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Results for “Task Shifting”

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PubMedDate not supplied

[Work-related musculoskeletal disorders of the upper extremity in spinning: lack of risk or of adequate methods for assessing risk?].

The existence of a risk of musculoskeletal disorders work-related of the upper extremity (UEWMSDs) in the textile industry, specifically in particular working phases as spinning, appears today controversial. The upper limb disorders, sometimes described, have not a location ever plausible with the level of the biomechanical overload, as when carpal tunnel syndromes are signalled during activities in which the shoulder is the only segment eventually interested. Moreover these findings are shown in workers appointed at tasks or actions not clearly identified at risk. For example the spinning activity, that requires the movement of shuttles of modest weight, sometimes on levels above the shoulder line, is organized with cyclical cadences sometimes as repetitive tasks concentrated in a short period, sometimes in longer during the entire shift. Distribution and number of the actions, would however allow a sufficient biomechanical recovery. The identification of the single technical action may result difficult, due to interindividual variability of actions, of their speed and complexity. Furthermore the other possible activities, alternate with specific spinning activities, can require strength or not correct posture even if they may have short duration. In this paper we present and discuss the results of the ergonomic survey for risk assessment of musculoskeletal disorders work-related of the upper limb. These analysis have been carried out in two textile plants, in which some cases of disorders of the upper limb in workers employed in spinning activities have been described by occupational health physicians. In addition to assessment of possible risk for UEWMSDs in spinning activities, we founded the capability of usual methods for ergonomic analysis to adequately examine work situations like spinning, in which the hazardous actions are diluted over the entire shift or concentrate in a short period and in which there is a specific biomechanically overloaded segment i.e. the shoulder. Finally attention was paid to evaluate psychosocial factors which appear to be important when biomechanical factors are low-lying.

Arm↗

PubMed1997

Using two preferred retinal loci for different lighting conditions in patients with central scotomas.

PURPOSE: Using a scanning laser ophthalmoscope, it was found that some patients with relative central scotomas reliably used two different preferred retinal loci (PRLs) at different stimulus illuminances. This article describes adaptations in a patient's PRL for fixation when dimming the stimulus increased the relative scotoma size. METHODS: Twenty-eight patients with macular diseases had their dense and relative macular scotoma borders mapped with the scanning laser ophthalmoscope. The high-illuminance PRL (PRLhi) and low-illuminance PRL (PRLlo) were operationally defined as the PRLs that patients used to fixate a high or low illuminance stimulus, respectively. The PRLs' abilities to do visual tasks and their characteristics at the corresponding illuminances were assessed. RESULTS: The PRL consistently shifted between the PRLhi and the PRLlo as the stimulus illuminance was changed. Brightness permitting, the visual system prefers to use the PRLhi with generally better performance in visual function such as fixation stability. There were no significant differences between the PRLhi and the PRLlo in pursuit and saccadic abilities, when assessed by subjective ratings. The illuminances that induced shifting ranged from 106 to 3437 trolands. The PRLhi was always located within an area of relative scotoma, usually at the fovea or just outside a dense scotoma. The PRLlo was located in relatively healthy retinal area, and usually below or to the left of the PRLhi in the visual field. CONCLUSIONS: In the visual system, two well-defined PRLs can develop when visual function is adapting to maculopathy, with the use of each depending on the brightness of objects used in visual tasks. Rehabilitation and treatment strategies should consider the existence of multiple PRLs.

Adaptation, Ocular↗

PubMed1993

Contrasting mechanisms of impaired attentional set-shifting in patients with frontal lobe damage or Parkinson's disease.

Tests which assess the ability to shift cognitive set modelled after the Wisconsin Card Sorting Test are particularly sensitive to impairments in patients with Parkinson's disease as well as in patients with frontal lobe damage. However, the underlying mechanisms responsible for the similar deficits observed in the two patient groups are not well understood and may not be identical. For example, an apparent deficit in set-shifting ability may reflect either an impairment in the ability to shift from a perceptual dimension which has previously commanded attention (i.e. 'perseveration'), or in the ability to shift to an alternative perceptual dimension which has previously been irrelevant (i.e. 'learned irrelevance'). In this study, the performance of both medicated and non-medicated patients with Parkinson's disease were compared with a group of neurosurgical patients with localized excisions of the frontal lobes on a novel task designed to assess the relative contribution of 'perseveration' and 'learned irrelevance' to impaired set-shifting ability. Patients with frontal lobe damage were worse than controls in their ability to shift attention from a previously relevant stimulus dimension. Medicated patients with Parkinson's disease were worse at shifting to a previously irrelevant dimension. In contrast to both groups, nonmedicated patients with Parkinson's disease were impaired in both conditions. These results suggest that the gross set-shifting deficits reported in both frontal lobe patients and patients with Parkinson's disease may involve fundamentally different, though related, cognitive processes, and that these may be differentially affected by medication. Specifically, L-dopa therapy may protect Parkinson's disease patients from preservation of attention to a formerly relevant stimulus dimension.

Aged↗

PubMedDate not supplied

Aide for a day.

The author worked for an 8-hour shift in the role of nursing assistant at a skilled nursing facility as an additional provider over and above the usual staffing. The purpose of this exercise was (1) to demonstrate to nursing assistants the respect of administration for their work, (2) to gain firsthand insights into the specific tasks they perform, and (3) to describe potential inefficiencies and barriers to providing care. Following the shift, the author provided a written report to the administrator and the director of nursing describing the shift and making clinical and programmatic recommendations.

Journal Article↗

PubMed1998

Gaze and retinal-image-stability in two kinds of sequential looking tasks.

UNLABELLED: Eye and head movements used to keep the gaze on target were examined as unrestrained seated subjects performed two tasks: (1) tapping sequences of 3-D targets; and (2) only looking at sequences of 3-D targets. Large differences were observed in the head/eye coordination patterns used in each task. During tapping, the head moved quickly and continuously. Retinal-image speeds were relatively high (up to 5 degrees/s). During looking-only, the head moved more slowly and almost came to rest between gaze-shifts. Retinal image velocities between gaze-shifts were 60-77% lower during looking-only than during tapping. CONCLUSION: coordinated eye/head patterns are adjusted to satisfy the demands of a particular task. These adjustments affect low-level oculomotor mechanisms between as well as during the gaze shifts, themselves (reported previously).

Algorithms↗

PubMed1992

Expectancy and stimulus frequency: a comparative analysis in rats and humans.

We examined whether expectancy, one of several factors influencing attention, is similarly affected in rats and humans by manipulation of relative stimulus frequency. A two-choice reaction time (RT) task was developed for rats, and an analogous task was used for humans. Errors, RTs, discriminability, and response bias were measured. Both rats and humans shifted their response bias to the more frequent stimulus, with no change in overall discriminability. As stimulus probability or stimulus repetition increased, RTs and errors decreased. These results illustrate the similarity of expectancy in rats and humans. This two-choice RT task for rats can be used in future studies to examine the neuronal mechanisms of expectancy and attention.

Animals↗

PubMed1994

Spatial water maze learning using celestial cues by the meadow vole, Microtus pennsylvanicus.

The Morris water maze is widely used to evaluate to evaluate the spatial learning ability of rodents under laboratory settings. The present study demonstrates that reproductive male meadow voles, Microtus pennsylvanicus, are able to acquire and retain a spatial water maze task using celestial cues. Voles were able to acquire a modified outdoor Morris water maze task over 4 trials per day, whereby they had to learn and remember the location of a submerged hidden platform, using the position of the sun and associated celestial cues. Their proficiency on this task was related to the availability of the celestial cues, with voles displaying significantly poorer spatial navigation on overcast than clear days and when the testing time (and position of the sun and associated celestial cues) was shifted from morning to afternoon. These findings with meadow voles support the ecological relevance of the water maze task.

Animals↗

PubMed2003

Phase-shifting windowed Fourier ridges for determination of phase derivatives.

Determination of the phase or phase derivative from interferometric fringe patterns is an important task in optical interferometry. The use of wavelet ridges was recently shown to be an effective method for phase retrieval from a single fringe pattern. One necessary requirement in this method is the need for carrier frequency. In cases when carrier frequency is not available, the novel phase-shifting windowed Fourier ridges method can be used. Phase derivatives with the proper sign can be directly retrieved even in the presence of noise. An application for curvature determination from speckle shearographic fringes demonstrates the effectiveness of the method.

Journal Article↗

PubMed1994

P3 event-related potentials and performance of young and old subjects for music perception tasks.

Event-related potentials and performance data were recorded from young and old subjects performing six tasks involving auditory discrimination of musical stimuli. Tasks included pure tone, timbre, rhythm, and interval discrimination, detection of a meter shift, and discrimination of open and closed harmonic endings for chord progressions. P3 latencies were generally longer for the old subjects. P3 amplitude and performance differences between subject groups were not significant. Our results provide a quantitative probe of the neural and behavioral significance of the influence of aging and stimulus complexity on the processing of some of the elementary constituents of music. In particular, pure tone and timbre discrimination appear to correspond to behaviorally and neurally simpler processing than does discrimination of the other musical constituents tested in our study.

Adolescent↗

PubMedDate not supplied

Cognitive impairment after unilateral hemispheric injury of congenital or adult origin.

OBJECTIVE: The purpose of this study was to assess and compare cognitive functioning in adults with unilateral hemispheric injury due to either congenital damage or an ischemic event in young adulthood. METHOD: Adults with cerebral palsy resulting from left hemispheric brain damage were compared with adults who had a unilateral stroke in either the left or the right hemisphere. Our primary interest was to determine the impact on hemispheric dominance as revealed by dichotic listening, a task that assesses the bias for preferential listening and processing of sounds. Performance also was determined on a language-related task (word finding) and a spatial task (dot localization). RESULTS: Scores on the Quick Neurological Screening Test indicated that all participants demonstrated significant neuromotor deficits, whereas scores on the Barthel Index indicated that the participants were functional in basic activities of daily living. On cognitive assessments, healthy control participants demonstrated a pronounced left-hemisphere dominance and right-ear advantage; participants with injury to the left hemisphere showed a strong shift toward a right-hemisphere and left-ear dominance. In particular, injury of congenital origin appeared to foster this neural reorganization and localization of language-related functions into the healthy hemisphere. This shift was associated with a deterioration of performance on both the language and the spatial tasks. CONCLUSION: The importance of appreciating subtle deficits after unilateral injury is important in therapy. The dichotic listening test may provide a simple and useful means for evaluating persistent unilateral brain dysfunction in the clinical setting.

Adult↗

PubMed1994

Does implicit memory extend to legal and illegal nonwords?

In 4 experiments, implicit and explicit memory for words and nonwords were compared. In Experiments 1-2 memory for words and legal nonwords (e.g., kers) was assessed with an identification (implicit) and a recognition (explicit) memory task: Robust priming was obtained for both words and nonwords, and the priming effects dissociated from explicit memory following a levels-of-processing manipulation (Experiment 1) and following a study-test modality shift (Experiment 2). In Experiment 3, priming for legal and illegal nonwords (e.g., xyks) was observed on an identification task, and the effects dissociated from explicit memory following a levels-of-processing manipulation. Finally, in Experiment 4, significant inhibitory priming for legal nonwords was observed when a lexical-decision task was used. Results suggest that implicit memory can extend to legal and illegal nonwords. Implications for theories of implicit memory are discussed.

Acoustic Stimulation↗

PubMed2000

Antidepressant-like effects of pregnancy and progesterone in Wistar rats as measured in the differential reinforcement of the low-rate 72 s task.

RATIONALE: In rats, several behavioral changes occurring during pregnancy could be due to the presence of progesterone; some of them may be analyzed in the differential reinforcement of the low-rate 72 s task (DRL-72 s), which is designed for testing the antidepressant profile of drugs. OBJECTIVES: The aim of the present study was to analyze the behavior of pregnant rats or ovariectomized rats receiving exogenous progesterone in the DRL-72 s task. HYPOTHESIS: During pregnancy, rats will obtain a high number of reinforcers in the DRL-72 s task. METHODS: Pregnant rats or rats after delivery were tested in the DRL-72 s task at the 3rd, 7th, 14th, 17th, and 20th days. Control rats previously trained in the DRL-72 s task were ovariectomized; after recuperation, they received saline (0.9%, i.p.), clomipramine (1.25 mg/kg, i.p.), or desipramine (2.14 mg/kg, i.p.) for 28 days, and they were tested in the DRL-72 s task. In a second series of experiments, ovariectomized rats received vehicle or progesterone (0.5, 1.0, 2.0, 4.0 mg/kg, s.c.), and they were submitted to the DRL-72 s task. Locomotion was evaluated in the open field test. RESULTS: Pregnant rats tested at the 14th and 17th day and ovariectomized rats receiving progesterone or two tricyclic antidepressants obtained a higher number of reinforcers and a cohesive rightward shift in inter-response time distributions than those rats evaluated after delivery in the DRL-72 s task. A lower locomotion was observed only at the end of pregnancy. CONCLUSIONS: Antidepressant-like effects of pregnancy and progesterone were found in Wistar rats as measured in the DRL-72 s task.

Animals↗

PubMed1995

The effects of nightwork on psychological changes during the menstrual cycle.

This study investigated whether the temporal stress of working at night interferes with nurses' experience of different phases of the menstrual cycle. Twenty-four, rotating-shift nurses recorded data on a hand-held computer at the start and end of each day and every 2 hours during their shifts for a period of 28 days. The measures included a sleep diary, self-ratings of mood and symptoms, and two cognitive performance tasks. Using a pooled time series analysis, it was found that some of the self-report measures showed a significant interaction between type of shift worked and menstrual cycle phase. For example, alertness was found to be lower towards the end of the night shift during the premenstrual phase compared to other phase and shift combinations. However, some of the measures showed only main effects of cycle phase or were non-significant. Retrospective measures from a larger sample showed an association between the number of nights worked per year and duration of premenstrual and menstrual problems, and severity of premenstrual problems. The results suggest that nightwork may alter some aspects of nurses' psychological experience of the menstrual cycle.

Adult↗

PubMed1990

[Robustness of the analytic/holistic processing strategies in various cognitive tasks].

Robustness of the analytic/holistic processing strategies was examined in various cognitive tasks. The tasks in Experiment I were to classify facial patterns and verbal materials of different category structures into two categories. Stimuli were presented either with (thematization condition) or without a theme. Three types of strategies were discerned; consistently-analytic, consistently-holistic and optimal shifting. Experiment II was designed to test their performance in the Kagan type perceptual and memory identification tasks. The results from the two experiments showed that about 30% of the subjects adhered to either analytic or holistic strategy across tasks and experiments. They exhibited responses similar to the reflective and impulsive types. Approximately 40% of the subjects adjusted their strategies according to the task demands.

Acoustic Stimulation↗

PubMed1983

Frontal hemispheric differences in the Bereitschaftspotential associated with writing and drawing.

Twenty right-handed subjects participated in a study investigating the cerebral potentials related to three complex actions: (1) writing one's own signature, (2) drawing a pentagram, and (3) fast meaningless scribbling. The Bereitschaftspotential (BP, readiness potential) started as early as 3 s prior to writing, 2.5 s prior to drawing, but only 1.5 s prior to scribbling. In all three tasks, the BP had its earliest onset over the supplementary motor area (SMA). BP topography was shifted towards the frontal lobes when compared to encephalographic activity reflecting simple finger movements, and was very weak in retro-rolandic leads. The side of the performing hand, as assessed from scribbling, was reflected in a contralateral preponderance of the precentral BP. The maximum BP (about 6 microV) was, in all three tasks, located in FCz (mid fronto-central) overlying the SMA. This location is different from that for simple finger movements, when the maximum is at the vertex. Hemispheric differences were found over the frontal cortex and were characteristic for the verbal and spatial tasks involved: for writing, the BP was significantly larger left frontally than right (even after considering the effect of the performing hand from scribbling), and the difference was largest prior to the onset of movement; for drawing, the BP was larger over the right than over the left frontal lobe, and the difference was largest during the movement.

Action Potentials↗

PubMed2006

Neural correlates of verbal semantic memory in patients with temporal lobe epilepsy.

Functional imaging data suggest that the core network engaged in verbal semantic memory (SM) processing encompasses frontal and temporal lobe structures, with a strong left lateralization in normal right handers. The impact of long term temporal lobe epilepsy (TLE) on this network has only partly been elucidated. We studied verbal SM in 50 patients with chronic, intractable TLE (left TLE=26, right TLE=24) and 35 right handed normal controls using a verbal fMRI semantic decision paradigm. All patients had language lateralized to the left hemisphere, as verified by the intracarotid amobarbital procedure. Within and between group analyses showed remarkable, group-specific activation profiles. The control group activated frontal and temporal areas bilaterally, with a strong left predominance. Left TLE patients showed a shift of activations of left frontal and medial temporal areas to homologous regions in the right hemisphere. Furthermore, left TLE subjects utilized subcortical structures such as the thalamus and putamen to accomplish the verbal SM task. Contrastively, the activation pattern of right TLE patients resembled that of normal controls, but exhibited "hypofrontality" with a shift from frontal to posterior regions in the temporal, parietal and occipital lobe. Our results show that chronic epileptic activity originating from temporal seizure foci is associated with an alteration of neural circuits which support semantic language processing and that side of seizure focus has a specific impact on the resulting activation network. These findings presumably result from morphological changes and from functional reorganization which are both inherent to chronic TLE.

Adult↗

PubMed1980

Dorsal noradrenergic bundle and selective attention in the rat.

The role for the dorsal noradrenergic bundle (DNB) in selective attention and stimulus filtering was tested in several situations. The DNB was damaged by stereotaxically guided injections of 4 microgram of the neurotoxin 6-hydroxydopamine (6-OHDA). The latent inhibition effect was blocked by 6-OHDA-induced depletion of forebrain noradrenaline, whereas nonreversal shift performance was better in noradrenaline-depleted rats than controls. These data are interpreted to indicate that animals with DNB lesions are imparied in ignoring irrelevant stimuli. However, in situations in which control animals did not learn to ignore irrelevant stimuli, no lesion-induced difference was found. Thus, controls and animals with DNB lesions learned equally about each of two dimensions of a multiple-redundant discrimination task. This was assessed both by interpolated trials with only one dimension present and by shifts in which only one of the previous two dimensions remained relevant. It is concluded that the DNB lesion does not increase stimulus sampling globally but that it impairs performance only in those cases in which normal rats learn to ignore irrelevant stimuli.

Animals↗

PubMed1997

Event-related potential negative shift in sons of polysubstance- and alcohol-use disorder fathers.

Previous research has considered event-related potentials (ERPs) in relation to liability for alcohol and other substance use. This study explored ERPs in preadolescent boys at elevated risk for substance use due to paternal history of substance abuse or dependence. Sons (age 10-12) of fathers with an alcohol-use disorder (ALC, n = 29) were matched by age, IQ, education and parental alcohol use with sons of fathers with a polysubstance abuse or dependence diagnosis (POLY, n = 37). These two groups were matched with a low-risk comparison group (LOW, n = 29) of boys whose fathers had no substance-use disorder diagnosis. No boy in the study met criteria for a substance-use disorder. ERPs were collected from midline (Fz, Cz, Pz) and parietal (P3, P4) electrode leads during an auditory oddball task. ERPs of boys from the ALC and POLY groups showed a slow negative shift prominent at Cz and Pz. This negative shift, evident by 100 ms post-stimulus and lasting for the duration of the 1000-ms recording period, overlapped temporally with N1, N2 and P3 amplitude differences distinguishing the ALC and POLY groups from the LOW group. The ALC and POLY groups differed from each other in N2 amplitude at Cz, which was larger for ALC subjects. These findings offer a possible alternative explanation for previously observed amplitude anomalies noted in children at risk for substance-use disorders and suggest new avenues of inquiry.

Alcohol-Related Disorders↗