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Results for “Task Shifting”

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At least 109 records · Page 6Linked to original sources

PubMed1979

Cerebral potentials during smooth goal-directed hand movements in right-handed and left-handed subjects.

During smooth goal-directed hand movements a negative potential shift can be recorded from the human scalp. This goal-directed movement potential (GDMP) is preponderant over central areas with a maximum at the vertex and, over the motor cortex, contralaterally larger than ipsilaterally to the moving hand. In 11 right-handed and 6 left-handed subjects, the morphology and distribution of these potential shifts were studied in relation to task differences, moving hand and handedness. The results show a functional differentiation of two components of the GDMP: (1), a lateralized, slow negative wave, restricted to the precentral area and selectively varying with the hand used, and (2), a widespread, bilateral symmetrical component, selectively influenced by task-specific and individual factors. Two effects reflect an influence of the subject's handedness on the GDMP: (A) averaged for both hand conditions, there are larger amplitudes over the hemisphere contralateral to the dominant hand, and (b), averaged for both hemispheres, larger amplitudes result from using the non-dominant hand.

Adolescent↗

PubMed1992

Late cognitive event-related potentials in adult Down's syndrome.

Event-related electroencephalogram (EEG) potentials (ERPs) using two different tasks were measured in 14 adults with Down's syndrome (DS; mean age 32 years) without clinically detectable cognitive decline. Two groups, young healthy (YH) and old healthy (OH) adults, served as controls. In the oddball task, DS had prolonged N1 and earlier P2 latencies than the control groups. P3 latency was delayed in comparison to YH. In the PushWait task, P3 latency was later in DS than in YH and OH. In both tasks, DS showed a marked amplitude shift towards positivity overlapping the N1-P2 complex and seemingly also P3: The P3 amplitude evoked by target tones and by "Push" was shifted towards anterior sites resulting in a Cz maximum. Changes of the N1 latency and amplitude in DS may be related to enhanced arousal during stimulus processing, indicating a possible defect of central inhibitory mechanisms. The study suggests that differentiated ERP procedures provide information on adult DS cognition exceeding those given by mere P3 latency measurements. Such procedures may be useful in the evaluation of the cognitive decline due to precocious aging or Alzheimer-type dementia in DS.

Adult↗

PubMed1992

EEG spectra in dyslexic and normal readers during oral and silent reading.

EEGs of extensively screened dyslexics and normal readers were recorded while they read easy and difficult texts silently and orally, and during two other verbal tasks which also differed in overt speaking but had no reading component: narrative speaking and listening to a story. Mid-temporal, central and parietal leads were referenced to linked ears and to Cz. Large differences between tasks and between groups were found. With the linked ears reference, power was higher in all bands in oral reading than in silent reading, with the largest change occurring in the temporal leads. In the theta and low beta bands the difference between oral and silent reading was greater for controls than for dyslexics. These effects were not accounted for by differences in reading speed or in difficulty. Similar results were found in two cohorts of subjects. The difference between groups in theta was found only in the reading tasks. In contrast, the group difference in low beta was also found in the change from listening to speaking. This implies that the oral-silent group difference in theta is related to some aspect of the reading tasks other than the presence or absence of overt speaking, and that the low beta group difference is related to some aspect of overt speaking rather than to reading per se. With the Cz reference no group differences were found. It is suggested that the groups differ in the reading strategies they use, and the degree to which they shift strategy between the silent and oral tasks. We hypothesize that these cognitive differences are reflected in the theta activity from the temporal lobe. While there were many differences between the tasks in alpha power and asymmetry, no group differences involving alpha were found.

Adolescent↗

PubMed1990

The effects of ibotenic acid lesions of the nucleus basalis and cholinergic-rich neural transplants on win-stay/lose-shift and win-shift/lose-stay performance in the rat.

Rats were trained to criterion performance in 2-lever operant conditional memory tasks that required them to follow either a Win-stay/Lose-shift, or else a Win-shift/Lose-stay response rule. Substantial impairments in performance of both pretrained conditional tasks were seen following ibotenic acid lesions of the nucleus basalis, but not of the globus pallidus. The deficit in both tasks was apparent at all inter-response retention intervals, indicating that nucleus basalis lesions produced a general impairment in the performance of the complex conditional operant tasks, and not a specific deficit in short-term memory. The nucleus basalis lesion rats were then divided into groups matched for equivalent performance. One group was given cell suspension grafts into neocortex of E15 cholinergic-rich forebrain tissue; a second group was given similar grafts of E17 hippocampal tissue; and a third group was given sham transplants. Testing beginning 3 months post-transplant showed that there was no evidence of recovery of performance on these tasks in the cholinergic-rich transplanted groups compared to the controls. However, the rats with cholinergic-rich transplants subsequently showed a significant improvement in retention of a step-through passive avoidance task. The results indicate that either cholinergic deafferentation of the neocortex is not critical for the observed deficits in the operant conditional tasks, or recovery of function following cholinergic-rich transplants is task-specific, in that more complex cognitive tasks may require different levels of graft-host neural integration.

Animals↗

PubMed1988

Negative cortical DC shifts preceding and accompanying simultaneous and sequential finger movements.

Cortical DC shifts preceding and accompanying the execution of five different bimanual motor tasks were analysed in 20 subjects. All tasks required repetitive flexions and extensions of the two forefingers for a period of at least six seconds. The temporal and spatial structures organization varied in the different tasks: (1) Simultaneous agonistic performance (forefinger flexion on both sides), (2) simultaneous antagonistic performance (e.g. flexion of the right, extension of the left forefinger), (3) sequential agonistic performance, (4) sequential antagonistic performance, (5) uncoordinated flexions and extensions of the two forefingers. Compared to (1) and (2), conditions (3) and (4) included a temporal delay between the performance of the two forefingers; compared to (1) and (3), conditions (2) and (4) required the subjects to perform movements of opposite directions with their two forefingers. Effects of the temporal factor (T; simultaneous vs. sequential) and the spatial factor (S; agonistic vs. antagonistic) on cortical DC shifts were investigated. The voluntary initiation of each motor task was preceded by a Bereitschaftspotential (BP). The performance of the complex tasks (1-4) was accompanied by a slow negative DC potential shift (N-P). In general, the BP did not differ depending on the temporal or spatial structures of the tasks (1-4). However, amplitudes of N-P (i.e. during tasks) were influenced by the temporal factor with significantly larger amplitudes in sequential than in simultaneous tasks. This difference was not a global phenomenon in all recordings but was selectively found in the recordings over the fronto-central midline.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

[Occupational medicine and occupational science evaluation of shift work systems with integrated 12-hour shifts].

A field study was performed on 32 male deep drilling workers engaged in hard physical work and 10 male operators with mainly supervisory tasks; both groups working in a shiftwork system including 12 hr shifts. Both the analysis and evaluation of stresses and strains were carried out by means of physiological, psychological and sociological methods. The obtained results show that under the conditions of the given working requirements, existing reproduction conditions, and observed social structure of the populations operating and supervisory activities in a 8 hr shiftwork system including 12 hr shifts are acceptable. In case of hard physical work this shiftwork arrangement can't be agreed to for industrial-medical reasons.

Adult↗

PubMed1990

Sparing of attentional relative to mnemonic function in a subgroup of patients with dementia of the Alzheimer type.

Patients with dementia of the Alzheimer type (DAT) received two tests of visual selective attention, together with tests of spatial and visual recognition memory and visuospatial conditional learning previously used to show deficits early in the course of DAT. One set of attentional tests compared visual discrimination learning along intra- and extra-dimensional shifts, using a "total change" design. In the 12 DAT patients capable of attempting the extra-dimensional shift (subgroup 1), performance was equivalent to that of controls. This subgroup was also unimpaired at simple and compound discrimination learning and reversal and an intra-dimensional shift. They were as accurate as controls on a visual search task requiring matching of stimuli on two dimensions with variable numbers of alternatives, but were significantly impaired in the tests of recognition memory and learning. By contrast, the other 13 patients showed marked impairments in the attentional tasks. This subgroup was also significantly worse than subgroup 1 in performance on the visual recognition and conditional learning tasks, and showed greater severity on most of the clinical ratings of dementia. The sparing of attentional shifting in patients early in the course of DAT is contrasted with the impairments previously described in patients with Parkinson's disease with only mild or absent memory loss. The implications of this double dissociation of deficits for understanding the neural bases of the cognitive deficits in these two neurodegenerative diseases are discussed and their significance for the staging of DAT is considered.

Aged↗

PubMed1989

Cerebral lateralization of music perception in the dual task paradigm: unfamiliar melody recognition in sinistrals.

A dual task study of unfamiliar music perception during concurrent right and left hand finger tapping was conducted with a group of left-handed non-musicians. A pattern of symmetrical, bilateral suppression of finger tapping was observed during a concurrent music task of unfamiliar melody recognition. There was no evidence of trade-off effects in the dual task inasmuch as no interference in melody recognition was observed. The absence of attentional shifts strongly suggests that the bilateral symmetry in motor performance in the dual task condition reflects bilateralized cerebral organization among sinistrals for processing unfamiliar music.

Adult↗

PubMed1991

Desynchronization of oral temperature, pulse and performance circadian rhythms in shift working Indian nurses.

Circadian time structure in shift working Indian nurses was studied. In shift workers desynchronization between circadian rhythms in different physiological variables was observed. Circadian amplitudes of oral temperature, pulse and random add speed rhythms decreased significantly in shift workers as compared to control subjects. Circadian mesors of performance rhythms increased significantly in shift workers indicating that the time taken by them was more for performing the tasks. It can be concluded that the subjects studied herein are intolerant to shift work and amplitude decrement may be considered as a chronobiologic index to determine the tolerance of individual workers to shift work.

Adult↗

PubMed1990

Comparison of lingual vibrotactile suprathreshold numerical responses in men and women: effects of threshold shift during magnitude-estimation scaling.

The purpose of this study was to investigate differences in tactile sensory system function between men and women. This task was accomplished by studying the effects of possible tactile threshold shifts occurring during magnitude-estimation scaling of vibratory stimuli presented to the dorsal surface of the tongue. 12 men (M age = 19.7 yr.) and 12 women (M age = 19.3 yr.) participated. Analysis suggested that men and women have tactile sensory systems that operate similarly at both threshold and suprathreshold levels of stimulation. Men and women do, however, choose to use consistently different numerical responses to suprathreshold stimuli, suggesting that environmental and/or cultural-educational influences may be involved in numerical decision-making aspects of the scaling process.

Adolescent↗

PubMed1989

[Occupational medicine outpatient management of shift workers].

Proceeding from the reasons why the amount of multi-shift work has to be increased further, the tasks of works doctors and research work in the field of industrial medicine are pointed out in this paper. The evaluation of 200,000 medical fitness and follow-up examinations annually and the present results of research work give reasons for revising the examination category "shift workers" in the legal regulations of the medical fitness and follow-up examinations which are being revised as well as orienting and concentrating on certain main fields of research.

Adult↗

PubMed1990

The nature of selective attention effects on auditory event-related potentials.

The purpose of the research reported here was to examine a number of issues relating to the nature of selective attention effects on auditory event-related potentials (ERPs), namely, to determine the relative contribution of N1 and slow wave (SW) to the early and late components of Nd respectively, where Nd is defined as the negative shift of attended ERPs relative to unattended ERPs; to examine whether individual differences in Nd morphology are related to performance and the strategies that subjects use; and to determine the contribution of changes in the attended and unattended ERPs to Nd. Auditory ERPs were recorded from subjects as they carried out an auditory selective attention task and a visual target detection task. The auditory selective attention task was a multidimensional task in which stimuli varied on location, pitch and duration and in which the subject's task was to pay attention to a particular location/pitch combination and respond whenever they detected a long-duration target tone. In the visual target detection task, subjects were required to respond whenever they detected a colour change in a light-emitting diode which also acted as a fixation point. Auditory ERPs recorded during the visual task were used to provide a measure of exogenous components uncontaminated by differential effects of selective processing of auditory stimuli. The results suggested that early Nd and N1 are independently generated as Nd did not exhibit the contralateral scalp focus typical of N1, and that late Nd is independent of SW. While substantial differences in Nd morphology were observed over subjects, these differences showed no consistent relationships to performance or to task strategies. Comparison of auditory ERPs during active auditory attention with auditory ERPs recorded during the visual control task indicated that there was an early negative shift of the attended ERP, a later negative shift of the attended ERP which had a frontal focus and a later positive shift of the unattended ERP. These results suggest that there are active processes involved in the processing of stimuli from both the attended and unattended source.

Adolescent↗

PubMed1990

The function of self-touchings, posture shifts, and motor discharges in children from 3 to 6 years of age.

The function of self-touchings, posture shifts, and discharges was studied by comparing videotapes of 48 normal children aged 3 to 6 yr. performing on two tasks, watching cartoons and telling about these cartoons. We scored the occurrence of self-touchings, posture shifts and discharges by 5-sec. intervals on both tasks. We could not find developmental changes between 3 and 6 yr. of age, but significant differences in the numbers of movements between watching and telling appeared. Children moved much more during telling than during watching cartoons. This was interpreted as a reflection of task-specific attention in watching and telling. The attention-regulating function of the behavior was further shown by an outburst of movements during the first 10 sec. after the start of watching each cartoon. Self-touchings, posture shifts, and discharges seem to be part of the 'orienting reflex'.

Arousal↗

PubMed1989

Probability matching in visual selective attention.

Jonides (1980, p. 111) suggested a model to account for shifts of spatial attention in visual search tasks with less than 100% cue validity. This two-stage probability matching model was subsequently tested by Jonides (1983). Reaction time distribution characteristics indeed provided some support for the model. In the present paper the relevant data presented in Jonides (1980, 1981, 1983) are further analysed. The results of this analysis strongly support the probability matching hypothesis. Probability matching is apparently a very important strategic characteristic of visual spatial attention that deserves much more study.

Attention↗

PubMed1990

Agarose gel electrophoresis of linear genomic DNA in the presence of ethidium bromide: band shifting and implications for forensic identity testing.

We demonstrate that agarose gel electrophoresis of linear duplex DNA in the presence of ethidium bromide has a marked effect on the mobility of genomic DNA fragments detected by Southern hybridization. Mobility shifts of greater than 6% of the actual molecular weight were detected when different amounts of the same DNA sample were analyzed in 1.0% agarose gels containing 0.5 micrograms ml-1 ethidium bromide. For forensic applications, shifts of this magnitude could complicate the task of comparing restriction fragment length polymorphism profiles and introduce a degree of uncertainty to allele frequency population databases.

DNA↗

PubMed1990

Implementing a unit-based quality assurance program.

QA yields opportunities to improve patient outcomes as well as to identify problem areas. QA activities work when they are planned, systematic, organized, and ongoing. Monitoring is most easily completed concurrently by staff as part of their everyday activities rather than as an extra task to be done after a regular shift. Since staff nurses are the primary caregivers in this institution, a unit-based model for QA, where staff take the responsibility, yielded the best overall improvements in patient outcomes and quality of care.

Attitude of Health Personnel↗

PubMed1991

The effects of voluntary lateral orienting on positive manifold for lateralized cognitive tasks.

As an extension of previous studies (Urbanczyk, Angel, & Kennelly, Brain and Cognition, 8, 206-226) examining the effects of unimanual tapping on lateralized cognitive tasks, lateral body orienting was added to an established dual task paradigm to generate differential hemispheric activation and shifts of attention. One hundred twenty right-handed university students retained sequences of digits or spatial locations for 20 sec either alone or during finger tapping. By turning head and eyes left or right, the hemisphere congruent with the sequences (LH for digits, RH for locations) or incongruent (vice versa) was activated. Activation had little effect on retention means but greatly affected resource composition, supporting task performance. Congruent orientation produced significantly higher positive correlations between digit and location tasks than incongruent orientation. Females showed higher sequence retention correlations than males across both orienting groups. For females, congruent activation enhanced tapping rates and tapping-retention task correlations. For males, activation affected neither of these. These results suggest that congruent attentional orienting may couple or integrate regions of the less activated hemisphere into networks of the more activated hemisphere. Greater inter- and intrahemispheric connectivity in the female cortex may produce a greater dependence upon a general attentional "resource."

Adult↗

PubMed1989

Alertness of night nurses: two shift systems compared.

The alertness of hospital trainee nurses during their night shift work was assessed by recording performance at night on an arousal-sensitive unprepared simple reaction time task. One group carried out a number of separate weeks on night shift throughout their three-year course. Here performance fell from first to seventh day of the week on night shift, implying progressive sleep deprivation. Another group covered their night work by a single three-month 'permanent' night shift of four (or three) nights on and three (or four) days off each week. Here initial performance level fell by the 45th night but had returned to normal by the last (90th) night. In both systems individuals varied considerably in their ability to maintain performance during sustained night work. These results strengthen the case for permanent night shifts, with careful selection of personnel, as a means of organizing night nursing in hospitals.

Arousal↗