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Results for “Task Shifting”

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PubMed1981

Invariant characteristics of partial masking: implications for mathematical models.

The loudness of a tone in a noisy background increases very rapidly above its threshold with increasing intensity of the tone. The particular curve describing loudness growth as measured by a loudness matching paradigm depends on the level of the background noise. We introduce the hypothesis that an increment in masking noise induces a shift of the loudness matching curve in a diagonal direction (the matching curve being plotted in conventional log--log coordinates). This shift invariance is shown here to hold empirically for individual subjects within a monaural loudness matching task, based on a 2IFC paradigm using 1000-Hz tones and a wide band Gaussian noise. Shift invariance places considerable restrictions on models feasible for such data. In conjunction with a very general class of models involving the notion of gain control, the shift invariance property determines all parametric forms possible for the loudness matching functions. The fit of such parametric expressions to the data reported here yields very satisfying results. The resulting model is also found to be consistent with relevant results in the literature.

Humans↗

PubMedDate not supplied

Dementia accompanying motor neuron disease.

This study presents a structural and clinical description of a patient with dementia of motor neuron disease (D-MND), and compares and contrasts the neuropsychological characteristics of this patient with those of a group of patients with Alzheimer's disease (AD) matched by severity of dementia. The D-MND patient as well as the AD patients performed abnormally on all tasks that assessed executive/frontal functions. However, the D-MND patient tended to be more impaired than AD patients on tasks that required high speed decisions and on shifting from one strategy to another. Deficits in memory, language, and lexical-semantic abilities were also apparent in this patient. The co-occurrence of signs and symptoms characteristics of 'subcortical' dementia with those of 'cortical' dementia suggest that the executive system dysfunction may be secondary to subcortical pathology.

Alzheimer Disease↗

PubMed1999

Lateralization of cerebral blood flow velocity changes during cognitive tasks. A simultaneous bilateral transcranial Doppler study.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasonography (TCD) permits the assessment of cognitively induced cerebral blood flow velocity (BFV) changes. We sought to investigate the lateralization of BFV acceleration induced by a variety of cognitive tasks and to determine the influence of age, gender, IQ, and quality of the performance on the relative BFV changes. METHODS: Simultaneous bilateral TCD monitoring of BFV in the middle cerebral arteries (MCAs) was performed in 90 normal right-handed volunteers during 13 verbal and visuospatial tasks and their preceding rest periods. RESULTS: All tasks induced a significant bilateral BFV increase in the MCAs compared with the preceding rest periods. Five verbal tasks showed a significant left-hemispheric BFV acceleration. Linguistic tasks that required active or creative processing of the verbal stimuli, such as sentence construction or word fluency, elicited the most asymmetric response. Five visuospatial tasks revealed a significant right-hemispheric BFV shift. Paradigms that combined visuospatial attention and visuomotor manipulation showed the most lateralized acceleration. Older volunteers (aged >50 years) showed higher relative BFV changes, but lateralization was not influenced by age. Gender, IQ, and performance quality did not reveal significant effects on BFV change. CONCLUSIONS: Bilateral TCD is a noninvasive technique that has the potential to connect the particular change in flow pattern of the MCA distribution with selective cognitive activity and thus offers specific functional information of scientific and clinical value.

Adolescent↗

PubMed1998

Mutual regression: altered states in the psychoanalytic situation.

Regression is one of the most controversial topics in the psychoanalytic literature, and disagreements continue regarding a number of propositions central to the issue. On the one hand are those who maintain a traditional view that analysis facilitates regression, through both its setting and its method. On the other are critics from diverse theoretical schools, Freudian, Kleinian, and interpersonal, who have argued that the setting does not, and that the analyst should not, induce or encourage regression. This paper reexamines the fundamentals of regression and relates the concept to the notion of altered states of consciousness. From a relational position, it is argued that patient and analyst mutually regulate regressive states in each other, and that this is an important aspect of the analytic process. One of the analyst's roles is to facilitate the patient's shift into the state best suited for the task of the moment and, often, to improve the patient's ability to internally and interpersonally regulate and move between various states of consciousness. The analyst's commitment to state control as a mutual endeavor helps safeguard the patient's autonomy.

Awareness↗

PubMed1995

Promoting strategic learning by postsecondary students with learning disabilities.

The research described here investigated the effectiveness of an intervention model designed to promote self-regulated and strategic learning: Strategic Content Learning (SCL). In SCL, rather that focusing on teaching students specific cognitive strategies, instruction focuses on supporting students to develop a strategic approach to learning. The study comprised six parallel case studies embedded within a single-group, pre-post design. Each student chose a task of importance to current or future academic work, and individualized support was provided on those tasks. Participants were adults with learning disabilities (5 women and 1 man, ages 18 to 36 years) enrolled in postsecondary education programs. Results indicated, that students' task performance improved. Additionally, gains in metacognitive knowledge about tasks and strategies, increased perceptions of self-efficacy, and shifts in attributional patterns were observed. Most critically, the evidence suggested that students became more self-regulated in their learning: They were active in developing and modifying strategies, they transferred strategies across contexts, and they began to attack noninstructed tasks strategically. The particular suitability of SCL as an intervention for adults with learning disabilities is described, and implications of the findings for research and practice are discussed.

Adolescent↗

PubMed1986

Biofeedback of visual evoked potentials.

The present study investigated the operant conditioning of visual evoked potentials within a latency range between 200 and 600 ms using a visual discrimination task, and scrutinized whether biofeedback-induced potential shifts covaried with behavioral responses (reaction time, RT). It could be demonstrated that subjects were able to modify their ERPs towards more or less positivity according to the instruction given. In addition, in could be shown that a biofeedback-induced greater positivity of the P300-complex was highly correlated with a decrease of reaction time. It is hypothesized that this could be due to a modification of P300-components reflecting information processing.

Adult↗

PubMed2005

Attention capture is modulated in dual-task situations.

Because some features affect the efficiency of visual search even when they are irrelevant to the task, they are thought to capture attention in a stimulus-driven manner. If such attention shifts are stimulus driven, they should be unaffected by reduced resources. We added a concurrent auditory task to a traditional attention capture paradigm and found that capture by an irrelevant, abruptly appearing stimulus (i.e., an onset) was eliminated. In contrast, prioritization of an irrelevant color singleton--a stimulus that at most receives only mild prioritization in this paradigm--was increased under dual-task conditions. These results challenge the hypothesis that attention capture by irrelevant features is stimulus driven. Instead, prioritization depends on and is modulated by the availability of resources.

Attention↗

PubMed1975

Jamestown Medical Clinic System.

Comprehensive health care can be provided in rural and poor areas despite a decreasing number of physicians in those areas. A single physician increased his productivity by 300% to 400% by combining already available resources: specially trained and supervised nurse-practitioners, problem-oriented charting, and multiphasic screening. With emphasis on the nurse-practitioner as the main "person of contact" for the patient, the physician is able to shift from 50% to 75% of his usual tasks to these specially trained personnel. Patients have come to regard the physician as a "consultant" to the nurse-practitioner.

Community Health Services↗

PubMedDate not supplied

[Electrophysiology of executive functions].

INTRODUCTION: In neuropsychology, executive functions have been defined as those that coordinate the flow of information processing in the brain. In the last decade its study has undergone an important development, partly due to the use of functional neuroimaging. DEVELOPMENT: Electrophysiological techniques have also provided a link between two specific components of the event related brain potential (ERP) and certain control and monitoring processes, as those described in theoretical frameworks of executive functioning (i.e., Norman & Shallice). On the one hand, attentional set shifting paradigms allow us to relate the anteriorly (P3a; latency 300-350 ms) and posteriorly (P3b; latency 450-600 ms) distributed components of the so called 'novelty P3', with a more general mechanism of attentional set shifting that could account for both stimulus and task novelty. On the other hand, 'error related negativity' (ERN or En) has shown its sensitivity to action monitoring (i.e., error detection and error correction processes), during the execution of response selection RT tasks. CONCLUSIONS: The comprehension of these two executive processes represents critical aspects in our understanding of brain function, and has direct applications to the design of both theoretical models and assessment and rehabilitation programs for patients with dysexecutive disorders.

Cognition↗

PubMedDate not supplied

[Analysis of arterial hypertension and work in the epidemiologic study "Aging, Health and Work"].

OBJECTIVE: We evaluated if work conditions or job strain related to professional activity or to life styles represent a risk factor for arterial hypertension and whether this effect of hypertension is independent of age. DESIGN: through data collection of epidemiological inquiries ESTEV and VISAT, applied in Italy on a cohort of workers, 32-52 year-old, employed in different productive sectors, we analyzed the relationships on working conditions (exposure to certain risks or job strain), life styles and self evaluation of health and arterial hypertension. Hypertension was considered as SAP > or =160 mm/Hg and/or DAP > or =90 mm/Hg, or current antihypertensive treatment. RESULTS: the results refer to 1104 workers, 76% men and 24% women. Prevalence of hypertension was found to be higher among the men than women (33% vs. 22%). Risk estimation in multivariate analysis, by logistic regression model, showed a statistically significant association with certain work-related factors such as: shift work, awkward posture, standing work, doing several tasks contemporarily, being interrupted at work, not being able to take eyes off work. The variables referred to cognitive aspects and work organization tended to be associated to arterial hypertension even when exposure ceased. CONCLUSIONS: both physical and cognitive organisational aspects of work are strongly associated with arterial hypertension. The subjective assessment that workers give to their work is a relevant element. This aspects should be considered as a possible reducible risk factor.

Adult↗

PubMed1995

The priority of separable perception in stimulus classifications of children with mental retardation.

Children (mean CA = 12 years) with mental retardation and adults without mental retardation classified tetrads of stimuli that could be grouped according to identities on separate dimensions or according to overall similarity. When color, size, and line orientation were varied (Experiment 1), both groups used separate dimensions for classification. When hue, saturation, and brightness varied (Experiment 2), both groups used overall similarity for classification. Test-retest correlations showed that the predominant classifications were reliable across 1-week testing intervals. Results support Garner's distinction between separable and integral stimulus structure but do not support an integral-to-separable shift in perceptual development. Comparisons of the tetrad task used in the present study and triads used in previous work are discussed as well as implications of the present data for developmental theories of perceptual classification and processing in children with mental retardation.

Adolescent↗

PubMed2003

Regional brain activation associated with different performance patterns during learning of a complex motor skill.

In understanding the brain's response to extensive practice and development of high-level, expert skill, a key question is whether the same brain structures remain involved throughout the different stages of learning and a form of adaptation occurs, or a new functional circuit is formed with some structures dropping off and others joining. After training subjects on a set of complex motor tasks (tying knots), we utilized fMRI to observe that in subjects who learned the task well new regional activity emerged in posterior medial structures, i.e. the posterior cingulate gyrus. Activation associated with weak learning of the knots involved areas that mediate visual spatial computations. Brain activity associated with no substantive learning indicated involvement of areas dedicated to the declarative aspects learning such as the anterior cingulate and prefrontal cortex. The new activation for the pattern of strong learning has alternate interpretations involving either retrieval during episodic memory or a shift toward non-executive cognitive control of the task. While these interpretations are not resolved, the study makes clear that single time-point images of motor skill can be misleading because the brain structures that implement action can change following practice.

Adult↗

PubMed1999

An investigation of attention allocation during sequential eye movement tasks.

Allocation of visuo-spatial attention during dynamic viewing was investigated with a dual task. Primary tasks (reading, scanning, searching) all required sequential left-to-right eye movements. An additional speeded manual response was made to a visual probe that appeared early or late after the onset of a randomly determined fixation (25 or 170 msec probe delay). The probe appeared to the left, directly above, or to the right of the currently fixated character (-10, -5, 0, +5, or +10 characters probe eccentricity). Faster probe detection near the location of the forthcoming eye fixation was found in the search task, but not during reading or scanning. Fixation times increased and saccade lengths decreased as a consequence of probing in all three tasks. Fixations were, however, less prolonged when the probe appeared in the right than when it appeared in the left hemifield, and saccades were greatest when the probe appeared at +10 characters. The results extend the notion of goal-directed attention shifts to free viewing and highlight the impact of task-specific processing requirements.

Adolescent↗

PubMed2004

Relationship of behavioural and symptomatic syndromes in schizophrenia to spatial working memory and attentional set-shifting ability.

BACKGROUND: Behavioural syndromes (thought disturbance, social withdrawal, depressed behaviour and antisocial behaviour) offer a different perspective from that of symptomatic syndromes on the disability that may be associated with schizophrenia. Few studies have assessed their relationship with neuropsychological deficits. We hypothesized that these syndromes may represent behavioural manifestations of frontal-subcortical impairments, previously described in schizophrenia. METHOD: Long-stay inpatients (n=54) and community patients (n=43) with enduring schizophrenia were assessed, using measures of symptoms and behaviour and tests of executive functioning. The relationship between syndromes and neuropsychological function was assessed using multiple regression and logistic regression analyses. RESULTS: Significant associations were found between performance on the spatial working memory task and the psychomotor poverty symptomatic syndrome, and between attentional set-shifting ability and both disorganization symptoms and the thought disturbance behavioural syndrome. These results were not explained by the effect of premorbid IQ, geographical location, length of illness or antipsychotic medication. Length of illness was an independent predictor of attentional set-shifting ability but not of working memory performance. CONCLUSION: The specific relationship between negative symptoms and spatial working memory is consistent with involvement of the dorsolateral prefrontal cortex. The associations between difficulty with set-shifting ability and both disorganization symptoms and behaviours may reflect inability to generalize a rule that had been learned and impaired ability to respond flexibly. The specific relationship of illness duration to set-shifting ability may suggest progressive impairment on some executive tasks. The nature of these relationships and their neurobiological and rehabilitation implications are considered.

Adult↗

PubMed1999

Transient neural activity in the medial superior frontal gyrus and precuneus time locked with attention shift between object features.

To investigate the contribution of the superior frontal gyrus and precuneus to the cognitive process of attention set shift, we examined the correlation between change in neural activity in these areas and the timing of attention set shift using event-related functional magnetic resonance imaging. Seven subjects underwent a card-sorting task in which they matched a test card to one of two target cards according to color or shape. The subjects had to determine the correct category based only on feedback and shift the sorting principle when the feedback changed from "correct" to "incorrect." Transient increase of neural activity time locked with attention shift phases was detected in the medial superior frontal gyrus (the rostral part of the supplementary motor area) and precuneus. During the control task, in which the feedback and the motor responses were preserved without any attention shift, this type of change in neural activity was not observed. Our findings indicate that increase in neural activity in these brain areas may be closely related to attention set shift between object features and suggest that these areas may play a role in the shifting of cognitive sets.

Adult↗

PubMed2005

Supervised learning of postural tasks in patients with poststroke hemiparesis, Parkinson's disease or cerebellar ataxia.

Supervised learning of different postural tasks in patients with lesions of the motor cortex or pyramidal system (poststroke hemiparesis: 20 patients), nigro-striatal system (Parkinson's disease: 33 patients) and cerebellum (spinocerebellar ataxia: 37 patients) was studied. A control group consisted of 13 healthy subjects. The subjects stood on a force platform and were trained to change the position of the center of pressure (CP) presented as a cursor on a monitor screen in front of the patient. Subjects were instructed to align the CP with the target and then move the target by shifting the CP in the indicated direction. Two different tasks were used. In "Balls", the target (a ball) position varied randomly, so the subject learned a general strategy of voluntary CP control. In "Bricks", the subject had to always move the target in a single direction (downward) from the top to the bottom of the screen, so that a precise postural coordination had to be learned. The training consisted of 10 sessions for each task. The number of correctly performed trials for a session (2 min for each task) was scored. The voluntary control of the CP position was initially impaired in all groups of patients in both tasks. In "Balls", there were no differences between the groups of the patients on the first day. The learning course was somewhat better in hemiparetic patients than in the other groups. In "Bricks", the initial deficit was greater in the groups of parkinsonian and cerebellar patients than in hemiparetic patients. However, learning was more efficient in parkinsonian than in hemiparetic and cerebellar patients. After 10 days of training, the hemiparetic and cerebellar patients completed the acquisition at a certain level whereas the parkinsonian patients showed the ability for further improvement. The results suggest that motor cortex, cerebellum, and basal ganglia are involved in voluntary control of posture and learning different postural tasks. However, these structures play different roles in postural control and learning: basal ganglia are mainly involved in learning a general strategy of CP control while the function of the motor cortex chiefly concerns learning a specific CP trajectory. The cerebellum is involved in both kinds of learning.

Adult↗

PubMed1992

Aging and shifts of visual spatial attention.

Three experiments examined adult age differences in the efficiency of endogenous (voluntary) and exogenous (involuntary) attention shifts. Younger and older subjects performed a spatial cuing task in which abruptly onset peripheral cues (Experiment 1) or central, symbolic cues (Experiments 2 and 3) were presented before a target stimulus at intervals ranging from 50 to 250 ms. With peripheral cues, the magnitude of cuing effects was at least as great for older as for younger adults and followed a similar time course. Similar results were obtained with symbolic cues, although cuing effects for older adults varied with cue difficulty. The results suggest that cue encoding may decline with advancing age but that the efficiency of the shift process is preserved.

Adolescent↗

PubMed1987

Cognitive task influence on relative hemispheric motor control: mouth asymmetry and lateral eye movements.

While strictly verbal cognitive tasks showed a strong left-hemisphere dominance, the presence of visualization and emotion in cognitive tasks resulted in increased involvement of the right hemisphere in motor control of speech as measured by mouth asymmetry. Spontaneous smiles showed right-hemisphere dominance. Lateral eye movements showed an unexpected shift to left gaze during speech which may suggest a dual task interference between speech and gaze motor control.

Adolescent↗