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PubMed2006

Visual area V5/MT remembers "what" but not "where".

Priming for motion direction has been shown to depend upon the functional integrity of extrastriate area V5/MT. Its retinotopic organization and the interactions recently found between motion adaptation and misperceived localization may suggest, for this area, a role for priming of spatial position in addition to the established priming of motion direction. Disruption of V5/MT with repetitive transcranial magnetic stimulation during the intertrial interval had the effect of abolishing priming of motion direction but no effect in priming of spatial position. These effects cannot be explained in terms of perception or task demands but only in terms of the effects of information irrelevant to the correct performance of the task stored over the intertrial interval. We suggest that the attribute of spatial position might be stored in short-term memory either in earlier areas of the motion pathways such as V3 or in higher cortical areas traditionally associated with the analysis of spatial information, for example, posterior parietal cortex or the frontal eye fields.

Adult↗

PubMedDate not supplied

Event-related potential and EEG measures in Parkinson's disease without and with dementia.

Nondemented Parkinson's disease (PD) patients showed increased amplitude of event-related potential component P3. We recorded 18-channel spontaneous eyes-closed resting EEG and auditory oddball event-related potentials in 29 PD patients and 11 age-matched controls. Combining Mini-Mental State Examination score and oddball P3 counting performance, 15 patients were intellectually normal, 7 moderately, and 7 severely demented. P3 and N1 amplitude and latency, mean amplitude of 1,024 ms post-stimulus (separate after rare and after frequent stimuli), and resting EEG total power for 40 s were computed, and linearly regressed for age, sex, and L-dopa dosage. In nondemented PD patients, increased P3 amplitude was confirmed, but N1 amplitude and mean amplitude after rare and frequent stimuli were also increased as well as - most important - resting EEG total power. With increasing dementia, amplitude and power decreased, and P3 latency increased. Task demands cannot explain increased P3 amplitude, since similarly increased EEG total power was found during no-task resting. Prospective studies must determine whether P3 amplitude and EEG power in nondemented PD patients can serve as predictors of dementia.

Aged↗

PubMed2000

Neural activation during response competition.

The flanker task, introduced by Eriksen and Eriksen [Eriksen, B. A., & Eriksen, C. W. (1974). Effects of noise letters upon the identification of a target letter in a nonsearch task. Perception & Psychophysics, 16, 143--149], provides a means to selectively manipulate the presence or absence of response competition while keeping other task demands constant. We measured brain activity using functional magnetic resonance imaging (fMRI) during performance of the flanker task. In accordance with previous behavioral studies, trials in which the flanking stimuli indicated a different response than the central stimulus were performed significantly more slowly than trials in which all the stimuli indicated the same response. This reaction time effect was accompanied by increases in activity in four regions: the right ventrolateral prefrontal cortex, the supplementary motor area, the left superior parietal lobe, and the left anterior parietal cortex. The increases were not due to changes in stimulus complexity or the need to overcome previously learned associations between stimuli and responses. Correspondences between this study and other experiments manipulating response interference suggest that the frontal foci may be related to response inhibition processes whereas the posterior foci may be related to the activation of representations of the inappropriate responses.

Acoustic Stimulation↗

PubMed1997

Factors influencing mental workload indexes.

Several findings of the author's own mental workload research are reviewed. Especially, factors, except task demand, influencing mental workload indexes are discussed. First, an experiment using the National Aeronautics and Space Administration Task Load Index (NASA TLX) is reviewed and the effects of a prior task load on a subsequent subjective workload are described. In a physiological measures section, the low reliability of the heart rate variability (HRV) parameters when the subjects' respiration pattern are highly irregular, and the existence of low sweat respondent, although perspiration seems to be sensitive to the workload, are indicated. Furthermore, results of the task specific physiological responses and of a HRV parameter affected by the individual characteristics, like type A behavior pattern, are shown. Discrepancy between autonomic nervous system activity measures may be solvable by introducing a new concept of autonomic space (synergism of sympathetic and parasympathetic nervous system). Finally, the need for strategies of data management concerning the individual differences is emphasized.

Autonomic Nervous System↗

PubMed2005

Difficulty of perceptual spatiotemporal integration modulates the neural activity of left inferior parietal cortex.

The integration of spatial and temporal information is a prerequisite for skilled movements. Likewise, spatial and temporal information must be integrated to predict the potential collision (or otherwise) of two moving objects. In a previous blocked functional magnetic resonance imaging (fMRI) study [Neuroimage 20 (2003) S82] we showed that collision judgments (relative to size judgments) provoked a significant increase in neural activity in the left inferior parietal cortex (supramarginal gyrus). This result suggests that this region is involved in the integration of perceptual spatiotemporal information in addition to its known involvement in programming skilled actions. To further investigate the impact of the integration of temporal and spatial information on the left parietal cortex we conducted an event-related fMRI study in which we varied the difficulty of the collision (and the size) judgment tasks parametrically. Reaction times and error rates were used as behavioral measures of increasing task demands. There was a significant linear increase in reaction times and error rates during the collision and the size tasks over the four levels of task difficulty. A linear increase of the blood oxygen level-dependent signal in the left inferior parietal cortex was found only for the collision, not for the size, conditions. Neural activation in the left inferior parietal cortex thus paralleled the increasing demands on spatiotemporal integration. This result confirms that the left supramarginal gyrus integrates spatial and temporal information irrespective of motor demands.

Adult↗

PubMed1990

Interaction of attentional and motor control processes in handwriting.

The interaction between attentional capacity, motor control processes, and strategic adaptations to changing task demands was investigated in handwriting, a continuous (rather than discrete) skilled performance. Twenty-four subjects completed 12 two-minute handwriting samples under instructions stressing speeded handwriting, normal handwriting, or highly legible handwriting. For half of the writing samples, a concurrent auditory monitoring task was imposed. Subjects copied either familiar (English) or unfamiliar (Latin) passages. Writing speed, legibility ratings, errors in writing and in the secondary auditory task, and a derived measure of the average number of characters held in short-term memory during each sample ("planning unit size") were the dependent variables. The results indicated that the ability to adapt to instructions stressing speed or legibility was substantially constrained by the concurrent listening task and by text familiarity. Interactions between instructions, task concurrence, and text familiarity in the legibility ratings, combined with further analyses of planning unit size, indicated that information throughput from temporary storage mechanisms to motor processes mediated the loss of flexibility effect. Overall, the results suggest that strategic adaptations of a skilled performance to changing task circumstances are sensitive to concurrent attentional demands and that departures from "normal" or "modal" performance require attention.

Attention↗

PubMed2003

Right lateral fusiform gyrus dysfunction during facial information processing in schizophrenia.

BACKGROUND: Patients with schizophrenia exhibit facial information processing deficits that likely contribute to their social dysfunction. Whether the deficits involve facial affect and/or identity processing or result from other cognitive abnormalities in schizophrenia remains controversial, and a brain dysfunction specifically related to them has never been reported. If such dysfunction existed, it should be consistently observed across groups of patients and during performance of different facial information processing tasks, independently of whether such tasks demand working memory (WM), semantic, or other cognitive processes. We hypothesized that the right lateral fusiform gyrus (rLFG), one of several human brain areas involved in facial information processing, would consistently show activation abnormalities during both facial affect and identity discrimination in schizophrenia. METHODS: We used functional magnetic resonance imaging to measure brain activation in two groups of six chronic, stable schizophrenic outpatients and two of six age- and gender-matched healthy controls. One group of patients and one of controls performed facial affect-with or without semantic processing-and identity discrimination tasks, and the other two groups WM tasks with facial expression cues and varying attentional demands. RESULTS: Patients from either group failed to activate the rLFG when compared to controls in any task. Other activation abnormalities were task-specific (i.e., seen only during performance of one set of tasks) and not consistently observed in both groups of patients, and thus could not be directly and solely linked to facial information discrimination. CONCLUSIONS: These results indicate a specific rLFG dysfunction during early facial information--identity or affect--processing, independent from other cognitive deficits, in schizophrenia.

Adult↗

PubMed2006

Pain catastrophizing, but not injury/illness sensitivity or anxiety sensitivity, enhances attentional interference by pain.

UNLABELLED: Pain draws on attentional resources, thereby disturbing the pursuit of ongoing activities. Several studies have made use of the primary task paradigm to study the disruptive function of pain on attention. In this paradigm, participants perform an attentionally demanding task, while they are occasionally distracted by mild electrical stimulation. Deterioration in task performance (in terms of speed and accuracy) is then taken as an index of attentional interference. One major finding with this paradigm was that pain catastrophizing enhances attentional interference. The current study aimed to replicate this finding and to explore the possible influence of anxiety sensitivity and injury/illness sensitivity on attentional interference. Healthy volunteers (n = 48) performed an auditory discrimination task and were thereby occasionally distracted by low electrocutaneous stimulations. The performance on the discrimination task was subsequently related to participants' scores on the Pain Catastrophizing Scale, the Anxiety Sensitivity Index, and the Injury/illness Sensitivity Index. We were unable to demonstrate an association of either injury/illness sensitivity or anxiety sensitivity with attentional interference. Results did, however, confirm the finding that pain catastrophizing enhances attentional interference. PERSPECTIVE: The present study showed that pain disrupts ongoing activities. This effect is enlarged in those with high levels of pain catastrophizing and is related to the threatening nature of pain stimuli. The role of anxiety sensitivity and injury/illness sensitivity seems to differ from the role of catastrophizing and needs further research.

Adolescent↗

PubMed2006

Changing frontal contributions to memory before and after medial temporal lobectomy.

Frontal recruitment was characterized using functional magnetic resonance imaging (fMRI) during memory encoding in temporal lobe epilepsy (TLE) patients before and after unilateral medial temporal lobectomy. Twenty-four TLE patients and 12 healthy controls underwent a preoperative fMRI session consisting of verbal and nonverbal incidental memory-encoding tasks that typically lead to robust, lateralized frontal activity in controls. A similar postoperative fMRI session was performed in a subset of patients. Preoperatively, the verbal task resulted in significant additional recruitment of right frontal cortex in left TLE patients, compared with controls. Right TLE patients instead showed typically lateralized frontal activation. Bilateral frontal recruitment has been observed in older adults and in young adults in situations of difficult task demands. Typical right-lateralized patterns of frontal recruitment were found in both patient groups during the nonverbal task, indicating that the bilateral frontal recruitment pattern was engaged dynamically depending on the task. After surgery, left TLE patients regained more lateralized frontal activity. These results demonstrated differences in frontal recruitment in left and right TLE patients. Such differences emerged in specific task settings and were influenced by surgery, suggesting a dynamic mechanism of frontal recruitment that can be obtained in TLE patients, possibly as a response to presurgical dysfunction.

Adaptation, Physiological↗

PubMed2002

Effects of caffeine on performance of low intensity tasks.

31 college age men and women who consume less than three caffeinated beverages per week agreed to participate as subjects in research on the effects of acute caffeine intake on low intensity task performance. All subjects performed two randomly administered test conditions: (1) caffeine (5 mg/kg) and (2) placebo on separate visits following an initial 1-hr. orientation visit. Subjects were administered the beverage 30 min. prior to performing 12 separate tests assessing basic mathematics, simple response, logical reasoning, hand-eye coordination, and spatial and assembly skills. The Spielberger State Anxiety test was administered immediately after consuming the test beverage and once again at posttest. Analysis showed that caffeine did not significantly affect performance on all tests with the exception of the peripheral awareness (hand-eye coordination) test on which performance was higher after ingesting caffeine. The placebo treatment produced no effect on state anxiety, which contrasted with a significant rise in anxiety after caffeine consumption. State anxiety values were significantly greater after caffeine treatment relative to the placebo at pretest, and this difference persisted at posttest. These results demonstrated that the dose of caffeine increased scores on state anxiety for individuals who consumed less than three caffeinated beverages weekly but had very little effect on performance of low intensity tasks, except for a hand-eye coordination test involving peripheral awareness. Perhaps longer continuous performance of more demanding tasks would be more sensitive.

Adult↗

PubMed1999

Selective discrimination learning impairments in mice expressing the human Huntington's disease mutation.

Cognitive decline is apparent in the early stages of Huntington's disease and progressively worsens throughout the course of the disease. Expression of the human Huntington's disease mutation in mice (R6/2 line) causes a progressive neurological phenotype with motor symptoms resembling those seen in Huntington's disease. Here we describe the cognitive performance of R6/2 mice using four different tests (Morris water maze, visual cliff avoidance, two-choice swim tank, and T-maze). Behavioral testing was performed on R6/2 transgenic mice and their wild-type littermates between 3 and 14.5 weeks of age, using separate groups of mice for each test. R6/2 mice did not show an overt motor phenotype until approximately 8 weeks of age. However, between 3.5 and 8 weeks of age, R6/2 mice displayed progressive deterioration in specific aspects of learning in the Morris water maze, visual cliff, two-choice swim tank, and T-maze tasks. The age of onset and progression of the deficits in the individual tasks differed depending on the particular task demands. Thus, as seen in humans with Huntington's disease, R6/2 mice develop progressive learning impairments on cognitive tasks sensitive to frontostriatal and hippocampal function. We suggest that R6/2 mice provide not only a model for studying cognitive and motor changes in trinucleotide repeat disorders, but also a framework within which the functional efficacy of therapeutic strategies aimed at treating such diseases can be tested.

Animals↗

PubMed2000

Understanding awareness deficits following brain injury.

The critical role that awareness deficits play in contributing to rehabilitation outcome and independent functioning of brain injured adults is readily acknowledged by rehabilitation professionals. However, there are inconsistencies in the scope of what is included within the concept of awareness and the way in which it is measured within the literature. A comprehensive model of awareness is needed to guide the development of measurement tools and interventions. This paper expands upon concepts originally proposed by Crosson and colleagues [12] and proposes a comprehensive model of awareness that integrates parallel themes in cognitive psychology, social psychology and neuropsychology. It argues that a hierarchical view of awareness does not capture the complexities and subtleties of awareness symptoms and proposes a dynamic relationship between knowledge, beliefs, task demands and context of a situation. A distinction between knowledge and awareness, that one has prior to a task, and that, which is activated during task performance, is emphasized. Suggestions for expanding assessment and intervention methodology are derived from the perspective of research within the areas of metacognition and self-efficacy.

Journal Article↗

PubMed1986

Electrophysiology of skilled performances in children.

Skilled performance is a result of appropriate integration of sensorimotor, cognitive and motivational functions. When Piaget was asked about the nature of reality and our knowledge of it, he answered: "I know an object only when I can act on it; before this action I cannot say anything about it". It has been proposed that motor actions are the source from which mental operations emerge. The intellectual growth of a child goes through stages during which actions, perceptions and ability for concrete or abstract thought hold in turn a predominant role. On the grounds of this theoretical framework it could be argued that neuropsychophysiological investigations of skilled performance in children which incorporate the study of performance-related brain electrical activity could contribute unique information with theoretical and clinical implications. A pattern of slow and phasic brain electrical activity is consistently associated with the execution of skilled ballistic tasks. The slow potentials of the preparatory period (Bereitschfts Potential-BP) are of low amplitude in low demand tasks and in young children. The potentials closely associated with the execution of the act and reflecting sensory feedback activity (Motor Cortex Potential-MCP) are constantly present in children of all ages. The potential associated with knowledge of results (Skilled Performance Positivity-SPP) is only present if task relevant exteroceptive information is expected and occurs. The SPP is independent of the action itself and of the existence of non-informative exteroceptive stimulation. The SPP is absent in unskilled tasks and in young children. The motor performance related with the execution of the motor act improves with increasing age.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗

PubMed1996

Effects of a single cognitive task on power spectra of R-R interval and arterial blood pressure.

The present study was designed to examine the effects of a single cognitively demanding task on the R-R interval and systolic blood pressure (BP) power spectra. Ten healthy volunteers were asked to perform an English transcription task for 90 minutes using a word processor, and to read books as a non-task control. The influences of both posture and respiration were controlled in assessing the task effects. Performance of the single cognitive task significantly increased the normalized low-frequency component (% LF) of the BP spectrum following the task, as compared to the non-task control in the sitting position. However, the supine position did not produce the post-task increase in % LF of the BP spectrum. The spectral components of the R-R interval spectrum remained unchanged after the task. These results suggest that the post-task increase in sympathetic activity may be reflected by the BP spectrum under sympathetic predominance in the sitting position.

Adult↗

PubMed1998

Processing prosodic and musical patterns: a neuropsychological investigation.

To explore the relationship between the processing of melodic and rhythmic patterns in speech and music, we tested the prosodic and musical discrimination abilities of two "amusic" subjects who suffered from music perception deficits secondary to bilateral brain damage. Prosodic discrimination was assessed with sentence pairs where members of a pair differed by intonation or rhythm, and musical discrimination was tested using musical-phrase pairs derived from the prosody of the sentence pairs. This novel technique was chosen to make task demands as comparable as possible across domains. One amusic subject showed good performance on both linguistic and musical discrimination tasks, while the other had difficulty with both tasks. In both subjects, level of performance was statistically similar across domains, suggesting shared neural resource for prosody and music. Further tests suggested that prosody and music may overlap in the processes used to maintain auditory patterns in working memory.

Adult↗

PubMed1991

The influence of children's facial maturity on parental expectations and punishments.

It was hypothesized that the perception of maturefaced children as more able to follow complicated instructions, more likely to know right from wrong, more shrewd, and physically stronger than their babyfaced peers would lead parents to assign more demanding tasks to these children and to judge their misbehavior more harshly. Study 1 revealed that parents allocated more cognitively demanding, but not more physically demanding, chores to maturefaced 11 year old depicted in photographs than to babyfaced children of the same age and attractiveness. Study 2 revealed that parents perceived the misbehaviors of maturefaced 4- and 11-year-old children as more intentional than those of their babyfaced peers, an effect that was significant only when parents judged children of the opposite sex. Study 2 further revealed that, with perceived intentionality held constant, a babyface mitigated the severity of punishment recommended for relatively serious infractions by preschoolers, while increasing it for older children. The latter finding was discussed in light of other evidence that people react negatively to the disconfirmation of their benign expectations regarding babyfaced individuals, and that parents perceived the misbehaviors as more unexpected for 11 year olds than 4 year olds.

Achievement↗

PubMed1999

Data needs in studies on equity in health and access to care--ethical considerations.

In order to study equity in health and access to care in an appropriate way, data are needed on an individual level and must include information about health, mortality, morbidity, utilization of care, age, sex, residential area, family situation and the social and economic circumstances of each individual. These data must be collected at several points of time during a life cycle. This is a demanding task requiring many resources and methodological and ethical considerations. The ethical and political trade-off is between our demand for knowledge and a fair distribution of resources in order to achieve equity in health and access to care and the need to administrate sensitive data without threatening personal integrity. In presenting results from Swedish studies, it is argued that the benefits of using registers for this kind of epidemiological research by far outweigh the risk of using registers.

Data Interpretation, Statistical↗

PubMed1981

Aging, divided attention, and processing capacity.

The performance of young and old adults was compared in two different situations to investigate the reasons why the latter are especially poor at divided attention tasks. Although the two experimental tasks were quite different, one a single task and the other time-sharing, task difficulty was manipulated in a similar fashion in both situations. Specifically, in both tasks difficulty was varied by manipulation of number of items to be rehearsed and number of mental operations necessary for successful performance. The most salient difference in task demands, that is, divided versus nondivided attention, had little effect on results. Performance of both age groups declined as task difficulty increased, with the decline being greater and more rapid for the older subjects. Results are discussed in terms of competition for limited processing capacity in working memory.

Adolescent↗