Response coding and visuomotor transformation in the Simon task: The role of action goals.

Manual responses can be defined by differing response parameters. Any of them may generate a Simon effect. For all those response parameters, the same implementation of the Simon effect (in terms of subserving mechanism) is assumed. In 3 experiments, subjects had to respond with either fingers or sticks. Temporal properties of the Simon effect changed with response parameters relevant in a task. The Simon effect for manual responses decayed. For stick responses, in which the action goal differed from the anatomical mapping of the acting hand, a sustained Simon effect was observed. However, if the action goal for stick responses was not instrumental for selecting the correct response, the Simon effect decayed. The findings are consistent with the notion of different mechanisms involved in generating a Simon effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Increasing the water uptake of wood veneers through plasma treatment at atmospheric pressure

In order to provide a database which documents the influence of plasma treatment on water uptake of wood veneers, veneers of 27 wood species underwent immersion tests in untreated and plasma-treated states. Plasma treatment was executed using an air driven dielectric barrier discharge at atmospheric pressure. The results showed that plasma treatment led to significantly improved water uptake for most of the wood species, but some wood species remained unaffected after plasma treatment.     

Response force and reaction time in a simple reaction task under time pressure

The aim of this study was to examine the effect of effort on timing and force of simple reactions. To do this, we performed an experiment, arranged like a video-game, in which these variables were measured under different time-pressure conditions. In accordance with our expectations reaction time was shorter and force amplitude larger when the time for responses was limited. These findings are discussed within the framework of Sanders' (1983) model of stress.     

On-line brain potential correlates of right parietal patients' attentional deficit

EEG potentials evoked by cues and targets were recorded in Posner's visual cueing task from 10 patients with lesions of the right parietal cortex and from age-matched healthy subjects. The patients' N1 component evoked by left-side cues was reduced at the right-parietal recording site, suggesting a general impairment in processing left-side visual input. As usual, patients' keypress responses were delayed when left targets were preceded by right cues. There were two correlates of this delay in the patients' EEG potentials evoked by the critical combination of right cue/left target: their mean amplitude 160-280 ms after target onset ('Nd') was less negative than with other combinations of cue and target, and the following frontal P300 was enhanced. The Nd reduction seems to be an on-line measure of patients' momentary decrease of attention for the left hemifield, while the frontal P300 might reflect the patients' attempts at reorienting. In conclusion, different components were sensitive to different aspects of the patients' disorder, suggesting the utility of this approach for developing detailed hypotheses on the mechanisms of attentional deficits involved in visual extinction and neglect.     

Lateralized human cortical activity for shifting visuospatial attention and initiating saccades

Lateralized human cortical activity for shifting visuospatial attention and initiating saccades. J. Neurophysiol. 80: 2900-2910, 1998. The relation between shifts of visual attention and saccade preparation was investigated by studying their electrophysiological correlates in human scalp-recorded electroencephalogram (EEG). Participants had to make saccades either to a saliently colored or to a gray circle, simultaneously presented in opposite visual hemifields, under different task instructions. EEG was measured within the short interval between stimulus onset and saccade, focusing on lateralized activity, contralateral either to the side of the relevant stimulus or to the direction of the saccade. Three components of lateralization were found: 1) activity contralateral to the relevant stimulus irrespective of saccade direction, peaking 250 ms after stimulus onset, largest above lateral parietal sites, 2) activity contralateral to the relevant stimulus if the stimulus was also the target of the saccade, largest 330-480 ms after stimulus onset, widespread over the scalp but with a focus again above lateral parietal sites, and 3) activity contralateral to saccade direction, beginning about 100 ms before the saccade, largest above mesial parietal sites, with some task-dependent fronto-central contribution. Because of their sensitivity to task variables, component 1 is interpreted as the shifting of attention to the relevant stimulus, component 2 is interpreted as reflecting the enhancement of the attentional shift if the relevant stimulus is also the saccade target, and component 3 is interpreted as the triggering signal for saccade execution. Thus human neurophysiological data provided evidence both for independent and interdependent processes of saccade preparation and shifts of visual attention.     

Reconstruction of chronic rupture of the extensor mechanism after patellectomy

Chronic extensor mechanism ruptures are uncommon but challenging clinical problems. Previously published procedures for treating chronic extensor mechanism ruptures assume an intact patella is available to anchor the repair. A case is presented of a patient who had a previous patellectomy, followed by rupture of the extensor mechanism. After two failed attempts at repair, an Achilles tendon allograft was used successfully to restore function of the extensor mechanism. The described technique offers an alternative for reconstruction of the extensor mechanism after patellectomy.     

Clinical value of the various methods of ACTH determination

Eight groups of 1-day-old chickens were inoculated with 0, 250, 5000, or 100,000 white blood cells of chickens infected with Marek's disease virus strain K (MDV-WBC). Four of these groups were additionally infected with 10(5) TCID50 chicken anaemia virus (CAV). At day 14 after inoculation, chickens infected with CAV had reduced haematocrit levels, reduced body weights, and depletion of the thymic cortex and bone marrow. Semi-quantitative immunohistochemical examination of nerves and visceral organs was performed at day 28 by immunoperoxidase staining in which a monoclonal antibody specific for leucocytes was used. CAV significantly enhanced the number of lymphoproliferative lesions induced by 5000 MDV-WBC. In contrast, CAV significantly reduced the number of lymphoproliferative lesions induced by 100,000 MDV-WBC. Comparable results were found at day 61 after macroscopic examination of nerves and visceral organs. These findings show that the pathogenesis of MD in experimental infections appears to be enhanced or inhibited by CAV, depending on the dose of MDV.     

The interaction of stimulus- and response-related processes measured by event-related lateralizations of the EEG

The present study focused on the relationship between movement- and stimulus-related asymmetries of the electroencephalogram (EEG). In seven tasks the same bilateral stimuli containing asymmetric information were presented but response requirements differed. Three functionally distinct asymmetries were found: (1) an asymmetry over the motor cortex prior to unimanual movements, (2) an asymmetry over the posterior cortex beginning about 20 ms after the start of the movement, and (3) an early increase of negativity contralateral to a relevant stimulus (200-300 ms after stimulus onset) that was maximal at temporo-parietal sites but was also visible at central sites. Although related to stimulus side, this asymmetry was modulated by response requirements: it was largely abolished with simple responses, smaller with nogo than with Go stimuli and occurred twice when a sequence of simple and choice responses was required. Therefore, the early temporo-parietal asymmetry most probably reflects an interface between sensory and movement-related processes.