Biomedical subjects

Paul A T M Eling

Publications and source records attributed to Paul A T M Eling.

9 recordsLinked to original sources

PubMed2005

Mental and physical effort affect vigilance differently.

Both physical and mental effort are thought to affect vigilance. Mental effort is known for its vigilance declining effects, but the effects of physical effort are less clear. This study investigated whether these two forms of effort affect the EEG and subjective alertness differently. Participants performed a physical task and were subsequently presented with a mental task, or vice versa. Mental effort decreased subjective alertness and increased theta power in the EEG. Both results suggest a vigilance decline. Physical effort, however, increased subjective alertness and alpha and beta1 power in the EEG. These findings point towards an increase in vigilance. Beta2 power was reduced after physical effort, which may reflect a decrease in active cognitive processing. No transfer effects were found between the effort conditions, suggesting that the effects of mental and physical effort are distinct. It is concluded that mental effort decreases vigilance, whereas physical effort increases vigilance without improving subsequent task performance.

Adult↗

PubMed2005

Depressive symptom quality and neuropsychological performance in dementia.

BACKGROUND: It is unknown to what extent depression and cognitive dysfunction are related in subjects with dementia. A limitation of earlier studies is that only general measures of depression have been studied. METHODS: In a sample of 60 subjects with dementia according to DSM-III-R criteria depressive symptoms were divided into factors of mood and motivation disturbance according to a principal components analysis. Correlations were computed between the factor scores and the performance on a number of specific neuropsychological tests. As the symptom content of motivation disturbance suggests subcorticofrontal dysfunction it was hypothesized that this factor is related to impaired executive functions. RESULTS: 77% of the depressive symptoms contributed to the dimension of motivation disturbance and most of these symptoms occurred outside the context of a major depressive episode. Our hypothesis was supported by a significant negative correlation between motivation symptoms and semantic verbal fluency. This relationship seems to have specificity, as both the dimensions of mood symptoms and of general depressive symptoms did not correlate significantly with specific neuropsychological test scores. CONCLUSIONS: The division of depressive symptoms in factors of mood and motivation disturbance contributes to insight into the relationship between depression and cognitive dysfunction in dementia. An advantage of the motivation disturbance factor compared to the regular apathy scales is that it consists of depressive symptoms. Therefore, it becomes evident that apathy or impaired motivation may occur in patients with dementia both in and outside the context of a depressive syndrome.

Affective Symptoms↗

PubMed2005

Diurnal spectral EEG fluctuations in narcoleptic patients during rest and reaction time tasks.

Narcolepsy is associated with lowered vigilance. Diurnal variation in vigilance appears altered, but the exact nature of this change is unclear. It was hypothesized that the homeostatic sleep drive is increased in narcolepsy. Decreased levels of vigilance are reflected in low frequency band power in the electroencephalogram (EEG), so these frequencies were expected to be increased in the narcolepsy group. Furthermore, it was expected that low frequency power should increase over the day. Narcoleptic patients and healthy controls participated (36 participants in total); they were not allowed to take medication or naps on the experimental day. EEG was measured at 9:00, 11:00, 13:00, 15:00, and 17:00 hours, during rest and during reaction time tasks. In the narcolepsy group, alpha power was lower at rest at all times. Delta and theta power during rest and task performance increased steadily over the day in this group, from 11:00 hours onwards. Additionally, in the narcolepsy group beta1 and beta2 power during rest appeared increased at the end of the day. The effects in the lower frequency bands strongly suggest that vigilance is low at all times. The progressive increase in low frequency power indicates that the sleep drive is enhanced. It is not clear whether this pattern reflects an extreme state of low vigilance, or a pathological brain condition. The effects in the higher frequencies suggest that narcoleptic patients may make an effort to counteract their low vigilance level.

Adult↗

PubMed2004

Mental effort causes vigilance decrease due to resource depletion.

The resource view on vigilance performance was tested. First, a low demanding task was compared with a similar low demanding task in which stimulus presentation was less monotonous due to added, irrelevant, stimuli. The resource view, maintaining that vigilance is lowered by hard mental work, predicts that addition of irrelevant stimuli will not affect performance. The classic arousal theory, however, states that arousal drops due to monotonous stimulus presentation and predicts that decreasing monotony will enhance performance. Results showed that performance was unaffected by added stimuli. Second, we tested whether a high-demanding task (with identical stimulus presentation as the low demanding task, but different instruction) would cause a greater decline in performance than the low demanding task. Indeed, in the high-demanding task performance was affected most. In sum, it appears that vigilance decreases due to hard mental work, which requires many resources. Both overall performance and decrement in performance can be explained in terms of resources, and this suggests that vigilance tasks should be resource-demanding tasks, which do not have to be of long duration.

Adult↗

PubMed2004

Mental effort affects vigilance enduringly: after-effects in EEG and behavior.

Vigilance is assumed to decline with sustained task performance. The EEG-effects during performance on mental tasks, however, cannot be ascribed indisputably to vigilance decline per se. During task performance itself, effects of information processing and vigilance decline may be confounded. In this study, effects of sustained mental effort were studied in the absence of specific information processing, after sustained information processing had taken place, namely after an effortful 70-min intelligence test. Vigilance was determined by means of EEG-measures in a rest condition. Furthermore, behavioral performance was assessed on two different tasks, the traditional Clock test and the SART. After mental effort, theta power in the EEG and errors on the SART were increased. Beta2 power, however, also appeared enhanced. We conclude that sustained mental effort produces an enduring decrease in vigilance, but that some active processing is enhanced at the same time. A second study replicated the EEG-results after mental effort.

Adult↗

PubMed2004

Decreased movement speed in girls with turner syndrome: a problem in motor planning or muscle initiation?

In three experiments with graphical tasks we examined whether the decreased movement speed in girls with Turner Syndrome (TS) is caused either by a diminished planning capacity or by more peripheral motor execution problems. Fourteen girls with TS and 14 matched controls (mean age 11.6 years) participated. Task difficulty addressed the muscle-initiation, size control, and shape-programming level (Van Galen, 1991). The influence of task difficulty on accuracy, velocity, velocity profile and dwell time was analyzed and confirmed that girls with TS do not plan and program their movements differently from normals. We conclude that the decreased movement speed in TS is caused by problems at the muscle initiation level.

Analysis of Variance↗

PubMed2003

A review of neuropsychological and motor studies in Turner Syndrome.

We reviewed the literature on Turner Syndrome (TS) from 1962 until March 2003 with respect to the following questions: Is there a consistent pattern of cognitive and/or motor dysfunction in TS girls and if so, is there an explanation for the disturbance? Many studies indicate that girls with TS have a disharmonic IQ profile: a verbal IQ that seems to be at a (nearly) normal level and a decreased PIQ. This profile remains into adulthood. Visual-spatial problems are mentioned most frequently and there is some evidence for a relationship to particular neuro-anatomical structures, hormonal dysfunction, and genotype. Although much less research has been done on motor performance in TS, there is clear evidence that it is disturbed too in TS. Many authors emphasize the interaction between somatic, psychological and social factors, but we did not find a clear theoretical framework explaining this relationship. We argue that there may be two independent problems: a visuospatial and a motor deficit possible related to specific genotypes and both have implications for functioning in daily life.

Cerebral Cortex↗

PubMed2003

Slow motor performance in girls with Turner Syndrome is not related to increased neuromotor noise.

This study examined the relationship between decreased speed-accuracy trade-off and increased neuromotor noise in girls with Turner Syndrome (TS). Fifteen girls with TS and 15 age-matched controls performed isometric force contractions with both index fingers separately at 5 force levels, based on their maximum voluntary contraction. The results revealed that (a) groups did not differ in speed-accuracy tradeoff or neuromotor noise, (b) output-variability increased linearly with force level, (c) signal-to-noise ratio changed according to an inverted U-shaped function, (d) broadening in the frequency profile is highest at the lower force levels, (e) with increasing force level, the power peak in the 0-4 Hz domain dominates, (f) frequency profile broadens more in the dominant hand. These findings suggest that, in girls with TS, motor performance is not diminished in an isometric force task, that motor recruitment is intact, and that neuromotor noise is not increased. The findings are discussed with respect to motor control and neuromotor noise.

Child↗

PubMed2002

Low elementary movement speed is associated with poor motor skill in Turner's syndrome.

The article aims to discriminate between 2 features that in principle both may be characteristic of the frequently observed poor motor performance in girls with Turner's syndrome (TS). On the one hand, a reduced movement speed that is independent of variations in spatial accuracy demands and therefore suggests a problem in motor execution. On the other hand, a disproportional slowing down of movement speed under spatial-accuracy demands, indicating a more central problem in motor programming. To assess their motor performance problems, 15 girls with TS (age 9.6-13.0 years) and 14 female controls (age 9.1-13.0 years) were tested using the Movement Assessment Battery for Children (MABC). In additionally, an experimental procedure using a variant of Fitts' graphic aiming task was used to try and disentangle the role of spatial-accuracy demands in different motor task conditions. The results of the MABC reestablish that overall motor performance in girls with TS is poor. The data from the Fitts' task reveal that TS girls move with the same accuracy as their normal peers but show a significantly lower speed independent of task difficulty. We conclude that a problem in motor execution is the main factor determining performance differences between girls with TS and controls.

Analysis of Variance↗