2,654 research outputs found

    Bacteria Hunt: A multimodal, multiparadigm BCI game

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    Brain-Computer Interfaces (BCIs) allow users to control applications by brain activity. Among their possible applications for non-disabled people, games are promising candidates. BCIs can enrich game play by the mental and affective state information they contain. During the eNTERFACE’09 workshop we developed the Bacteria Hunt game which can be played by keyboard and BCI, using SSVEP and relative alpha power. We conducted experiments in order to investigate what difference positive vs. negative neurofeedback would have on subjects’ relaxation states and how well the different BCI paradigms can be used together. We observed no significant difference in mean alpha band power, thus relaxation, and in user experience between the games applying positive and negative feedback. We also found that alpha power before SSVEP stimulation was significantly higher than alpha power during SSVEP stimulation indicating that there is some interference between the two BCI paradigms

    High-frequency neural oscillations and visual processing deficits in schizophrenia

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    Visual information is fundamental to how we understand our environment, make predictions, and interact with others. Recent research has underscored the importance of visuo-perceptual dysfunctions for cognitive deficits and pathophysiological processes in schizophrenia. In the current paper, we review evidence for the relevance of high frequency (beta/gamma) oscillations towards visuo-perceptual dysfunctions in schizophrenia. In the first part of the paper, we examine the relationship between beta/gamma band oscillations and visual processing during normal brain functioning. We then summarize EEG/MEG-studies which demonstrate reduced amplitude and synchrony of high-frequency activity during visual stimulation in schizophrenia. In the final part of the paper, we identify neurobiological correlates as well as offer perspectives for future research to stimulate further inquiry into the role of high-frequency oscillations in visual processing impairments in the disorder

    Psychophysical performance, contingent negative variations, visually evoked cortical potentials, and selective attention : a behavioral and neurophysiological assessment of learning disabilities in children

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    The present experiment was designed to assess whether any attentional, perceptual, or neurophysiological differences exist between children classified as reading disabled and normal. A visual discrimination task was employed, which required attentional and perceptual capabilities; wherein the children were required to selectively attend and respond to one stimulus of a pair and to ignore the other stimulus. Four pairs of stimuli (colors, line orientations, letters, and words) of different levels of complexity were discriminated in order to provide clues as to the possible level of neural processing accounting for the reading disability. The children's ability to attend and to discriminate each stimulus in a pair was measured both behaviorally by psychophysical measures of response accuracy (d’) and reaction time, and also electrophysiologically by visually evoked cortical potentials (VEPs) and contingent negative variations (CNVs). A secondary purpose of the study was to examine whether the learning disability was restricted to one sensory modality. Children who were diagnosed as having either a visual or an auditory disability participated in the experiment so as to determine whether only the visual learning disability children would have difficulty with the visual discrimination task. Therefore, three groups of subjects, matched for age, sex, and IQ, were employed: normal controls (NC), visual learning disabled (VLD), and auditory learning disabled (ALD)

    Distilling the neural correlates of conscious somatosensory perception

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    The ability to consciously perceive the world profoundly defines our lives as human beings. Somehow, our brains process information in a way that allows us to become aware of the images, sounds, touches, smells, and tastes surrounding us. Yet our understanding of the neurobiological processes that generate perceptual awareness is very limited. One of the most contested questions in the neuroscientific study of conscious perception is whether awareness arises from the activity of early sensory brain regions, or instead requires later processing in widespread supramodal networks. It has been suggested that the conflicting evidence supporting these two perspectives may be the result of methodological confounds in classical experimental tasks. In order to infer participants’ perceptual awareness in these tasks, they need to report the contents of their perception. This means that the neural signals underlying the emergence of perceptual awareness often cannot be dissociated from pre- and postperceptual processes. Consequently, some of the previously observed effects may not be correlates of awareness after all but instead may have resulted from task requirements. In this thesis, I investigate this possibility in the somatosensory modality. To scrutinise the task dependence of the neural correlates of somatosensory awareness, I developed an experimental paradigm that controls for the most common experimental confounds. In a somatosensory-visual matching task, participants were required to detect electrical target stimuli at ten different intensity levels. Instead of reporting their perception directly, they compared their somatosensory percepts to simultaneously presented visual cues that signalled stimulus presence or absence and then reported a match or mismatch accordingly. As a result, target detection was decorrelated from working memory and reports, the behavioural relevance of detected and undetected stimuli was equated, the influence of attentional processes was mitigated, and perceptual uncertainty was varied in a controlled manner. Results from a functional magnetic resonance imaging (fMRI) study and an electroencephalography (EEG) study showed that, when controlled for task demands, the neural correlates of somatosensory awareness were restricted to relatively early activity (~150 ms) in secondary somatosensory regions. In contrast, late activity (>300 ms) indicative of processing in frontoparietal networks occurred irrespective of stimulus awareness, and activity in anterior insular, anterior cingulate, and supplementary motor cortex was associated with processing perceptual uncertainty and reports. These results add novel evidence to the early-local vs. late-global debate and favour the view that perceptual awareness emerges at the level of modality-specific sensory cortices.Die FĂ€higkeit zur bewussten Wahrnehmung bestimmt maßgeblich unser Selbstbild als Menschen. Unser Gehirn verarbeitet Informationen auf eine Weise, die es uns ermöglicht, uns der Bilder, Töne, BerĂŒhrungen, GerĂŒche und GeschmĂ€cker, die uns umgeben, bewusst zu werden. Unser VerstĂ€ndnis davon, wie neurobiologische Prozesse diese bewusste Wahrnehmung erzeugen, ist jedoch noch sehr begrenzt. Eine der umstrittensten Fragen in der neurowissenschaftlichen Erforschung des perzeptuellen Bewusstseins besteht darin, ob die bewusste Wahrnehmung aus der AktivitĂ€t frĂŒher sensorischer Hirnregionen entsteht, oder aber die spĂ€tere Prozessierung in ausgedehnten supramodalen Netzwerken erfordert. Eine mögliche ErklĂ€rung fĂŒr die widersprĂŒchlichen Ergebnisse, die diesen beiden Perspektiven zugrunde liegen, wird in methodologischen Störfaktoren vermutet, die in klassischen experimentellen Paradigmen auftreten können. Um auf die Wahrnehmung der Versuchspersonen schließen zu können, mĂŒssen diese den Inhalt ihrer Wahrnehmung berichten. Das fĂŒhrt dazu, dass neuronale Korrelate bewusster Wahrnehmung hĂ€ufig nicht sauber von prĂ€- und postperzeptuellen Prozessen getrennt werden können. Folglich könnten einige der zuvor beobachteten Effekte, anstatt tatsĂ€chlich bewusste Wahrnehmung widerzuspiegeln, aus den Anforderungen experimenteller Paradigmen entstanden sein. In dieser Arbeit untersuche ich diese Möglichkeit in der somatosensorischen ModalitĂ€t. Um zu ĂŒberprĂŒfen, inwiefern neuronale Korrelate bewusster somatosensorischer Wahrnehmung von den Anforderungen experimenteller Aufgaben abhĂ€ngen, habe ich ein Paradigma entwickelt, dass die hĂ€ufigsten experimentellen Störfaktoren kontrolliert. In einer somatosensorisch-visuellen Vergleichsaufgabe mussten die Versuchspersonen elektrische Zielreize in zehn verschiedenen IntensitĂ€tsstufen detektieren. Anstatt diese jedoch direkt zu berichten, sollten sie ihre somatosensorischen Perzepte mit gleichzeitig prĂ€sentierten visuellen Symbolen vergleichen, die entweder Reizanwesenheit oder -abwesenheit signalisierten. Entsprechend wurde dann eine Übereinstimmung oder NichtĂŒbereinstimmung berichtet. Dadurch wurde die Reizwahrnehmung von ArbeitsgedĂ€chtnis und Berichterstattung dekorreliert, die Verhaltensrelevanz detektierter und nicht detektierter Reize gleichgesetzt, der Einfluss von Aufmerksamkeitsprozessen reduziert und die mit der Detektion verbundene Unsicherheit auf kontrollierte Weise variiert. Die Ergebnisse aus einer funktionellen Magnetresonanztomographie (fMRT)-Studie und einer Elektroenzephalographie (EEG)-Studie zeigen, dass die neuronalen Korrelate bewusster somatosensorischer Wahrnehmung auf relativ frĂŒhe AktivitĂ€t (~150 ms) in sekundĂ€ren somatosensorischen Regionen beschrĂ€nkt sind, wenn experimentelle Störfaktoren kontrolliert werden. Im Gegensatz dazu trat spĂ€te AktivitĂ€t (>300 ms), die auf die Verarbeitung in frontoparietalen Netzwerken hindeutet, unabhĂ€ngig von der Reizwahrnehmung auf, und AktivitĂ€t im anterioren insulĂ€ren, anterioren cingulĂ€ren und supplementĂ€r-motorischen Kortex war mit der Verarbeitung von Detektionsunsicherheit und der Berichterstattung verbunden. Diese Ergebnisse liefern neue Erkenntnisse zur Debatte um die Relevanz frĂŒher, lokaler vs. spĂ€ter, globaler HirnaktivitĂ€t und unterstĂŒtzen die Ansicht, dass perzeptuelles Bewusstsein in modalitĂ€tsspezifischen sensorischen Kortizes entsteht

    Aerospace medicine and biology: A continuing bibliography with indexes (supplement 315)

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    This bibliography lists 211 reports, articles and other documents introduced into the NASA scientific and technical information system in September, 1988
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