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Results for “Task Shifting”

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PubMed2006

Attention lights up new object representations before the old ones fade away.

We investigated how attention shifts from one object to another by recording neuronal activity in the primary visual cortex. Monkeys performed a contour-grouping task in which they had to select a target curve and ignore a distractor curve. Some trials required a shift of attention, because the target and distractor curves were switched during the course of the trial. We monitored the dynamics of this attention shift in area V1, in which neuronal responses evoked by the target curve are stronger than those evoked by the distractor. The reallocation of attention was associated with a rapid and strong enhancement of responses to the newly attended curve, followed, after approximately 60 ms, by a weaker suppression of responses to the curve from which attention was removed. We conclude that attention can be rapidly allocated to a new object before it disengages from the previously attended one.

Animals↗

PubMed2001

Work environment of Danish shift and day workers.

OBJECTIVES: Both shift work and other work environment factors have been shown to be related to heart disease. This study examined whether shift work is associated with other work environment factors related to heart disease in a random sample of the population. If so, shift work could be acting as a proxy for work environment differences. METHODS: Data on 5940 employees in the Danish Work Environment Cohort Study from 1990 were reanalyzed. The information included work schedules [permanent day work, irregular workhours (including morning work), 2-shift or fixed evening and 3-shift or fixed night], length of workweek, physical factors (noise, heat, dust, passive smoking, walking, standing and monotonous repetitive tasks), and psychosocial factors (including demands and control dimensions, social support, conflicts and job insecurity). RESULTS: At least 1 group of shift workers had a higher prevalence of nearly every unfavorable work environment factor investigated. Exceptions were dust exposure and quantitative demands. Especially conflicts at work and low decision latitude were higher among all the groups of shift workers, and all-day walking or standing work and part-time jobs were more often found among female shift workers. The 3 different shiftwork groups were exposed to different parts of the work environment, and also men and women in shift work differed in relation to the work environment. Age and social class influenced the relationship, but not in any particular pattern. CONCLUSIONS: In a heterogenous population shift work was found to be associated with other work environment factors suspected to cause heart disease.

Adolescent↗

PubMed1998

The Taps Project 40: quality of care provisions for the elderly mentally ill--traditional vs alternative facilities.

The study evaluates some aspects of care reprovision for psychogeriatric patients. Seven hospital wards are compared with four community settings, established as part of the reprovision programme for Friern Hospital in London. Each facility was assessed for policy and programme, social climate and physical characteristics; staff attitudes in regard to their tasks, training needs and job satisfaction were also explored. Community settings were superior to hospital wards in providing more privacy for the residents and were better equipped with physical amenities and safety features. There were relatively small differences between the way staff perceived the social climate in community homes and in hospital. The former were regarded as encouraging greater independence. Care staff in the hospital were more likely to express dissatisfaction with pay, working conditions and social status, while community staff were more dissatisfied with the quality of cooperation between staff members. Clients transferred to Social Services facilities had a higher level of functioning and needed less on-site medical care. This was further reflected by the lower frequency of nursing care tasks being performed by staff in community facilities. Overall, the shift towards a less medical model of care in community-based homes appears to be beneficial to psychogeriatric patients, provided that current and prospective physical needs of the residents are adequately addressed.

Attitude of Health Personnel↗

PubMed1997

Menstrual cycle phase and mood effects on perceptual asymmetry.

Several studies have reported shifts in perceptual asymmetry during the menstrual cycle, but the potential confounding effect of mood changes has been largely ignored. In this study, 24 female subjects completed four visual laterality tasks and a mood questionnaire at three phases of the cycle. Results indicate no overall effect of cycle phase on any of the asymmetry or mood scores. However, results revealed significant associations between affect and perceptual asymmetry on a face perception task. Implications for mood effects on perceptual asymmetry and future research on cycle-related shifts in asymmetry are discussed.

Adolescent↗

PubMed2002

Effects of pallidal deep brain stimulation and levodopa treatment on reaction-time performance in Parkinson's disease.

Basal ganglia-thalamocortical circuits play an important role in movement preparation and execution. Tracer, single-cell, and lesion studies in monkeys suggest the existence of topologically segregated motor and nonmotor basal ganglia cortical circuits. In this study we used deep brain stimulation (DBS) of the posteroventrolateral globus pallidus internus (GPi) in patients with Parkinson's disease to elucidate the function of the GPi in human sensorimotor behavior. This question was investigated by comparing the influence of DBS on patients' performance in various reaction-time tasks that differed with respect to cognitive but not motor requirements. As a main result, DBS improved performance on the different tasks independently of the complexity of the involved cognitive processing functions. Furthermore, the observed effects did not depend on the modality of the processed information. These results suggest that the functional state of the posteroventrolateral GPi selectively affects the motor stage in simple sensorimotor acts, because this stage was the only stage involved in all investigated tasks. In addition to DBS, we manipulated the levodopa medication state of the PD patients. In contrast to DBS, levodopa effects on reaction times were less consistent. Levodopa improved reaction times in choice reaction tasks significantly, while affecting reaction times in a simple reaction task to a lesser extent. Error analysis revealed that the medication-dependent reaction-time improvement in the choice reaction tasks was accompanied by an increase in errors, suggesting a shift of the speed-accuracy criteria of the patients. A similar pattern of results was not observed for the DBS effects. Taken together, our data are in agreement with recent findings in monkeys that indicate a topological organization of the GPi in which motor functions are localized in posterolateral regions apart from cognitive regions. Furthermore, our data show a way to uncover the subcortical-cortical circuitry serving human sensorimotor behavior.

Acoustic Stimulation↗

PubMed1982

Shift in cognitive asymmetries between wakings from REM and NREM sleep.

Twelve subjects were awakened from REM and NREM sleep and tested on three tests designed to measure functions attributed to the left cerebral hemisphere and three tests designed to measure right hemisphere function. A significant shift in cognitive profile was found in the direction of tasks attributed to left hemisphere performance following waking from NREM sleep relative to waking from REM sleep. These results are consistent with the observed reciprocal oscillations between left and right functions during the waking period and imply that performance of these specialized functions may be controlled by some of the same mechanisms that govern biorhythms.

Adult↗

PubMed1988

The relationship between alcohol intoxication and power in real-life non-alcoholic couples.

Thirty real life couples were randomly assigned to one of three groups, a control group, a men drink group (only men drinking alcohol), or a women drink group (only women drinking alcohol). The purpose was to test whether alcohol intoxication leads to shifts in power among men and women using an estimation task together with a measure of power fantasies. Men were more powerful in terms of outcome both in the control group and the women drink group, but women became more powerful when men drink. Responsibility aspects of the process follow this pattern and the process becomes more complex when women drink. Men over-estimate their influence especially as far as process is concerned. Power fantasies decrease for both men and women only when women drink. It is suggested that sex role stereotyping can explain the findings.

Adult↗

PubMed2004

Effects of neonatal excitotoxic lesions of the entorhinal cortex on cognitive functions in the adult rat.

The entorhinal cortex (EC) is involved in a variety of cognitive functions by virtue of its neuronal input from the neocortex and projection to the hippocampal formation and the limbic-striatal system. Neonatal lesions are increasingly considered useful models for disconnection syndromes such as schizophrenia. Therefore, we investigated the effects of neonatal EC lesions on adult rat behavior. Neonatal (postnatal day 7) lesions were inflicted by bilateral injections of ibotenate into the EC. Sham-lesioned (vehicle injection) and naive (unoperated) rats served as controls. Locomotor activity was measured in prepubertal and young adult rats. Adult rats were then tested for spatial learning in an eight-arm radial maze (reinforced delayed alternation) and for motivation (progressive ratio schedule of operant behavior). Finally, prepulse inhibition (PPI) of the acoustic startle reflex and locomotor activity were investigated with and without apomorphine (APO) challenge. Brain tissue damage was assessed using Nissl-staining. The total volume of the adult rat EC was reduced after neonatal ibotenate-injection. Neonatal EC-lesions increased perseveration only in a delayed task in the radial maze and induced a leftward-shift of breakpoints in operant responding. Lesions did not alter baseline locomotor activity, but enhanced the locomotor stimulating effect of APO. PPI was not affected by neonatal lesions of the EC with and without APO challenge. Neonatal lesions of the EC impaired the ability to hold information during delays and reduced motivation during operant behavior which reflects a state of anhedonia. Thus, they may serve as an animal model for certain aspects of schizophrenia.

Aging↗

PubMed1999

Temporal cortex activation during speech recognition: an optical topography study.

Cortical activity during speech recognition was examined using optical topography (OT), a recently developed non-invasive technique. To assess relative changes in hemoglobin oxygenation, local changes in near-infrared light absorption were measured simultaneously from 44 points in both hemispheres. A dichotic listening paradigm was used in this experiment, in which target stimuli and non-target stimuli were presented to different ears. Subjects were asked to track targets and to press a button when targets shifted from one ear to the other. We compared three tasks: (i) a control task, in which a tone was used as the target; (ii) a repeat task, in which the target was one repeated sentence; (iii) a story task, in which the targets were continuous sentences of a story. The activity for the story task, compared with the repeat task, was localized in the left superior temporal cortex. Relative to the control task, we observed in this region a larger increase in oxyhemoglobin concentration and a decrease in deoxyhemoglobin concentration in the story task than those in the repeat task. These results suggest that the activity in the left temporal association area reflects the load of auditory, memory, and language information processing.

Adult↗

PubMed2001

Prism adaptation to rightward optical deviation improves postural imbalance in left-hemiparetic patients.

Left-hemiparetic patients show predominant postural imbalance as compared to right-hemiparetic patients. The right hemisphere is crucial for generating internal maps used for perceptual and premotor processing of spatial information. Predominant postural imbalance with right-brain damage could thus result from a distortion of an internal postural map. Well-known manifestations of distorted internal maps due to right-hemisphere lesions, such as hemineglect, may show improvement following prism adaptation shifting the visual field to the right. We therefore investigated the effect of prism adaptation on postural imbalance in left-hemiparetic patients. Three groups of five patients were either adapted to prisms deviating the visual field to the right or left or exposed to neutral prisms while performing reaching movements of the right arm. Postural imbalance was reduced only following prism adaptation to the right. Thus, brief adaptation (i.e., 3 min) to rightward-shifting prisms can dramatically improve postural imbalance. This result shows that the effect of exposure to prisms that horizontally shift the visual field to the right in a reaching task generalizes to the postural system, and it suggests an interaction between horizontal and vertical reference frames. This also supports the theory that predominant postural imbalance in patients with right-brain damage may be partly related to a distortion of an internal postural map.

Adult↗

PubMed2002

Effects of contraction history on control and stability in explosive actions.

In this model study, the effect of contraction history in skeletal muscle on joint movement and stability was investigated. A joint system was constructed with two identical (antagonistic) muscles. The muscles were modelled either according to the Hill tradition or as a modified Hill system including history-dependent properties. The joint system underwent movements with full activity of both muscles, mimicking explosive actions with high stability demands. Movements starting away from a balanced mid-position, as well as perturbation experiments, were simulated. The comparison between the Hill and modified Hill systems showed that contraction history improved stability (stiffness under perturbation) and, under certain conditions, caused a shift in the final joint position, which depended on the task characteristics (starting position and perturbations characteristics). This result indicates that modulations of muscle activity, required to move a joint to a particular end-position, do not only depend on the end-position but also on the preceding movements. This finding does not agree with the equilibrium-point hypothesis and is discussed accordingly.

Biomechanical Phenomena↗

PubMed1991

A continuous-flow model for phonatory reaction time.

The purpose of this study was to validate a proposed continuous-flow model of phonatory reaction time by investigating the temporal order of selected laryngeal and neurophysiological events involved in a phonatory reaction time task. Ten normal speakers participated in a phonatory reaction time task. Laryngeal positioning movements prior to vocal fold closure (laryngeal shift) and onset of vocal fold vibration (acoustic onset) were recorded with an electroglottograph. P300 brain potentials were collected simultaneously, and they served as an index of a central process underlying reaction time. The obtained temporal ordering of laryngeal shift, P300, and acoustic onset supported a continuous-flow model of phonatory reaction time. Use of this model might yield information that is more accurate in explaining physiological function and more precise in describing temporal patterning than the serial model.

Adult↗

PubMedDate not supplied

The International Disability Rights Movement and the ICF.

PURPOSE: To outline the thinking of disabled people about their situation and status before the formulation of the ICIDH (International Classification of Impairment, Disability and Handicap) in 1980, the growth of the international disability rights movement since 1980, its subsequent involvement in the revision process and then its hopes as to the effectiveness of the ICF (the International Classification of Functioning, Disability and Health-the revised ICIDH) in the future. METHOD: This is a personal analysis based on the author's experience as a disability rights activist and as a member of the World Council of Disabled Peoples' International (DPI), elected in 1987 to represent DPI in the revision process and who later became Chair of the Environmental Task Force. RESULTS: These are shown to be a major shift from the medical model of disability to the adoption of the interactive model and the impacts of environmental factors in all aspects of health and functioning. CONCLUSIONS: That proper use of the environmental factors within the ICF will ensure appropriate policies, systems and services for health care and support, provide measurable indicators for health status and sustainable development and underpin the recognition that disability is a human rights issue.

Activities of Daily Living↗

PubMed2004

Neurovascular coupling analyzed non-invasively in the human brain.

Most functional brain imaging methods detect neuronal activations indirectly through the accompanying neurovascular response. Here, we demonstrate that a novel methodological approach, the combination of DC-magnetoencephalography (DC-MEG) and near-infrared spectroscopy (NIRS), allows non-invasive assessment of the dynamics of neurovascular coupling in the human brain: detecting directly slow neuronal processes (with time constants of 30s), DC-MEG revealed, even in unaveraged recordings, sustained neuronal activations at pericentral hand cortices contralateral to repetitive finger movements; these were accompanied by the ensuing local vascular response showing similar dynamical features as quantified by simultaneously recorded NIRS. This non-invasive approach opens a new avenue for the understanding of neurovascular coupling during physiological tasks as well as in diseases involving slow neuronal depolarization shifts and alterations of blood flow, such as stroke or migraine.

Adult↗

PubMed2006

A shift from diffuse to focal cortical activity with development.

Recent imaging studies have suggested that developmental changes may parallel aspects of adult learning in cortical activation becoming less diffuse and more focal over time. However, while adult learning studies examine changes within subjects, developmental findings have been based on cross-sectional samples and even comparisons across studies. Here, we used functional MRI in children to test directly for shifts in cortical activity during performance of a cognitive control task, in a combined longitudinal and cross-sectional study. Our longitudinal findings, relative to our cross-sectional ones, show attenuated activation in dorsolateral prefrontal cortical areas, paralleled by increased focal activation in ventral prefrontal regions related to task performance.

Age Factors↗

PubMed1993

Accommodative adaptation and age of onset of myopia.

Tonic accommodation in an empty field and accommodative adaptation, defined as accommodation shift after 2 min viewing of a 4 D near task, were measured using an infrared optometer. Subjects were classified into three types: emmetropes (n = 18), early onset myopes (n = 18) and late onset myopes (n = 15). The relationship between accommodative adaptation and the onset age of myopia were compared. There was no statistical difference in the pre-task tonic accommodation among the three subject groups. However, the accommodative adaptation differed in the three groups during the 5 min post-task period. The average accommodative adaptation of emmetropia, early onset myopia and late onset myopia were 0.66, 0.27 and 1.19 D, respectively. Accommodative adaptation in the late onset myopia group was significantly higher than in the emmetropia group. Furthermore, the accommodative adaptation in the early onset myopia group was significantly lower than in the emmetropia group. Two possible aetiologies of myopia are discussed: one for the group which shows low accommodative adaptation that has no relationship with the age of onset and another for the group which shows high accommodative adaptation that has a relationship to an onset age of 15 years or later. The aetiology is also considered with regard to a potentiating chemical effect on the synapses of the ciliary muscle.

Accommodation, Ocular↗

PubMed2006

Awareness of illness in schizophrenia: associations with multiple assessments of executive function.

Though insight in schizophrenia is correlated with flexibility in abstract thought, it is unclear how differing dimensions of executive functions are linked to insight. Accordingly, the authors administered the Scale to Assess Unawareness of Mental Disorder and the Delis-Kaplan Executive Function System to 53 participants with schizophrenia spectrum disorders. Spearman Rho correlations revealed that symptom awareness was significantly related to Verbal Fluency, Color-Word, Tower, and Word Context scores. Awareness of treatment need was related to Color-Word, Tower, and Word Context tasks. Results suggest insight may be related to capacities to shift attention between differing environmental demands, plan ahead, and construct contextual understandings.

Adult↗

PubMed2006

MathDAMP: a package for differential analysis of metabolite profiles.

BACKGROUND: With the advent of metabolomics as a powerful tool for both functional and biomarker discovery, the identification of specific differences between complex metabolite profiles is becoming a major challenge in the data analysis pipeline. The task remains difficult, given the datasets' size, complexity, and common shifts in migration (elution/retention) times between samples analyzed by hyphenated mass spectrometry methods. RESULTS: We present a Mathematica (Wolfram Research, Inc.) package MathDAMP (Mathematica package for Differential Analysis of Metabolite Profiles), which highlights differences between raw datasets acquired by hyphenated mass spectrometry methods by applying arithmetic operations to all corresponding signal intensities on a datapoint-by-datapoint basis. Peak identification and integration is thus bypassed and the results are displayed graphically. To facilitate direct comparisons, the raw datasets are automatically preprocessed and normalized in terms of both migration times and signal intensities. A combination of dynamic programming and global optimization is used for the alignment of the datasets along the migration time dimension. The processed datasets and the results of direct comparisons between them are visualized using density plots (axes represent migration time and m/z values while peaks appear as color-coded spots) providing an intuitive overall view. Various forms of comparisons and statistical tests can be applied to highlight subtle differences. Overlaid electropherograms (chromatograms) corresponding to the vicinities of the candidate differences from any result may be generated in a descending order of significance for visual confirmation. Additionally, a standard library table (a list of m/z values and migration times for known compounds) may be aligned and overlaid on the plots to allow easier identification of metabolites. CONCLUSION: Our tool facilitates the visualization and identification of differences between complex metabolite profiles according to various criteria in an automated fashion and is useful for data-driven discovery of biomarkers and functional genomics.

Biomarkers↗