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Results for “Task Shifting”

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PubMed2001

The diagnosis and neuropsychological assessment of adult attention deficit/hyperactivity disorder. Scientific study and practical guidelines.

The recognition of attention deficit/hyperactivity disorder (ADHD) in adults is a well documented, but relatively new development. Investigations of the disorder have indicated that disturbances in behavior and adjustment are common. These disturbances may be linked to poorly developed executive functions. This paper reviews the neuropsychological studies that have compared persons with ADHD to normal controls and to psychiatric controls. The review indicates that persons with ADHD share many neuropsychological characteristics with other persons with serious psychiatric conditions, although those with ADHD may have a particular profile of slowed performance in tasks of sustained attention and set shifting, and their use of working memory may be particularly impaired. The implications of research for clinical assessment are discussed. We contend that a neuropsychological orientation is necessary for making the diagnosis and gaining a full understanding of adult ADHD. A model for clinical assessment is proposed which utilizes a neuropsychological orientation and the targeted administration of neuropsychological instruments. The careful use of neuropsychological measures is warranted in providing an elaborate picture of a person's functioning, although the use of neuropsychological tests is not necessary to make the diagnosis.

Adult↗

PubMed2004

Neuropsychological assessment of patients with late onset GM2 gangliosidosis.

OBJECTIVE: To characterize cognitive status in a sample of individuals with late-onset GM2 gangliosidosis (commonly referred to as late-onset Tay-Sachs disease). METHODS: Seventeen subjects (13 men, 4 women) diagnosed with GM2 gangliosidosis were evaluated. Subjects ranged in age from 18 to 56 years and were in various stages of disease progression. Subjects underwent comprehensive neuropsychological assessment. Impairment was defined as performance more than 1.6 SD below the normative mean. RESULTS: Group mean performance was within the denoted normal range on all measures except on a task assessing visual sequencing and set shifting. Approximately one-half of the sample scored in the impaired range on measures of processing speed, visual sequencing, and set shifting. One-third of the sample also scored in the impaired range on measures of delayed verbal recall. Impairment tended to be restricted to a subset of the sample, as 5 of the 14 subjects able to undergo formal testing accounted for 70% of the total number of impaired scores. If the three subjects unable to participate in formal testing are also considered impaired, 47% of the current sample exhibited significant cognitive impairment in at least one cognitive domain. CONCLUSION: In late-onset GM2 gangliosidosis, there is a risk of impairment in executive functioning and memory as well as cerebellar dysfunction. Dementia was not present in any subjects in the current sample.

Adolescent↗

PubMedDate not supplied

Design of primary nursing jobs in a paediatric unit.

Nursing jobs in the four wards of a paediatric unit were evaluated in a job diagnostic survey before the introduction of a primary nursing regimen. The approach used was a combination of task and patient allocation on a shift basis.

Hospital Units↗

PubMed1995

Stimulus-driven or autonomous shift or attention?

Hsieh and Allport studied shifts of attention in semantic space, using a semantic monitoring task based on rapid, serial, visually presented sequences of words. They reported that following a shift of criterion, accuracy of semantic monitoring dropped abruptly to a low level, then gradually recovered to reach the preshift level over successive stimuli in the sequence. They further examined the nature of the recovery of accuracy following a shift of criterion. Despite the striking results they obtained, some problems of their design remained. Hence, the current research replicated Hsieh and Allport's experiments with some modifications and showed that a shift of semantic criterion in a rapidly presented sequence indeed appears to be stimulus-driven rather than an autonomous process.

Adult↗

PubMed1997

Temporal binding errors are redistributed by the attentional blink.

When one searches for a target among nontargets appearing in rapid serial visual presentation (RSVP), one's errors in performance typically involve the misreporting of neighboring nontargets. Such illusory conjunctions or intrusion errors are distributed differently around the target, depending on task or stimulus variables. It is shown here that shifts in intrusion error patterns can be produced by the manipulation of attention alone. In a dual-task paradigm, the magnitude and distribution of intrusion errors changed systematically as a function of available attentional resources. Intrusion errors in RSVP tasks reflect internal capacity limitations for binding independent features. The present results support a two-stage model of RSVP target processing.

Adult↗

PubMed1999

On the role of feedback in promoting conflicting goals of the adaptive immune system.

We explored here the implications of two premises. 1) In their response over days or weeks to pathogen invasion, cells of the immune system combine several overlapping and perhaps contradictory goals. 2) The immune system has ways to monitor progress toward these goals via receptors that bind chemicals whose concentrations are related to such progress. We illustrate with simple mathematical models how such monitoring can lead to feedbacks that improve the efficiency of a given effector type in accomplishing its specialized task, and also how feedbacks can shift the balance among a variety of effectors toward a preponderance of the more effective. Specific suggestions are given for feedback molecules.

Animals↗

PubMed1996

[The colonial state and demographic knowledge in French West Africa, 1904-1960].

"Our lack of knowledge on the production of population estimates in France's colonial empire is in sharp contrast to the efforts of British authorities after 1940. To understand this ¿omission', we have to assess the numerous oppositions existing within the French colonial state.... After the first memoranda of 1904 and 1909, colonial census-taking activities were inexorably merged with everyday administrative tasks: taxation, justice, policing, etc. This shift clearly influenced the form and function of demographic knowledge in French West Africa (AOF).... We conclude with a mixed assessment of attempts to amass demographic knowledge and especially of the influence such knowledge actually had on decision-making." (SUMMARY IN ENG AND SPA)

Africa↗

PubMed2006

Why a system awarded as "MIE '99 Best Paper" failed to be used and hence to affect patient's health?

OBJECTIVE: The failure of a promising system is described with the aim of identifying the errors and the unfavourable conditions that led to such a result. METHODS: The system, based on the AHCPR guideline for pressure ulcers prevention and integrated into the already existing clinical information system, is aimed at supporting nurse's activities for: the risk assessment of the inpatient at the beginning of the hospitalization; the prevention plan, customized to each specific patient; the work plan for each day for all the patients; the report of the non-compliances to the GL and of the workload of the nurses. RESULTS: The system was abandoned after a short period. The reported reasons for the abandonment were: too strict constraints in the work-plan and the mandatory updating of the tasks at the end of each shift (both executed and not); the double writing activity, on paper first and afterward on the workstation. The first complaint was almost unrecoverable and not related to the system from the implementation point of view. Portable notebooks and wireless connections to the LAN could have been a solution for the second problem. Simultaneously a portable device at the bed side could have benefited many other features of the clinical information system. We proposed to quantify the added value, if any, due to making the information system available as close as possible to the points on the wards where information are both generated and used. The proposal was rejected. CONCLUSIONS: In our experience in a hospital setting, closing the gap among the medical informatics minority, the health professionals and the hospital management, through their collaborative responsibilities and participation in the decision-making process, can make the difference between the success and the failure of a good computer-based solution.

Awards and Prizes↗

PubMed1982

[The relation between workload and strain in the presence of severe physical disability-findings of a case study].

The workload on a physically disabled subject is compared to the load on a non-disabled subjects at identical tasks over a period of 5 shifts each. Various indicators for assessment of the physical working capacity as well as recordings of heart rates during activity are compared. The findings indicate that, in spite of comparable load, the strain may be greater for the disabled person than for the non-disabled, which does however not necessarily entail a difference in output.

Body Height↗

PubMed2002

Effects of task structure on category priming in patients with Parkinson's disease and in healthy individuals.

Lexical decision tasks have been used to study both shifts of attention and semantic processing in Parkinson's Disease (PD). Whereas other laboratories have reported normal levels of semantic priming among PD patients, our laboratory has reported abnormally large levels. In this study, two experiments were performed to determine the influence of task structure on the extent of semantic priming during lexical decision-making and pronunciation tasks among PD patients and neurologically healthy controls. In Experiment 1, the effect of Prime Dominance (the ratio of category to neutral trials) on lexical decision-making was studied. Although equal numbers of word and nonword trials were presented, half of the PD patients and controls were studied under Category Prime Dominance (category : neutral prime ratio of 2:1) and half were studied under Neutral Prime Dominance (category : neutral prime ratio of 1:2). In Experiment 2, PD and control participants were studied on lexical decision-making and pronunciation tasks where twice as many words as nonword trials were presented, consistent with other studies from our laboratory. In Experiment 1, we found no group differences in the magnitude of priming and no effect of Prime Dominance. Moreover, the findings were similar in pattern and magnitude to results published by Neely (1977). In Experiment 2, we observed larger priming effects among PD patients than among controls, but only on the lexical decision (LD) task. These results support the hypothesis that abnormally large category-priming effects appear in LD studies of PD patients when the number of word trials exceeds the number of nonword trials. Furthermore, increased lexical priming in PD appears to be due to processes operating during the decision-making period that follows presentation of the lexical target.

Aged↗

PubMed1998

Abstract and effector-specific representations of motor sequences identified with PET.

Positron emission tomography was used to identify neural systems involved in the acquisition and expression of sequential movements produced by different effectors. Subjects were tested on the serial reaction time task under implicit learning conditions. In the initial acquisition phase, subjects responded to the stimuli with keypresses using the four fingers of the right hand. During this phase, the stimuli followed a fixed sequence for one group of subjects (group A) and were randomly selected for another group (group B). In the transfer phase, arm movements were used to press keys on a substantially larger keyboard, and for both groups, the stimuli followed the sequence. Behavioral indices provided clear evidence of learning during the acquisition phase for group A and transfer when switched to the large keyboard. Sequence acquisition was associated with learning-related increases in regional cerebral blood flow (rCBF) in a network of areas in the contralateral left hemisphere, including sensorimotor cortex, supplementary motor area, and rostral inferior parietal cortex. After transfer, activity in inferior parietal cortex remained high, suggesting that this area had encoded the sequence at an abstract level independent of the particular effectors used to perform the task. In contrast, activity in sensorimotor cortex shifted to a more dorsal locus, consistent with motor cortex somatotopy. Thus, activity here was effector-specific. An increase in rCBF was also observed in the cingulate motor area at transfer, suggesting a role linking the abstract sequential representations with the task-relevant effector system. These results highlight a network of areas involved in sequence encoding and retrieval.

Adult↗

PubMed2006

Time-on-task effect in pseudoneglect.

Neurologically normal subjects systematically misbisect space during visual line-bisection or similar tasks, generally erring to the left of the veridical center when bisecting horizontal lines, a phenomenon referred to as pseudoneglect. This phenomenon is usually interpreted as enhanced attention toward the left hemispace resulting in an overestimation of the leftward extent of a line. While most studies have examined the role of attention in spatial bias using spatial cueing methods in bisection tasks, Manly et al. (Neuropsychologia 43(12):1721-1728, 2005) proposed an original paradigm in which the participants' alertness was diminished by sleep deprivation or prolonged execution of a line-bisection task. The authors reported a significant rightward shift in attention related to declining alertness, but they did not control eye movements and, consequently, modifications of scanning and fixation strategies with fatigue cannot be ruled out in their study. Here we examine whether a diminution in alertness induced by a 60-min-long Landmark task would diminish (or even reverse) this attentional bias, when eye movements are absent. Participants performed a forced-choice judgment about the location of a transaction mark in relation to the veridical center of a horizontal line. The results confirmed a significant decrease in the leftward bias over the course of the session but, in contrast to the findings of Manly et al. (2005), we did not observe a reverse bias from the left to the right hemispace. The results are discussed within the context of the hemisphere-activation model.

Adult↗

PubMed1994

The nature and processes of preverbal learning: implications from nine-month-old infants' discrimination problem solving.

Nine-month-old infants' performance on discrimination-learning problems was investigated in four experiments using the synchronous reinforcement paradigm. These experiments were organized around basic theoretical postulates concerning the relation between attention and learning. In each of the experiments, infants were trained to respond differentially to a particular stimulus feature, with the goal of establishing whether they could learn to respond to a particular stimulus feature under conditions where other stimulus dimensions were present and varying. In the first experiment, 48 infants were trained to fixate visually on a particular feature in a pair of stimuli that varied in color, form, and position dimensions. Contingencies for responding were then shifted either within a dimension (reversal shift) or across dimensions (nonreversal shift). Infants learned to respond to the reinforced feature during initial training; moreover, infants assigned to a reversal shift condition showed a higher level of transfer of learning during the test phase than those assigned to a nonreversal shift condition. The second experiment extended the results of Experiment 1 by testing 48 additional infants under conditions in which the number of varying irrelevant dimensions was increased during the shift phase. Although the difficulty added to this task by this manipulation made transfer more difficult for all infants, results again indicated that transfer of learning was more evident for infants in a reversal shift than a nonreversal shift condition. In the third experiment, 64 infants were trained in a similar manner, except that completely new values were substituted during shift phases on the color and form dimensions. This manipulation was meant to probe whether infants were formulating a dimension response from previous training and to test the predictions of such dimension processing for transfer of learning to a functionally new problem. Infants were reinforced for fixating on a new feature either within the same dimension as during training (intradimension shift) or within the dimension that was not originally trained (extradimension shift). Transfer of learning was clearly superior in the intradimension shift condition. The findings of the first three experiments suggested that, during discrimination-learning problems, infants selected and tested individual stimulus features and dimensions from an array of potential solutions to the problem until discovering the one that was consistently associated with reinforcement.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1977

Blood pressure and cardiac changes during signalled and unsignalled avoidance in dogs.

Alterations in blood pressure (BP) during two aversive behavioral tasks were studied in five chronically-prepared dogs. During a signalled-avoidance task, BP levels were not altered, although heart rate (HR) increased. While propranolol (0.3 mg/kg, IA) led to slight increases in resting pressure, and phenoxybenzamine (1.0 mg/kg) reductions, the tachycardia at avoidance onset was not affected. Exposure to an unsignalled-avoidance task led to elevated diastolic BP levels during a preavoidance period and to increases in systolic BP, HR and aortic dP/dt at the inception of the avoidance session. Again, neither drug affected the tachycardia during avoidance, but both agents precluded BP and aortic dP/dt increases. Patterns of intercorrelations among cardiovascular variables were similar for both tasks, and suggested that the basis of the BP maintenance shifted from vasomotor to cardiac control during the avoidance periods. The differential cardiovascular adjustments during these tasks could not be accounted for in terms of differences in response rate. Rather, the critical variable seemed to be the amount of feedback the animal received for responding.

Animals↗

PubMed2003

The costs of doing two things at once for young and older adults: talking while walking, finger tapping, and ignoring speech or noise.

Young and older adults provided language samples in response to questions while walking, finger tapping, and ignoring speech or noise. The language samples were scored on 3 dimensions: fluency, complexity, and content. The hypothesis that working memory limitations affect speech production by older adults was tested by comparing baseline samples with those produced while the participants were performing the concurrent tasks. There were baseline differences: Older adults' speech was less fluent and less complex than young adults' speech. Young adults adopted a different strategy in response to the dual-task demands than older adults: They reduced sentence length and grammatical complexity. In contrast, older adults shifted to a reduced speech rate in the dual-task conditions.

Adolescent↗

PubMedDate not supplied

Biofeedback produced slow brain potentials and task performance.

Twenty subjects learned to control slow potential (SP) shifts of the brain by means of a biofeedback procedure. Depending upon the pitch of a signal tone, negative SP shifts had to be increased or reduced during intervals of 6 sec each. Visual feedback of the actual SP shift was given. Blocks of training trials alternated with blocks of test trials without any feedback of the SPs. At the end of every test trial a simple arithmetic problem had to be solved by the subjects. Subjects performed the computation in a shorter time interval if an increased negativity preceded task onset as compared to slower response times during suppression of negativity. Results suggest that cortical negativity reflects unspecific preparation for cerebral performance.

Attention↗

PubMed2006

Changing channels: an fMRI study of aging and cross-modal attention shifts.

Age-related deficits in visual selective attention suggest that the efficiency of inhibitory processes is particularly affected by aging. To investigate whether processing inefficiencies observed in visual attention are similar in auditory attention and when shifting attention across modalities, we conducted an fMRI study with healthy young and older adults using a task that required sustained auditory and visual selective attention and cross-modal attention shifts. Older adults in this study performed as well as the younger adults, but showed age-related differences in BOLD responses. The most striking of these differences were bilateral frontal and parietal regions of significantly increased activation in older adults during both focused and shifting attention. Our data suggest that this increased activation did not reflect new recruitment, but reliance on brain regions typically used by younger adults when task demands are greater. Older adults' activation patterns suggested that even during focused attention conditions they were "shifting" attention to stimuli in the unattended modality. Increased activation during processing of both task-relevant and task-irrelevant information implies age-related loss of processing selectivity. These patterns may reflect both task-specific compensatory neural recruitment and degradation of sensory inhibition.

Acoustic Stimulation↗

PubMed2004

Attention and executive function deficits in chronic low-dose MPTP-treated non-human primates.

Parkinson's disease (PD) is a complex disorder consisting of motor deficits coupled with dysfunction in cognitive domains that are dependent upon the integrity of the frontal lobes and/or the fronto-striatal axis. Although it is increasingly acknowledged that PD patients have attentional and executive function deficits, it has been difficult to model these in nonhuman primates because of the nature of the cognitive tasks that have been used previously. The present studies were conducted to further define the nature of the cognitive impairment in a nonhuman primate model of early parkinsonism consequent to chronic low dose MPTP exposure and to further validate this model in monkeys trained to perform a battery of attentional and executive function tasks. Following chronic low dose MPTP exposure, monkeys developed deficits in maintenance of a response set as well problems in shifting attentional sets, suggesting decreased mental flexibility. On other tasks inattentiveness, an impaired ability to sustain spatial attention or to focus attention, a deficit in motor readiness and planning, and impaired time estimation were also observed. These results provide direct evidence of attention and executive function deficits in a nonhuman primate model of early parkinsonism. Based on these findings, we suggest that in addition to being useful for studying the cognitive deficits related to early PD and for developing new therapeutics for these problems, this model and these testing procedures may also provide a useful large animal model for studying attention deficit disorder and for developing new therapeutics for that condition as well.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗