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Results for “Task Shifting”

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PubMed1985

Visual overselectivity: a comparison of two instructional remediation procedures with autistic children.

The present study compared two classroom-relevant procedures for remediating visual overselectivity in autistic children. One approach was based on perceptual-motor theory in which possible relationships between functional object-use and overselectivity were studied. The second strategy, equivalence training, used a four-step stimulus shift procedure. A comparison group of autistic children was exposed to simple repeated practice trials with the test tasks. Results showed that equivalence training was more effective than functional object-use in improving posttest scores, with repeated practice falling in between. The results are discussed in terms of theoretical and practical issues relating to stimulus overselectivity, including the incorporation of microcomputer technology.

Adolescent↗

PubMed1997

Chronic alcohol abuse and the acute sedative and neurophysiologic effects of midazolam.

The aim of the present investigation was to examine benzodiazepine sensitivity in abstinent alcoholics. For this purpose, two escalating doses of the benzodiazepine midazolam were i.v. administered to nine alcohol-dependent patients after 2-3 weeks of abstinence and 12 healthy, non-alcoholic volunteers. A variety of dependent measures were examined, including the power spectrum of the resting electroencephalogram (EEG) and evoked EEG responses, saccadic eye movements, self-reported sedation, and vigilance task performance. Analyses revealed a significant association between plasma midazolam levels and changes in EEG beta power, pattern shift visual evoked potential amplitude, heart rate, and saccade amplitude and velocity. The patient and control groups differed significantly in the onset latencies of their saccadic eye movements, and marginally in EEG beta power, both before and after midazolam. However, no differences were detected between the groups in the dose of midazolam required to produce sedation or in midazolam's neurophysiological effects.

Adult↗

PubMed1979

Role of the inferotemporal cortex in visual selective attention.

Electrocortical recordings were made from monkeys performing in a multidimensional visual task. Wave forms dependent on the stimulus presented (irrespective of task required) were recorded immediately following the stimulus primarily from electrodes implanted in the striate and prestriate cortex. Wave forms dependent on the panel pressed (irrespective of the stimulus or of the task) were recorded especially from motor and post-central cortex, and to a lesser extent in anterior frontal cortex, always just prior to or following the time of the response. Wave forms dependent on the task as determined by the reinforcing contingencies (but independent of the particular stimulus presented or the particular panel pressed) were recorded primarily from the inferior temporal cortex, and rarely from prestriate and anterior frontal cortex. While task-related wave forms began to appear shortly after stimulus presentation, they became especially apparent around the time of the response. This response-linking increased in prominence as the subject achieved 90% proficiency in each task, only to drop off with overtraining. Further, the task-related wave form does not change as rapidly as does overt behavior when the reinforcement contingency is shifted from one stimulus dimension to another. The relevance of these results to an understanding of the process of selective attention is discussed.

Animals↗

PubMed2006

The effects of lateralized training on spontaneous forelimb preference, lesion deficits, and graft-mediated functional recovery after unilateral striatal lesions in rats.

The ability of striatal embryonic grafts to promote functional recovery on complex behavioral tasks depends on various factors, including the amount of striatal-like tissue within the grafts and the duration of post-graft training. However, how the innate paw bias of animals is affected by experience, or influences recovery following injury, is less known. Here, we have examined the effects of intrinsic side bias and lateralized limb use training on spontaneous forelimb preference and graft-mediated functional recovery in a skilled reaching task in a rodent model of Huntington's disease. Naïve rats were assessed on their baseline paw preferences when reaching between the bars of their cage to retrieve sugar pellets from a tray attached outside. Next, rats were lesioned unilaterally in the lateral dorsal striatum with quinolinic acid, and 7-10 days later, half of the animals were given suspension grafts prepared from E15 whole ganglionic eminence implanted into the lesioned striatum. The animals then received extensive unilateral training, either ipsi- or contralateral to the side of the lesion and graft in separate subgroups, on the 'staircase' task until asymptotic performance was obtained. As reported previously, the grafts alleviated lesion-induced deficits in retrieving pellets from the contralateral staircase. Spontaneous biases were then reassessed in the cage-reaching task. Irrespective of whether the animal received ipsilateral or contralateral staircase training, the unilateral lesions induced a significant shift in spontaneous bias towards the ipsilateral paw. Grafted animals showed a similar shift in bias if staircase training was given to the ipsilateral paw but showed no change in spontaneous bias (similar to controls) if they had received contralateral training during the post-transplantation period. The results suggest that striatal grafts can alleviate lesion-induced changes in their spontaneous side preferences, but only if they receive extensive training in the use of the contralateral limb, compatible with the notion that recovery is use-dependent.

Animals↗

PubMed2005

Precise timing accounts for posttraining sleep-dependent enhancements of the auditory mismatch negativity.

Memory consolidation is a long-lasting dynamic process by which new acquired information is transformed at different analysis levels, from molecules to cognition, without additional practice. Results from a previous study on event-related potentials (ERPs) suggest that part of the neural events promoting changes in the electrophysiological correlates of enhanced automatization in a sound discrimination task occur during sleep. These data were reanalyzed in the present study at the single-trial level, and results indicated that the first night of sleep succeeding training is absolutely required to improve the timing consistency of cortical neural assemblies involved in automatic sound-change detection, as revealed by a significant reduction in the latency-jitter of the MMN response across trials. This change in the regularity of the brain response to previously trained sounds facilitated involuntary switch of attention towards the same sounds when they were task irrelevant, as reflected by the P3a emergence after posttraining sleep. Both responses were, however, prevented in subjects deprived of sleep the night following training in the sound discrimination task. We hypothesize that the reduction in the MMN latency-jitter, which, in turn, triggered an automatic shift of attention, might result from a change in synaptic efficacy and/or neural excitability, rather than from changes in firing synchronization and/or size of representation.

Acoustic Stimulation↗

PubMed1996

Cognitive performance in tests sensitive to frontal lobe dysfunction in the elderly depressed.

The paper reports the profile of impairment across a variety of cognitive functions with special emphasis on tests sensitive to frontal lobe dysfunction, in 24 elderly depressed patients during and on recovery from mood disorder, compared with 15 age- and sex-matched controls. Traditional neuropsychological tests and a recently developed battery of computerized tests (CANTAB) were used. Impairments were found in the depressed group compared to controls and to themselves on recovery across all domains examined. The depressed group showed deficits on visuospatial recognition memory, attentional shifting at the extra-dimensional shift stage and in measures of both processing and motor speed without impaired accuracy in a visual search task. Impairments were also found on a planning task with disproportionately increased numbers of moves needed for more difficult problems and evidence of both slowed motor response and increased processing time once the task was commenced. Performance on recovery improved across all tasks. Comparisons were made with the performance of patients suffering from dementia of the Alzheimer type (DAT) and Parkinson's disease on similar tests. Response latencies in test performance were found to correlate with the number of episodes of depression suffered and with ventricular size on CT scan, as measured by computerized planimetry. On recovery, residual depression scores correlated with latency of test performance and with ventricular brain ratio. The results, thus, show that depression in the elderly is associated with a significant degree of deficit on tests sensitive to frontostriatal dysfunction. Some of the deficits appear specific to depression and some do not remit following clinical recovery. However, these impairments have to be interpreted in the context of a broad profile of cognitive deficit.

Aged↗

PubMed2001

An event-related potential evaluation of involuntary attentional shifts in young and older adults.

Involuntary shifts in attention to irrelevant stimuli were studied in elderly and young volunteers during a dichotic-listening task. Event-related potentials and behavioral measures were recorded. Volunteers heard pairs of tones presented with 2 different stimulus onset asynchronies (SOAs). To-be-ignored tones were presented to the left ear, followed by to-be-attended tones to the right ear. Left-ear tones were a frequent standard (700 Hz) and an infrequent small (650 Hz) and large (500 Hz) deviant. Right-ear tones (1500 Hz) were presented with 2 equiprobable intensities. Volunteers responded to the lower intensity stimulus. Behavioral performance was impaired at the short SOA when to-be-ignored large deviants preceded to-be-attended targets, but more so for the elderly volunteers. Large deviants also elicited the mismatch negativity (MMN) and P3a for both age groups. It was concluded that the more impaired behavioral performance observed for the elderly was due to greater sensitivity to output from the MMN system by a frontal lobe system responsible for the maintenance of attentional focus.

Adult↗

PubMed2003

Gaze bias both reflects and influences preference.

Emotions operate along the dimension of approach and aversion, and it is reasonable to assume that orienting behavior is intrinsically linked to emotionally involved processes such as preference decisions. Here we describe a gaze 'cascade effect' that was present when human observers were shown pairs of human faces and instructed to decide which face was more attractive. Their gaze was initially distributed evenly between the two stimuli, but then gradually shifted toward the face that they eventually chose. Gaze bias was significantly weaker in a face shape discrimination task. In a second series of experiments, manipulation of gaze duration, but not exposure duration alone, biased observers' preference decisions. We thus conclude that gaze is actively involved in preference formation. The gaze cascade effect was also present when participants compared abstract, unfamiliar shapes for attractiveness, suggesting that orienting and preference for objects in general are intrinsically linked in a positive feedback loop leading to the conscious choice.

Choice Behavior↗

PubMed2002

Confirmatory factor analysis of the Behavior Rating Inventory of Executive Function (BRIEF) in a clinical sample.

Evidence for the validity of the Behavior Rating Inventory of Executive Function (BRIEF; Gioia, Isquith, Guy, & Kenworthy, 2000) based on internal structure was examined in a sample of children with mixed clinical diagnoses via maximum likelihood confirmatory factor analysis. Four alternative factor models of children's executive function, based on current theories that posit a unidimensional versus fractionated model (Rabbitt, 1997; Shallice & Burgess, 1991), using the revised 9-scale BRIEF configuration that separates two components of the Monitor scale, were examined for model fit. A 3-factor structure best modeled the data when compared directly with 1-, 2-, and 4-factor models. The 3-factor model was defined by a Behavior Regulation factor consisting of the BRIEF Inhibit and Self-Monitor scales, an Emotional Regulation factor consisting of the Emotional Control and Shift scales, and a Metacognition factor composed of the Working Memory, Initiate, Plan/Organize, Organization of Materials, and Task-Monitor scales. The findings support a fractionated, multi-component view of executive function as measured by the BRIEF.

Adolescent↗

PubMed1994

Musculoskeletal disorders in hospital nurses: a comparison between two hospitals.

Nursing staff members of a urban general hospital (GH) and a small oncological department (OD) were surveyed to determine the prevalence of occupational related musculoskeletal disorders (MSDs), the specific disabilities, accidents at work, and working time lost. All subjects had a medical examination to evaluate osteoarthicular disease and selected cases were invited to X-ray examinations. The purpose of this study was to compare MSDs in the two groups of nurses working in two hospitals with different work organization in the same geographical area, Pordenone in Italy. In the previous year 48% GH and 33% OD nurses reported back pain due to work, 29.4 and 16.1% respectively have had X-ray or orthopaedic examinations, 19.2% and 9.1% had been away from work because of back pain. All these differences are statistically significant. The analysis of musculoskeletal pain sites and working tasks in the two hospital workers shows no differences in distribution. Great difference exists when analysing the numbers of patients assisted by a nurse: 0.57 and 1.27 nurse/patients respectively in GH and OD. Our data indicate a high overall frequency of occupational back pain, similar to other studies in Europe. The comparison between the two hospitals suggests factors associated with the disorder: work tasks and particularly nurses/patients ratio are more important factors than age and length of exposure. Different work distribution, shift organization, a better ratio between nurses and patients, an improvement of equipment provision, and specific nurse-training with application of ergonomic methods could improve work efficiency radically and decrease injury rates.

Adult↗

PubMed2006

Investigation of age-related cognitive decline using mice as a model system: behavioral correlates.

OBJECTIVE: With recent advances in molecular genetics, mouse models have been generated for a number of disease states. Recently, the authors and others have begun to examine normal age-related cognitive decline using mice as a model system. In this article, and the companion article that follows, the authors present data intended to better parameterize the aging phenotype in mice and examine the possible underlying neuronal mechanisms with special emphasis on age-related changes in calcium homeostasis. METHODS: Young (4-6-month-old) and aged (22-24-month-old) C57BL/6 mice were analyzed in terms of their spatial learning abilities in the hidden platform version of the Morris water maze and the delay win-shift version of the Olton radial arm maze. RESULTS: Although aged mice exhibited cognitive impairments in both behavioral tasks used, the extent of impairment differed between the two tasks, which might prove to be advantageous under certain experimental settings. CONCLUSIONS: Like in other areas of biomedical research, mice have become an invaluable research tool in the investigation of learning and memory. It is expected that similar benefits can be realized by developing mouse models for age-related cognitive decline.

Aging↗

PubMed1991

Deviate N200 component of event-related potentials in shuchaku-seikaku, a premorbid personality of depression.

Twenty-one healthy subjects with Shuchaku-Seikaku (SS), a premorbid personality of depression, and 44 control subjects were tested for event-related potentials using the auditory odd ball paradigm. A higher percent of the N200 component was evoked by frequent task-irrelevant stimuli in the Shuchaku-Seikaku (81.0%) subjects than in the controls (45.5%). The mean amplitudes in the 50-100 ms latency range for task-relevant rare stimuli were smaller; whereas, the amplitudes in the 100-200 ms range for task-irrelevant frequent stimuli and the amplitudes in the 200-260 ms range for both stimuli were larger (shifted to negative direction) in the SS subjects than in the controls. The evidence suggests that the fully automatic detection process, which is assumed to be correlated with mismatch negativity, is hypoactivated and that a contrarily controlled or conscious mismatch process, which may be N2b, is hyperactivated in SS.

Adolescent↗

PubMed1962

Transfer effects of successive discrimination-reversal training in chimpanzees.

Chimpanzees receiving successive discrimination-reversal training on a single pair of stimuli transferred almost perfectly to two additional reversal tasks and to a "learning-set" series of 180 discrimination problems. A "win-stay, lose-shift" strategy, however it is acquired, seems to be a sufficient basis for one-trial discrimination learning.

Animals↗

PubMed1999

Activation of distinct motor cortex regions during ipsilateral and contralateral finger movements.

Previous studies have shown that unilateral finger movements are normally accompanied by a small activation in ipsilateral motor cortex. The magnitude of this activation has been shown to be altered in a number of conditions, particularly in association with stroke recovery. The site of this activation, however, has received limited attention. To address this question, functional magnetic resonance imaging (MRI) was used to study precentral gyrus activation in six control and three stroke patients during right index finger tapping, then during left index finger tapping. In each hemisphere, the most significantly activated site (P < 0.001 required) was identified during ipsilateral and during contralateral finger tapping. In the motor cortex of each hemisphere, the site activated during use of the ipsilateral hand differed from that found during use of the contralateral hand. Among the 11 control hemispheres showing significant activation during both motor tasks, the site for ipsilateral hand representation (relative to contralateral hand site in the same hemisphere) was significantly shifted ventrally in all 11 hemispheres (mean, 11 mm), laterally in 10/11 hemispheres (mean, 12 mm), and anteriorly in 8/11 hemispheres (mean, 10 mm). In 6 of 11 hemispheres, tapping of the contralateral finger simultaneously activated both the ipsilateral and the contralateral finger sites, suggesting bilateral motor control by the ipsilateral finger site. The sites activated during ipsilateral and contralateral hand movement showed similar differences in the unaffected hemisphere of stroke patients. The region of motor cortex activated during ipsilateral hand movements is spatially distinct from that identified during contralateral hand movements.

Brain Mapping↗

PubMed2000

Local infusion of scopolamine into intraparietal cortex slows covert orienting in rhesus monkeys.

There is accumulating evidence to suggest that cholinergic neurotransmission may play an important role in visuospatial attention, but the brain sites at which acetylcholine modulates attention are not well understood. The present work tested the hypothesis that the cholinergic influences within the intraparietal cortex are necessary for normal attentional shifting (covert orienting) in nonhuman primates. Two rhesus monkeys were trained to perform a visual, cued target detection task for liquid reinforcement. The animals pressed a lever to produce a visual display in which a central fixation point was flanked by two circles. Shortly after fixation was established, one of the circles brightened (cue), and a target appeared subsequently within one of the circles. Detection was signaled by a manual response and the reaction time to the appearance of the target was recorded. Four types of trials were presented. For valid cue trials, the cue and target were at the same spatial location; for invalid cues, cue and target were in opposite hemifields; for double cues, both cues were brightened but the target appeared in either the left or right circle; in no-cue trials, the cue was omitted. We localized the intraparietal region by recording attention-related, cellular activity with intracerebral microelectrodes. Among visually responsive cells in this area, valid cues presented to the receptive fields of visual neurons enhanced the responses to target stimuli in about half the cells and inhibited those responses in the remainder. In addition, some cells showed longer response latencies to invalid cues than to valid cues. We then infused scopolamine into attention-related activity sites and assessed its effect on performance. Scopolamine produced a dose-dependent increase in reaction times and decrease in performance accuracy that lasted more than 1 h. Neither vehicle injections in the same locations nor scopolamine outside the physiologically defined area produced any significant change in behavior. Under our conditions of measurement, we conclude that activity mediated by muscarinic cholinergic receptors within the intraparietal cortex is necessary for normal covert orienting.

Animals↗

PubMed2006

On framing effects in decision making: linking lateral versus medial orbitofrontal cortex activation to choice outcome processing.

Two correlates of outcome processing in the orbitofrontal cortex (OFC) have been proposed in the literature: One hypothesis suggests that the lateral/medial division relates to representation of outcome valence (negative vs. positive), and the other suggests that the medial OFC maintains steady stimulus-outcome associations, whereas the lateral OFC represents changing (unsteady) outcomes to prepare for response shifts. These two hypotheses were contrasted by comparing the original with the inverted version of the Iowa Gambling Task in an event-related functional magnetic resonance imaging experiment. Results showed (1) that (caudo) lateral OFC was indeed sensitive to the steadiness of the outcomes and not merely to outcome valence and (2) that the original and the inverted tasks, although both designed to measure sensitivity for future outcomes, were not equivalent as they enacted different behaviors and brain activation patterns. Results are interpreted in terms of Kahneman and Tversky's prospect theory suggesting that cognitions and decisions are biased differentially when probabilistic future rewards are weighed against consistent punishments relative to the opposite scenario [Kahneman, D., & Tversky, A. Choices, values, and frames. American Psychologist, 39, 341-350, 1984]. Specialized processing of unsteady rewards (involving caudolateral OFC) may have developed during evolution in support of goal-related thinking, prospective planning, and problem solving.

Adult↗

PubMed2004

Linking better shiftwork arrangements with safety and health management systems.

OBJECTIVE: Various support measures useful for promoting joint change approaches to the improvement of both shiftworking arrangements and safety and health management systems were reviewed. A particular focus was placed on enterprise-level risk reduction measures linking working hours and management systems. METHODS: Voluntary industry-based guidelines on night and shift work for department stores and the chemical, automobile and electrical equipment industries were examined. Survey results that had led to the compilation of practicable measures to be included in these guidelines were also examined. The common support measures were then compared with ergonomic checkpoints for plant maintenance work involving irregular nightshifts. On the basis of this analysis, a new night and shift work checklist was designed. RESULTS: Both the guidelines and the plant maintenance work checkpoints were found to commonly cover multiple issues including work schedules and various job-related risks. This close link between shiftwork arrangements and risk management was important as shiftworkers in these industries considered teamwork and welfare services to be essential for managing risks associated with night and shift work. Four areas found suitable for participatory improvement by managers and workers were work schedules, ergonomic work tasks, work environment and training. The checklist designed to facilitate participatory change processes covered all these areas. CONCLUSIONS: The checklist developed to describe feasible workplace actions was suitable for integration with comprehensive safety and health management systems and offered valuable opportunities for improving working time arrangements and job content together.

Circadian Rhythm↗

PubMed1995

Expectancy for change and adaptation to a new signal probability.

An experiment showed that the higher the 18 observers' expectancy for change in signal probability (without knowing the future probability), the more successful the adaptation to a new probabilistic environment in terms of shift in response criterion.

Adaptation, Psychological↗