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PubMed2004

The development of complex sentence interpretation in typically developing children compared with children with specific language impairments or early unilateral focal lesions.

This study compared sentence comprehension skills in typically developing children 5-17 years of age, children with language impairment (LI) and children with focal brain injuries (FL) acquired in the pre/perinatal period. Participants were asked to process sentences 'on-line', choosing the agent in sentences that varied in syntactic complexity (actives, passives, subject clefts and object clefts), and in the presence or absence of a subject-verb agreement contrast. Results revealed that accuracy and processing speeds vary with syntactic complexity in all groups, reflecting the frequency and regularity of sentence types. Developmental changes continued throughout childhood, as children became faster and more accurate at processing more complex sentence structures. Children with LI and children with FL were quite profoundly delayed, displaying profiles similar to, or more impaired than those of younger children, but there was no evidence in the FL group for a disadvantage in left- vs. right-hemisphere-damaged children. Children with LI showed one unique pattern: higher than normal costs (reflected in reaction times) in using converging information from subject-verb agreement, in line with studies suggesting special vulnerabilities in grammatical morphology in this group. Results are discussed in terms of the Competition Model, a theory of language processing designed to account for the statistical changes in performance that are observed during development, and the probabilistic deficits in children with language impairments.

Adolescent↗

PubMed2000

Exploring the relationship between age, executive abilities, and psychomotor speed.

Age-related declines in executive abilities have been widely reported and are thought to result from neuropathological changes in the prefrontal cortex. Some investigators have suggested that age-related changes in cognition may be the result of slowed information processing speed rather than declines in specific cognitive abilities. We examined the relationships among age, executive abilities, and psychomotor speed in 40 older adults and 46 young adults. Both verbal and nonverbal tasks were administered that measured 2 aspects of executive ability: set formation and set shifting. Executive and psychomotor speed tasks were paired based on similarities in basic task demands. Our results revealed that poorer executive performance was associated with increasing age. Further, although psychomotor speed attenuated the relationship, age accounted for a unique and significant proportion of variance in executive performance after controlling for psychomotor speed. These results suggest that age has an effect on prefrontally mediated executive abilities that cannot be explained solely in terms of psychomotor slowing.

Adolescent↗

PubMed2006

Losses in gross brain volume and cerebral blood flow account for age-related differences in speed but not in fluid intelligence.

Age-related gross head size; adjusted age-related change in brain volume and carotid and basilar blood flow; as well as scores on 3 tests of fluid intelligence (gf), 2 tests of information-processing speed, 2 memory tests, and 3 tests of executive function were obtained from 69 volunteers aged from 62 to 84 years. Brain volume negatively predicted scores on all 10 cognitive tasks, accounting for up to 78% of age-related variance in scores on the speed tasks and on 1 executive task. Cerebral blood flow (CBF) negatively predicted scores on 8 cognitive tasks, accounting for up to 36% of age-related variance in speed scores. However, neither brain volume nor CBF accounted for significant age-related variance between individuals on any of 3 gf tests. We conclude that speed, but not gf, is an exceptionally sensitive behavioral index of the progress of gross brain changes that affect cognition in old age and that speed and gf do not reflect integrity of the same functional systems.

Aged↗

PubMed1989

Backward masking, information processing, and schizophrenia.

Many researchers have used backward masking to examine information-processing speed in schizophrenic subjects. The validity of this approach rests upon two main assumptions. One is that the mask effectively limits the time a previously presented stimulus is available for processing. The other is that the components of the masking mechanism in schizophrenic subjects are comparable to those in control groups. It is argued that the masking procedures used in these studies fail to meet either assumption. Alternative interpretations of these investigations, however, suggest important hypotheses for further research in our quest to understand information-processing deficits associated with schizophrenia.

Humans↗

PubMed2004

A grid computing infrastructure for MEG data analysis.

Magnetoencephalography (MEG) is widely used for studying brain functions, but clinical applications of MEG have been less prevalent. One reason is that only clinicians who have highly specialized knowledge can use MEG diagnostically, and such clinicians are found at only a few major hospitals. Another reason is that MEG data analysis is getting more and more complicated, and deals with a large amount of data, and thus requires high-performance computing. These problems can be solved by the collaboration of human and computing resources distributed in multiple facilities. A new computing infrastructure for brain scientists and clinicians in distant locations was therefore developed by the Grid technology, which provides virtual computing environments composed of geographically distributed computers and experimental devices. A prototype system connecting an MEG system at the AIST in Japan, a Grid environment composed of PC clusters at Osaka University in Japan and Nanyang Technological University in Singapore, and user terminals in Baltimore was developed. MEG data measured at the AIST were transferred in real-time through a 1-GB/s network to the PC clusters for processing by a wavelet cross-correlation method, and then monitored in Baltimore. The current system is the basic model for remote-access to MEG equipment and high-speed processing of MEG data.

Computing Methodologies↗

PubMed2004

Evidence for synergistic modulation of early information processing by nicotinic and muscarinic receptors in humans.

Impairments in early information processing are a hallmark feature of diverse neuropsychiatric disorders including schizophrenia and Alzheimer's disease (AD). Several lines of evidence implicate a dysfunction of the cholinergic system in these disorders, particularly in AD where there is known degeneration in major cholinergic pathways. Inspection time (IT), a measure of early visual information processing speed, has been shown to be sensitive to cholinergic manipulation. The current study employed the IT task to (1) examine the independent roles of nicotinic and muscarinic receptors in modulating information processing and (2) investigate the interaction of nicotinic and muscarinic receptor systems in modulating information processing. Twelve healthy participants completed a randomized, double-blind, placebo-controlled study under four drug conditions; (1) placebo, (2) mecamylamine (15 mg; oral), (3) scopolamine (0.4 mg, s.c.), (4) mecamylamine (15 mg) + scopolamine (0.4 mg). IT measures were examined at baseline and 2.5 h post drug administration. Selective blockade of nicotinic receptors with mecamylamine did not significantly impair IT, whereas selective blockade of muscarinic receptors with scopolamine produced a significant but small impairment in IT. Combined blockade of both receptor types with scopolamine and mecamylamine produced a large impairment in IT performance. The results indicate that both nicotinic and muscarinic receptors are involved in modulating IT, and that the two systems may function synergistically to modulate early visual information processing. These findings suggest that functional abnormalities in both nicotinic and muscarinic systems may underlie deficits in early visual information processing seen in disorders such as Alzheimer's disease and schizophrenia.

Adult↗

PubMed2002

Infant discrimination of rapid auditory cues predicts later language impairment.

The etiology and mechanisms of specific language impairment (SLI) in children are unknown. Differences in basic auditory processing abilities have been suggested to underlie their language deficits. Studies suggest that the neuropathology, such as atypical patterns of cerebral lateralization and cortical cellular anomalies, implicated in such impairments likely occur early in life. Such anomalies may play a part in the rapid processing deficits seen in this disorder. However, prospective, longitudinal studies in infant populations that are critical to examining these hypotheses have not been done. In the study described, performance on brief, rapidly-presented, successive auditory processing and perceptual-cognitive tasks were assessed in two groups of infants: normal control infants with no family history of language disorders and infants from families with a positive family history for language impairment. Initial assessments were obtained when infants were 6-9 months of age (M=7.5 months) and the sample was then followed through age 36 months. At the first visit, infants' processing of rapid auditory cues as well as global processing speed and memory were assessed. Significant differences in mean thresholds were seen in infants born into families with a history of SLI as compared with controls. Examination of relations between infant processing abilities and emerging language through 24 months-of-age revealed that threshold for rapid auditory processing at 7.5 months was the single best predictor of language outcome. At age 3, rapid auditory processing threshold and being male, together predicted 39-41% of the variance in language outcome. Thus, early deficits in rapid auditory processing abilities both precede and predict subsequent language delays. These findings support an essential role for basic nonlinguistic, central auditory processes, particularly rapid spectrotemporal processing, in early language development. Further, these findings provide a temporal diagnostic window during which future language impairments may be addressed.

Apgar Score↗

PubMed1992

Spatial code interference on directional responses.

The interference from an irrelevant position cue was compared in a reaction-time paradigm using voice and manual responses. The subjects were required to say 'left' or 'right' or to press left or right keys in response to arrow directions, and the arrows were presented at left or right side display positions irrelevant to the task. Display position significantly increased latency when it did not match the response to the relevant direction cue for both spatial (key-press) and non-spatial (voice) responses (73 and 59 ms, respectively). When presented alone, the position cue was processed faster than the direction cue for both manual and verbal responses. Results are discussed in terms of a common abstract mediator for left-right responses between modes and the processing speed difference between the relevant and irrelevant cue. The irrelevant left-right position code may occupy some limited-capacity channel ahead of the left-right code derived from processing the relevant direction cue.

Humans↗

PubMed2003

Grammatical and resource components of sentence processing in Parkinson's disease: an fMRI study.

BACKGROUND: Sentence comprehension requires linguistic processing as well as cognitive resources such as working memory (WM) and information-processing speed (IPS). The authors hypothesize that sentence comprehension difficulty in patients with mild PD is due to degradation of the large-scale neural network that supports cognitive resources during sentence processing. OBJECTIVE: To understand the neural basis for sentence comprehension difficulty in PD. METHOD: Regional brain activity with blood oxygenation level-dependent fMRI was monitored while seven PD patients and nine healthy seniors answered a simple probe about written sentences that vary in their grammatical and cognitive resource properties. RESULTS: Healthy seniors recruited posterolateral temporal and ventral inferior frontal regions of the left hemisphere, brain regions associated with grammatical processing that were also activated by PD patients. Healthy seniors also recruited left dorsal inferior frontal, right posterolateral temporal, and striatal regions that are associated with cognitive resources during sentence processing. Direct contrasts showed that striatal, anteromedial prefrontal, and right temporal regions are recruited to a significantly lesser degree in PD, but these patients have increased activation of right inferior frontal and left posterolateral temporal-parietal areas during sentence comprehension. CONCLUSION: These findings associate impaired sentence comprehension in PD with interruption of a large-scale network important for cognitive resources during sentence processing. These results also imply compensatory up-regulation of cortical activity that allows patients with mild PD to maintain sentence comprehension accuracy.

Aged↗

PubMed2004

Alteration of raw-milk cheese by Pseudomonas spp.: monitoring the sources of contamination using fluorescence spectroscopy and metabolic profiling.

Thirty Pseudomonas spp. strains isolated from milk, water, cheese centre and cheese surface in two traditional workshops manufacturing raw milk St. Nectaire cheese were characterised by fluorescence spectroscopy and Biolog metabolic profiling. Factorial discriminant analysis (FDA) of the two data sets revealed clear linkages between groups of isolates. In the first workshop, milk could be incriminated as the sole source of cheese contamination. In the second one, milk and cheese centre isolates were found similar but surface cheese contaminants could be linked to a secondary contamination originating from water. Thus, it is possible to characterise, differentiate and trace Pseudomonas spp. strains using the fluorescence and metabolic profiling techniques. In addition, the two data sets were found highly correlated by canonical correlation analysis (CCA). Fluorescence spectroscopy however showed several advantages because of its low cost and processing speed.

Animals↗

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↗

PubMed2005

Preattentive orienting in adolescents with mental retardation.

Visual attention is preattentively drawn to abrupt onsets of stimuli appearing in a visual array. In this experiment, I examined the speed of attentional capture for persons with and without mental retardation. Participants identified target stimuli that were signaled by a valid location cue (20% of the time), an invalid location cue (60% of the time), or no cue (20% of the time). Participants without mental retardation exhibited maximum influence of the cue at cue/target separations that were 100 msec shorter than did participants with mental retardation. These results indicate that processing-speed differences between persons with and those without mental retardation can be observed even when processing resources not involved in the information processing.

Adolescent↗

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↗

PubMed2006

Children's naming and word-finding difficulties: descriptions and explanations.

PURPOSE: There is a substantial minority of children for whom lexical retrieval problems impede the normal pattern of language development and use. These problems include accurately producing the correct word even when the word's meaning is understood. Such problems are often referred to as word-finding difficulties (WFDs). This article examines the nature of naming and lexical retrieval difficulties in these and other groups of children. METHOD: A review of the relevant literature on lexical access difficulties in children with word-finding difficulties was conducted. Studies were examined in the terms of population parameters and comparison groups included in the study. RESULTS AND CONCLUSIONS: Most discussions of the cognitive processes causing lexical retrieval difficulties refer to semantics, phonology, and processing speed. The authors propose that understanding of these topics will be further advanced by the use of appropriate methodology to test developmental models. In this way it will be possible to identify the processes that contribute to successful lexical retrieval and the processes that result in retrieval difficulties.

Child↗

PubMed2005

Visual information processing in the lion-tailed macaque (Macaca silenus): mental rotation or rotational invariance?

Mental rotation is a widely accepted concept indicating an image-like mental representation of visual information and an analogue mode of information processing in certain visuospatial tasks. In the task of discriminating between image and mirror-image of rotated figures, human reaction times increase with the angular disparity between the figures. In animals, tests of this kind yield inconsistent results. Pigeons were found to use a time-independent rotational invariance, possibly indicating a non-analogue information processing system that evolved in response to the horizontal plane of reference birds perceive during flight. Despite similar ecological demands concerning the visual reference plane, a sea lion was found to use mental rotation in similar tasks, but its processing speed while rotating three-dimensional stimuli seemed to depend on the axis of rotation in a different way than found for humans in similar tasks. If ecological demands influence the way information processing systems evolve, hominids might have secondarily lost the ability of rotational invariance while retreating from arboreal living and evolving an upright gait in which the vertical reference plane is more important. We therefore conducted mental rotation experiments with an arboreal living primate species, the lion-tailed macaque. Performing a two-alternative matching-to-sample procedure, the animal had to decide between rotated figures representing image and mirror-image of a previously shown upright sample. Although non-rotated stimuli were recognized faster than rotated ones, the animal's mean reaction times did not clearly increase with the angle of rotation. These results are inconsistent with the mental rotation concept but also cannot be explained assuming a mere rotational invariance. Our study thus seems to support the idea of information processing systems evolving gradually in response to specific ecological demands.

Animals↗

PubMed2001

Memory performance used to detect radiation effects on cognitive functioning.

Although radiotherapy remains a necessary and frequently used treatmentfor brain tumors, uncertainty remains about the nature and severity of neurocognitive morbidity. We show that verbal-semantic memory (free recall of word list) is sensitive to damaging radiation effects in 20 patients with low-grade, supratentorial, primary brain tumors who received moderate doses of partial-brain irradiation. We previously reported that verbal-semantic memory is dissociated from visual memory (acquisition and recall) during the same phase ofradiation effects, indicating that memory is differentially affected by radiation. In this study, we provide evidence of the nature of the iatrogenic radiation effect on memory by testing collateral cognitive functions that might explain the specific memory impairment. We found that the verbal-semantic recall impairment was not associated with impairments in auditory attention, auditory processing speed, auditory-verbal working memory, or in the temporal coding or subjective organization of word-list recall. These findings focus damaging radiation effects on primary retrievalprocesses, rather than on earlier cognitive processes or executive processes affecting recall. Knowledge of the specific patterns of change in cognition would guide the differential diagnosis and rehabilitation of survivors of brain tumors whose conditions are complicated by tumors with multiple treatments.

Adult↗

PubMed2005

Improved fingerprint identification with supervised filtering enhancement.

An important step in the fingerprint identification system is the reliable extraction of distinct features from fingerprint images. Identification performance is directly related to the enhancement of fingerprint images during or after the enrollment phase. Among the various enhancement algorithms, artificial-intelligence-based feature-extraction techniques are attractive owing to their adaptive learning properties. We present a new supervised filtering technique that is based on a dynamic neural-network approach to develop a robust fingerprint enhancement algorithm. For pattern matching, a joint transform correlation (JTC) algorithm has been incorporated that offers high processing speed for real-time applications. Because the fringe-adjusted JTC algorithm has been found to yield a significantly better correlation output compared with alternate JTCs, we used this algorithm for the identification process. Test results are presented to verify the effectiveness of the proposed algorithm.

Algorithms↗