positive symptoms. 6. The results of this pilot study indicate that treatment with clozapine can produce limited improvement in cognitive function in schizophrenia.

Acoustic Stimulation↗
PubMed1994

Assessing believable deficits on measures of attention and information processing capacity.

The vulnerability of tests of sustained attention and speed of processing to faked deficits was evaluated by comparing the performances of normal controls, healthy subjects asked to simulate deficits, and patients with closed head injury on a simple auditory reaction-time task and on the PASAT. The results revealed that persons attempting to feign the effects of brain injury perform more poorly than non-malingerers on a simple reaction-time task and the PASAT. The reaction-time task, however, proved more effective than the PASAT at detecting dissimulation, accurately classifying about 76% of the subjects. This value reflects a respectable hit rate for three-group classification.

Journal Article↗
PubMed2006

Picking up speed in understanding: Speech processing efficiency and vocabulary growth across the 2nd year.

To explore how online speech processing efficiency relates to vocabulary growth in the 2nd year, the authors longitudinally observed 59 English-learning children at 15, 18, 21, and 25 months as they looked at pictures while listening to speech naming one of the pictures. The time course of eye movements in response to speech revealed significant increases in the efficiency of comprehension over this period. Further, speed and accuracy in spoken word recognition at 25 months were correlated with measures of lexical and grammatical development from 12 to 25 months. Analyses of growth curves showed that children who were faster and more accurate in online comprehension at 25 months were those who showed faster and more accelerated growth in expressive vocabulary across the 2nd year.

Child Language↗
PubMed1991

On age differences in processing variability and scanning speed.

This investigation examined adult age differences on a recognition memory taks for order information. Experiment 1 consisted of a modified memory-scanning task in which a memory set of four letters was presented in boxes. Subjects judged whether a subsequent probe letter was or was not transposed from its original presentation position. One block of primary memory trials (i.e., no distractor task) and one block of secondary memory trials (i.e., a 10-second distractor task) were used. Experiment 2 used basically the same task, except both blocks of trials were primary memory tasks, and acoustic similarity was manipulated. A processing variability model predicted that both experiments should show distance effects (i.e., transposing letters a distance of one box should result in more errors and/or longer reaction times than a transposition of two, or three boxes) for both right and left transposition directions. However, a generalized slowing model predicted that distance effects should only occur for left transpositions (because of left-to-right scanning order). The present data supported the processing variability model but not the generalized slowing model.

Adolescent↗
PubMed2005

Visual dysfunction in Parkinson disease without dementia.

OBJECTIVE: To determine the profiles of visual dysfunction and their relationship to motor and cognitive dysfunction and to disability in mild to moderate Parkinson disease (PD) without dementia. METHODS: Seventy-six independently living participants with mild to moderate PD and 161 neurologically normal older adults were studied using a comprehensive battery to assess visual acuity, contrast sensitivity (CS), visual speed of processing and attention, spatial and motion perception, visual and verbal memory, visuoconstructional abilities, executive functions, depression, and motor function. RESULTS: Participants with PD scored significantly worse on all tests of vision and cognition compared with normal elderly persons. Reduced CS contributed to deficits on tests of spatial and motion perception and attention in participants with PD. Impairments in visual attention and spatial perception predicted worse cognitive function. Worse performances on tests of visual speed of processing and attention, spatial and motion perception, visual construction, and executive functions correlated with measures of postural instability and gait difficulty (in the Motor section of the Unified Parkinson's Disease Rating Scale). Impairments in motor function, visual memory, mood, and executive functions predicted worse disability as measured by Schwab-England Activities of Daily Living Scale. CONCLUSIONS: Patients with mild to moderate Parkinson disease showed impaired visual perception and cognition compared with elderly control subjects. Visual dysfunction contributes to parkinsonian disability through its influences on cognition and locomotion.

Aged↗