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PubMed1992

Neuropsychological assessment in MS: clinical, neurophysiological and neuroradiological relationships.

We assessed cognitive performance and its relationship with clinical and anatomic disease severity in MS with mild to moderate handicap; 34 definite MS and 18 healthy subjects matched for age and education were submitted to a neuropsychological test battery. Both groups were examined for anxiety. MS patients underwent magnetic resonance imaging examination. MS performed worse than controls on all WAIS-P subtests and had learning, short- and long-term verbal memory impairment. Cognitive deficits were not related to abnormal emotional states, but were found to be associated with attentional process and information-processing speed impairment. Cognitive impairment did not correlate with severity of physical disability. The most severe memory deficits were found in patients with extensive periventricular damage.

Adult↗

PubMed1996

Influence of cognitive reserve on neuropsychological functioning in asymptomatic human immunodeficiency virus-1 infection.

OBJECTIVE: To evaluate the influence of cognitive reserve or brain reserve capacity on neuropsychological performance in early human immunodeficiency virus (HIV)-1 infection. DESIGN: Cross-sectional group comparison study, based on neuropsychological performance, of HIV-1 seropositive and HIV-1 seronegative participants. SUBJECTS: Seventy-five medically asymptomatic HIV-1-seropositive homosexual or bisexual men and 50 HIV-1-seronegative homosexual or bisexual male controls. Subjects were grouped by HIV-1 status (seropositive vs seronegative) and by cognitive reserve scores (low reserve vs high reserve). MEASURES: Cognitive reserve scores were based on a combination of years of education, a measure of occupational attainment, and an estimate of premorbid intelligence. Performance on a battery of neuropsychological tests was summarized by empirically derived factor scores and clinical summary ratings. RESULTS: The HIV-1-seropositive subjects with low cognitive reserve scores exhibited significantly greater deficits on measures of attention and information processing speed, verbal learning and memory, executive functioning, and visuospatial performance than did the HIV-1-seropositive subjects with high cognitive reserve scores. In contrast, there were no significant group differences on these measures between both groups of HIV-1-seronegative subjects. CONCLUSIONS: Early neuropsychological impairments in HIV-1 infection are most evident in individuals with lower cognitive reserve. As has been found in other neurologic disorders, such as Alzheimer's disease, individuals with greater cognitive reserve may be less sensitive to the initial clinical effects of the underlying neuropathologic process.

Adolescent↗

PubMed1995

Direct visual pathways for reaching movements in the macaque monkey.

The brain seems to process the location of objects faster than their intrinsic features, such as size, when these parameters are used to guide action. To uncover a potential anatomical substrate of these different processing speeds, we investigated in the monkey the pathways linking extrastriate visual cortex with the dorsal premotor area, a frontal area known to be involved in visually guided reaching movements. Retrogradely transported anatomical tracers were injected at physiologically defined sites and the distribution of labelled cells was examined in the ipsilateral cortex. We found a projection to the dorsal premotor cortex from the parieto-occipital area (PO). This area receives direct projections from the primary visual cortex (V1), and is part of the dorsal visual stream involved in the processing of spatial information. No direct projections to the dorsal premotor cortex arise from the ventral visual areas, thought to process object features. Our finding provides evidence for direct pathways from the dorsal visual stream to the dorsal premotor cortex and supports the view that the location of objects is processed faster by the brain than their intrinsic features.

Animals↗

PubMed1998

Neurobehavioral dimensions of olivopontocerebellar atrophy.

Twenty-one patients with olivopontocerebellar atrophy (OPCA) and 21 normal controls of equivalent age, gender, and educational levels underwent a series of neurobehavioral tests thought to measure frontal lobe and parietal lobe functions as well as information processing speed. The patients with OPCA had higher reaction times and movement times, confirming the results of previous experiments. They had lower scores for some tests thought to be sensitive to dysfunction of the frontal lobe, such as hand sequencing, verbal reasoning, and proverb interpretation. Deficits in copying a simple figure and in immediate visual-spatial memory, thought to be indicative of parietal lobe dysfunction, were also discerned. These results are consistent with the hypothesis that the cerebellum is involved in visual-spatial working memory that requires rapid information processing, and that it modulates parietal lobe- and frontal lobe-mediated functions.

Adult↗

PubMed2005

The relationship of structural alterations to cognitive deficits in schizophrenia: a voxel-based morphometry study.

BACKGROUND: Region of interest studies have identified a number of structure-cognition associations in schizophrenia and revealed alterations in structure-cognition relationship in this population. METHODS: We examined the relationship of structural brain alterations, identified using voxel-based morphometry, to cognitive deficits in 45 schizophrenia patients relative to 43 healthy control subjects and tested the hypothesis that structure-cognition relationship is altered in schizophrenia. RESULTS: Patients had smaller total brain, gray matter, and white matter volumes. Regional alterations were left-hemisphere specific, including: gray matter reduction of inferior frontal, lingual, and anterior superior temporal gyri; white matter reduction of posterior and occipital lobes; and gray matter increase of the putamen and the precuneus. Smaller whole brain and gray matter volumes were associated with lower premorbid intelligence quotient (IQ) and poorer performance on IQ-dependent cognitive measures in patients and to a similar extent in control subjects. Larger precuneus was associated with better immediate verbal memory in patients, whereas verbal and nonverbal memory were positively associated with inferior frontal gyrus volume in control subjects. Smaller occipital white matter volume was associated with slower information processing speed in patients but not in control subjects. CONCLUSIONS: Regional volume alterations are associated with specific cognitive deficits in schizophrenia. Some structure-cognition relationships differentiate this population from healthy control subjects.

Adolescent↗

PubMed2006

The structural brain correlates of cognitive deficits in adults with Klinefelter's syndrome.

CONTEXT: Adults with Klinefelter's syndrome (KS) are known to present disturbances of language skills and delayed learning abilities. OBJECTIVES: The aim of this study was to assess brain morphometry in KS and to correlate eventual volumetric changes with performance on neuropsychological tests. PATIENTS: Patients included 18 KS adults and 20 age-matched controls. METHODS: All participants underwent prospectively double-spin-echo brain magnetic resonance imaging and neuropsychological testing of verbal and nonverbal domains. On the axial stack of magnetic resonance imaging slices, regional brain volumes were measured either by automated segmentation (full brain, total cerebrospinal fluid, and ventricular volume) or manual drawing with help of a neuroanatomy atlas (frontal, temporal, and parietal lobes, gray matter component of the lobes, cerebellar hemispheres, and hippocampal complexes). RESULTS: KS patients performed significantly lower than controls on language-related tasks exploring verbal processing speed and verbal executive function. They were diagnosed with significant enlargement of ventricular volume and bilateral reduction of cerebellar hemispheres. Furthermore, after separation of participants according to handedness and after correction of regional brain volumes for atrophy, a significant reduction of left temporal lobe volume was found in KS compared with controls. Ventricular volume was inversely correlated with cognitive function, whereas left temporal lobe volume was positively correlated with language-related tasks. CONCLUSION: This study hypothesizes that supernumerary X-chromosome and/or congenital hypogonadism provoke structural alterations in the subcortical pathways involved in language processing, thus providing a neurobiological substrate for cognitive deficits in KS.

Adolescent↗

PubMed2001

Demographic, health, cognitive, and sensory variables as predictors of mortality in very old adults.

Cognitive and sensorimotor predictors of mortality were examined in the Australian Longitudinal Study of Ageing, controlling for demographic and health variables. A stratified random sample of 1,947 males and females aged 70 and older were interviewed, and 1,500 were assessed on measures of health, memory. verbal ability, processing speed, vision, hearing, and grip strength in 1992 and 1994. Analyses of incident rate ratios for mortality over 4- and 6-year periods were conducted using Cox hierarchical regression analyses. Results showed that poor performance on nearly all cognitive variables was associated with mortality, but many of these effects were explained by measures of self-rated health and disease. Significant decline in hearing and cognitive performance also predicted mortality as did incomplete data at Wave 1. Results suggest that poor cognitive performance and cognitive decline in very old adults reflect both biological aging and disease processes.

Aged↗

PubMed2006

The association between depressive mood and cognitive performance in an elderly general population - the MEMO Study.

The aim of this study was to analyse the influence of the severity of depressive symptoms on different domains of cognitive function in the elderly. In a population-based cross-sectional study, 385 participants aged 65-83 years were interviewed with the Center for Epidemiologic Studies Depression Scale (CES-D) and performed a standardized neuropsychological test assessing attention, memory, cognitive speed and motor function. Multivariate linear regression analyses revealed a significant effect of depressive symptoms on a single test (Stroop test 1) and two summary scores (memory and motor function). After full adjustment for education and Mini Mental State Examination, the memory score was partly attenuated. Stratified analysis showed that an increase in CES-D scores led to a larger decline of cognitive test results in participants with mild to moderate depressive symptoms, compared to those with a high degree of depressive symptoms. Our results suggest that depressive mood in older adults is primarily associated with decreased processing speed and motor functioning, but not executive control functions. According to our results depressive mood is not necessarily associated with memory deficits in older adults. Changes in depressive symptoms in milder forms of depressive mood are associated with a larger decline in cognitive function than in severer forms of depressive mood.

Affect↗

PubMed1997

Auditory information processing during acute insulin-induced hypoglycaemia in non-diabetic human subjects.

Acute insulin-induced hypoglycaemia impairs performance on tests of general mental ability in humans. It is recognized that different brain functions vary in their sensitivity to neuroglycopenia, but little is known about the effects of neuroglycopenia on specific brain processes. The effect of controlled hypoglycaemia on two aspects of auditory information processing (auditory temporal processing and simple auditory processing) was examined in a homogeneous group of 20 healthy non-diabetic human subjects. Auditory temporal processing (temporal order discrimination) and simple auditory processing (pitch discrimination, single-tone duration and single-tone loudness discrimination) tests were part of the Test of Basic Auditory Capabilities (TBAC). Two tests of general cognitive performance (Digit Symbol Substitution and Trail Making B) were included to provide a measure of general brain functioning during hypoglycaemia. Hypoglycaemia lead to a significant deterioration in auditory temporal processing (P < 0.01), and a deterioration in one of three tasks of simple auditory processing (discrimination of single-tone loudness, P < 0.05). Significant disruptions also occurred in both tests of general brain functioning. These results are congruent with other studies in human subjects, showing a disruptive effect of hypoglycaemia on visual information processing when examined under conditions of limited perceptual time, and they provide further evidence of the importance of sensory processing speed in basic perceptual and cognitive functions. The disruptive effect of moderate insulin-induced hypoglycaemia on auditory perception may have implications for insulin-treated diabetic humans exposed to this metabolic stress, because of the importance of hearing in everyday life.

Acoustic Stimulation↗

PubMed1999

Nonlinear Optics for High-Speed Digital Information Processing.

Recent advances in developing nonlinear optical techniques for processing serial digital information at high speed are reviewed. The field has been transformed by the advent of semiconductor nonlinear devices capable of operation at 100 gigabits per second and higher, well beyond the current speed limits of commercial electronics. These devices are expected to become important in future high-capacity communications networks by allowing digital regeneration and other processing functions to be performed on data signals "on the fly" in the optical domain.

Journal Article↗

PubMed2003

Long term effects of oral sustained release morphine on neuropsychological performance in patients with chronic non-cancer pain.

Morphine is increasingly used in patients with chronic non-cancer pain, but a major concern associated with chronic use relates to possible cognitive side-effects. The aim of this long-term prospective study was to evaluate the cognitive impact of oral sustained release morphine in patients with non-cancer pain. A battery of neuropsychological tests to explore attention, psychomotor speed and memory was administered. The effects of morphine on pain, quality of life, mood, subjective memory impairment and side-effects were also investigated. Evaluations were performed at baseline in patients free from opioids and then after 3, 6 and 12 months. Twenty-eight patients were included: 18 received oral sustained morphine (range 40-140 mg/day), ten patients stopped morphine prematurely because of side-effects or insufficient pain relief and were followed as a control group. There was no impairment of any neuropsychological variable over time in the morphine treated patients in comparison with the control group. Two measures of information processing speed - the Stroop interference score and the digit symbol test were improved at 6 and 12 months and there were significant correlations with the pain relief and improvement of mood. Self-reported memory impairment improved notably in responders to morphine. Morphine induced persisting effects on pain, and to a lesser extent on quality of life and mood. The visual analog scale score for side-effects increased at 12 months and essentially consisted of gastrointestinal disorders. This study demonstrates that 12 months treatment with oral morphine does not disrupt cognitive functioning in patients with chronic non-cancer pain and instead results in moderate improvement of some aspects of cognitive functioning, as a consequence of the pain relief and concomitant improvement of well-being and mood.

Administration, Oral↗

PubMed2005

Mapping the developmental constraints on working memory span performance.

This study investigated the constraints underlying developmental improvements in complex working memory span performance among 120 children of between 6 and 10 years of age. Independent measures of processing efficiency, storage capacity, rehearsal speed, and basic speed of processing were assessed to determine their contribution to age-related variance in complex span. Results showed that developmental improvements in complex span were driven by 2 age-related but separable factors: 1 associated with general speed of processing and 1 associated with storage ability. In addition, there was an age-related contribution shared between working memory, processing speed, and storage ability that was important for higher level cognition. These results pose a challenge for models of complex span performance that emphasize the importance of processing speed alone.

Age Factors↗

PubMed2006

Reading ability is negatively related to Stroop interference.

Stroop interference is often taken as evidence for reading automaticity even though young and poor readers, who presumably lack reading automaticity, present strong interference. Here the relationship between reading skills and Stroop interference was studied in a 7th-grade sample. Greater interference was observed in children diagnosed with reading disability (dyslexia) than in unimpaired children. Moreover, poorer reading skills were found to correlate with greater Stroop interference in the general school population. In correlation and regression analyses, interference was primarily associated with reading speed, with an additional unique contribution of reading accuracy. Color naming errors were few and not comparably related to reading skills. The relation of reading skill to Stroop interference was examined in computational modeling simulations. The production model of Roelofs [Roelofs, A. (2003). Goal-referenced selection of verbal action: modeling attentional control in the Stroop task. Psychological Review, 110, 88-125], in which interference is primarily due to word stimuli having direct access to word form encoding whereas color naming must pass through concept activation and lemma selection, was found to account well for the human data after imposing covariation constraints on parameters controlling word processing and blocking latency, in modifications not affecting the model's previous fit to other data. The connectionist model of Cohen, Dunbar, and McClelland [Cohen, J. D., Dunbar, K., & McClelland, J. L. (1990). On the control of automatic processes: a parallel distributed processing account of the Stroop effect. Psychological Review, 97, 332-361], in which interference is caused by differential route strength, implementing an automaticity account, approximated the observed patterns with network-wide parameter manipulations not specific to reading, such as processing speed and response threshold, likely to affect previously optimized performance. On the basis of the empirical and modeling data we argue for a direct link between reading skill and interference, beyond the effects of executive functioning.

Adolescent↗

PubMed1993

Age and physical activity effects on reaction time and digit symbol substitution performance in cognitively active adults.

University professors (N = 56), divided into two age groups (< 50 years and > 50 years) and two physical activity level groups (high and low), were tested on three tasks requiring increasingly complex cognitive processing--simple reaction time (SRT), choice reaction time (CRT), and on a digit symbol substitution test (DSST). A significant main effect for exercise, with high active subjects performing better than low active subjects, was found for SRT (p < .001) and CRT (p < .01) but not for DSST (p < .09). Significant main effects for age, with younger subjects performing better than older subjects, were found on DSST (p < .01) and CRT (p < .05) but not for SRT (p < .09). The observation that the effect of age was more pronounced with increasing task complexity is consistent with previous research. However, the tendency for exercise effects to decrease with increasing task complexity is not consistent with former findings, suggesting that perhaps the controlled high level of cognitive activity of subjects in this study may have offset the usual effects of exercise on information processing speed. No significant Age x Activity Level interactions were found on any of the dependent raw score data. However, compared to normative scores of the population at large, there was a slight increase in DSST percentile ranks with age for the older aerobically active professors, whereas a decrease occurred for the inactive subjects.

Adult↗

PubMed1989

Categorization of disoriented faces in the cerebral hemispheres of normal and commissurotomized subjects.

We examined the capacity of the cerebral hemispheres to process faces that deviate from canonical perspective. In Experiment 1, normal Ss performed a gender categorization of faces presented at varying angular orientations in the left visual field (LVF) or right visual field (RVF). Orientation affected processing speed, more so in the RVF than in the LVF. The function relating reaction times to disorientation of the faces was approximately monotonic and reflected the increased difficulty in extracting relevant configurational information as the faces were rotated from canonical perspective. In Experiment 2, 3 commissurotomized Ss performed the same task. They responded above chance in the 2 visual fields, and the pattern of their results was similar to that obtained with the normal Ss, but the effect of disorientation was considerably more pronounced. It is suggested that the right hemisphere contribution becomes more critical the further the visual pattern departs from conventional view. Issues regarding the specification of processes correcting for disorientation and comparison of normal and commissurotomized Ss are discussed.

Adult↗

PubMed1993

Application of Hick's law of response speed in Alzheimer and Parkinson diseases.

Reaction time in normal subjects is known to increase in a log-linear fashion relative to the number of alternative choices. However, this relationship (formalized as "Hick's law") has received limited investigation in populations with neurological cognitive impairment. The present study used timed sorting of standard playing cards to test Hick's law for 20 young control subjects, and 20 each of age-matched elderly subjects with Alzheimer disease, Parkinson disease, and no cognitive abnormalities. Although Parkinson patients were slowest in the simple tasks of dealing out the cards and sorting by color, Alzheimer patients showed the greatest slowing for the more cognitively complex conditions of sorting by suit and rank of the cards. The performance of all four groups followed Hick's law in displaying a significant linear relationship between response time and log2 of the number of choices. These findings suggest that, although limitations of information-processing speed in Alzheimer and Parkinson disease affected choice response time, there may be sparing of fundamental cognitive organization in these disorders.

Adult↗

PubMed1998

Cognitive processing efficiency in schizophrenia: generalized vs domain specific deficits.

The issue of generalized vs specific cognitive deficits in schizophrenia was explored by examining reaction time data from 40 published studies with 196 reaction time conditions. Using a regression-based approach, the proportional relationship between the response times of groups with schizophrenia was compared with those of age-matched, healthy comparison groups. Through this method, the extent to which deficits in processing efficiency are explained by a single factor, general processing speed, was compared with possible domain specific or task specific deficits. The results suggest that, overall, the data conforms well to a general linear slowing model which accounts for 87% of the variance in reaction time performance. Some additional variance, however, is accounted for by different degrees of linear slowing for three types of tasks: tasks involving selective attention/inhibition showed the most slowing (2.3-times slower for schizophrenia), followed by lexical tasks (1.8-times slower for schizophrenia), and finally, non-lexical tasks showed the least slowing (1.4-times slower for schizophrenia). This pattern is distinct from other groups showing generalized slowing, such as older adults, and suggests a unique pattern of information processing deficits in schizophrenia.

Adult↗

PubMed2000

[The characteristics of autonomic regulation in persons with different levels of mental work capacity].

The aim of the study was investigation of efficiency of mental activity in people with different types of vegetative regulation. The 32 operators Chernobyl atomic station aged 26-54 were examined. The mental activity was studied by two computer's tests. The registration and analysis cardio-intervals were processing in set time interval. The results of investigation are showed that efficiency of operator's activity related with quality, productivity and information processing speed. In successful operators are showed transition from determination to stochastic types of heart rhythm regulation. In non-successful operators are showed transition from stochastic to determination types of heart rhythm regulation. Thus the increase of determinate organization of heart rhythm system regulation related with changes of mental activity algorithm and with intensification of psychophysiological functions tension.

Adult↗