Search results for "Processes"
showing 10 items of 3831 documents
Parieto-frontal interactions in visual-object and visual-spatial working memory: Evidence from transcranial magnetic stimulation
2001
This study aimed to investigate whether transcranial magnetic stimulation (TMS) can induce selective working memory (WM) deficits of visual-object versus visual-spatial information in normal humans. Thirty-five healthy subjects performed two computerized visual n-back tasks, in which they were required to memorize spatial locations or abstract patterns. In a first series of experiments, unilateral or bilateral TMS was delivered on posterior parietal and middle temporal regions of both hemispheres after various delays during the WM task. Bilateral temporal TMS increased reaction times (RTs) in the visual-object, whereas bilateral parietal TMS selectively increased RTs in the visual-spatial W…
Amplitude envelope correlation detects coupling among incoherent brain signals.
2000
Event-related potentials (ERPs) to changes in the visual environment were recorded in rabbits. In the oddball condition, infrequently presented (deviant) stimuli occurred in a series of frequently presented (standard) stimuli. In the deviant-alone condition, standards were omitted. ERPs to oddball-deviants differed from those to standards in all recording sites (cerebellar cortex, visual cortex, dentate gyrus). No corresponding differences were found between ERPs to deviants in the oddball condition and those in the deviant-alone condition. However, because ERPs to deviants in the deviant-alone condition and those to standards did not differ either, ERPs to stimulus changes in the oddball c…
Neural mechanisms of training an auditory event‐related potential task in a brain–computer interface context
2019
Effective use of brain-computer interfaces (BCIs) typically requires training. Improved understanding of the neural mechanisms underlying BCI training will facilitate optimisation of BCIs. The current study examined the neural mechanisms related to training for electroencephalography (EEG)-based communication with an auditory event-related potential (ERP) BCI. Neural mechanisms of training in 10 healthy volunteers were assessed with functional magnetic resonance imaging (fMRI) during an auditory ERP-based BCI task before (t1) and after (t5) three ERP-BCI training sessions outside the fMRI scanner (t2, t3, and t4). Attended stimuli were contrasted with ignored stimuli in the first-level fMRI…
Climate uniformity: its influence on team communication quality, task conflict, and team performance.
2014
We investigated whether climate uniformity (the pattern of climate perceptions of organizational support within the team) is related to task conflict, team communication quality, and team performance. We used a sample composed of 141 bank branches and collected data at 3 time points. The results obtained showed that, after controlling for aggregate team climate, climate strength, and their interaction, a type of nonuniform climate pattern (weak dissimilarity) was directly related to task conflict and team communication quality. Teams with weak dissimilarity nonuniform patterns tended to show higher levels of task conflict and lower levels of team communication quality than teams with unifor…
Nonlinear analysis of sleep EEG data in schizophrenia: calculation of the principal Lyapunov exponent
1995
The generating mechanism of the electroencephalogram (EEG) points to the hypothesis that EEG signals derive from a nonlinear dynamic system. Hence, the unpredictability of the EEG might be considered as a phenomenon exhibiting its chaotic character. The essential property of chaotic dynamics is the so-called sensitive dependence on initial conditions. This property can be quantified by calculating the system's first positive Lyapunov exponent, L1. We calculated L1 for sleep EEG segments of 13 schizophrenic patients and 13 control subjects that corresponded to sleep stages I, II, III, IV and REM (rapid eye movement), as defined by Rechtschaffen and Kales, for the lead positions Cz and Pz. Du…
Functional properties of the brain during sleep under subchronic zopiclone administration in man.
1994
Zopiclone, a non-benzodiazepine, has been shown to be efficient in the treatment of transient, short-term or chronic sleep disorders. Apart from its hypnotic effects zopiclone has anxiolytic, anticonvulsant and myorelaxant properties and is therefore hardly distinguishable from benzodiazepines. Dependence liability and discontinuation effects have been reported to be less pronounced. Therefore zopiclone seems to be a hypnotic drug which may cause fewer side effects than conventional benzodiazepines. From the electrophysiological point of view one requires from a hypnotic drug the induction of a physiological sleep pattern as well as no alterations of information processing by the brain. The…
Gray matter alteration in dyslexia: converging evidence from volumetric and voxel-by-voxel MRI analyses.
2004
Affecting up to 4-10% of the population, dyslexia is a highly prevalent, childhood onset developmental disorder adversely influencing multiple domains of adaptive functioning throughout the lifespan. The present brain imaging study was conducted in order to investigate the neuroanatomical correlates of developmental dyslexia. The MRI brain scans of 10 males with dyslexia and 14 matched controls were analyzed with (1) a classical volumetric method measuring gray and white matter lobar volumes and (2) a voxel-by-voxel method. The voxel-by-voxel method identifies changes in tissue density and localizes morphologic alterations without limiting the analyses to predefined regions. Subsequent corr…
Brain responses of dysphoric and control participants during a self-esteem implicit association test.
2021
Previous studies have reported lowered implicit self-esteem at the behavioral level among depressed individuals. However, brain responses related to the lowered implicit self-esteem have not been investigated in people with depression. Here, event-related potentials were measured in 28 dysphoric participants (individuals with elevated amounts of depressive symptoms) and 30 control participants during performance of an implicit association task (IAT) suggested to reflect implicit self-esteem. Despite equivalent behavioral performance, differences in brain responses were observed between the dysphoric and the control groups in late positive component (LPC) within 400-1,000 ms poststimulus lat…
Factors Influencing Tinnitus Loudness and Annoyance
2006
Objective To evaluate the 2 major components of tinnitus severity, loudness and annoyance, and their degree of dependence on characteristics of tinnitus manifestation, history, and etiology. Design Cross-sectional survey performed during the first months of 2004. Setting Nonclinical population. Participants A total of 4995 members of the German Tinnitus League. Main Outcome Measures Comprehensive screening questionnaire, including the Klockhoff and Lindblom loudness grading system and the miniversion of the Tinnitus Questionnaire. Results A moderate correlation of 0.45 was found between tinnitus loudness and annoyance. Both factors were generally higher in men, those older than 50 years, th…
What happens when we get angry? Hormonal, cardiovascular and asymmetrical brain responses
2010
This study aimed to evaluate neuroendocrine and cardiovascular responses together with changes in brain asymmetry following an anger mood induction laboratory task. Previous research has shown an increase in heart rate and blood pressure when anger is experienced. Increased testosterone and decreased cortisol in response to anger and aggressive behavior have also been reported. With regard to asymmetrical frontal brain activity and emotion, the valence model links negative affect (as anger) to the right hemisphere while the motivational direction model links approach-related emotions (as anger) to the left hemisphere. From the subjective perception and from the neuroendocrine and cardiovasc…