1,721,250 research outputs found
The orienting of attention during eye and hand movements: ERP evidence for similar frame of reference but different spatially-specific modulations of tactile processing
No full textTo investigate which frames of reference guide shifts of attention triggered during eye and hand movement preparation and the specificity of their effects on somatosensory processing, we recorded event-related brain potentials (ERPs) in a Go/Nogo task where a cue indicated to prepare an eye movement toward – or a hand movement with – the left or right hand. Before the imperative stimulus, a tactile probe was presented to one hand. Spatially selective modulations of tactile processing were more sustained for hand than eye movements, indicating stronger attentional modulations for the modality of the effector's sensory organ. Importantly, attentional modulations of somatosensory processing as well as lateralized ERP components in the preparation interval were virtually identical under uncrossed and crossed hands conditions, suggesting that shifts of attention triggered during hand and eye movement preparation are guided by a common external reference frame
ERP investigations into the effects of gaze and spatial attention on the processing of tactile events. International Multisensory Research Forum, IMRF, Oxford, UK.
No full textMultivariate complex B-splines, Dirichlet averages, and difference operators.
No full textFor the Schoenberg B-splines, interesting relations between their functional representation, Dirichlet averages and difference operators are known. We use these relations to extend the B-splines to an arbitrary (infinite) sequence of knots and to higher dimensions. A new Fourier domain representation of the multidimensional complex B-spline is given
ERP investigation of the reference frames that guide shifts of attention triggered during covert tactile-spatial orienting and manual movement preparation. International Conference on Cognitive Neuroscience, ICON XI, Mallorca, Spain.
No full textThe spatial reference frames employed during hand and eye movement preparation: Evidence from lateralized ERP components. Society for Psychophysiological Research, Portland, USA.
No full textCrossing the hands disrupts tactile spatial attention but not motor attention: Evidence from event-related potentials
No full textDuring covert shifts of tactile spatial attention both somatotopic and external reference frames are employed to encode hand location. When participants cross their hands these frames of references produce conflicting spatial codes which disrupt tactile attentional selectivity. Because attentional shifts are triggered not only in Attention tasks but also during covert movement preparation, the present study aimed at investigating the reference frame employed during such 'motor shifts of attention'. Event related brain potentials (ERPs) were recorded during a Motor task where a visual cue (S1) indicated the relevant hand for a manual movement prior to a tactile Go/Nogo stimulus (S2). For comparison, we ran a tactile Attention task where the same cue (S1) now indicated the relevant hand for a tactile discrimination (S2). Both tasks were performed under uncrossed and crossed hands conditions. In both Attention and Motor tasks similar lateralized components were observed following S1 presentation. Anterior and posterior ERP components indicative of covert attention shifts were exclusively guided by an external reference frame, while a later central negativity operated according to a somatotopic reference frame in both tasks. In the Motor task, this negativity reflected selective activation of the motor cortex in preparation for movement execution. In the Attention task, this component might reflect activity in the somatosensory cortex in preparation for the subsequent tactile discrimination. The presence of multiple and conflicting spatial codes resulted in disruption of tactile attentional selection in the Attention task where attentional modulations of tactile processing were delayed and attenuated with crossed hands as indicated by the analysis of ERPs elicited by S2. In contrast, attentional modulations of S2 processing in the Motor task were largely unaffected by the hand posture manipulation, suggesting that motor attention employs primarily one spatial coordinate system
Independent effects of eye gaze and spatial attention on the processing of tactile events: Evidence from event-related potentials
Full text linkDirecting one’s gaze at a body part reduces detection speed and enhances the processing of tactile stimuli presented at the gazed location. Given the close links between spatial attention and the oculomotor system it is possible that these gaze-dependent modulations of touch are mediated by attentional mechanisms. To investigate this possibility, gaze direction and sustained tactile attention were orthogonally manipulated in the present study. Participants covertly attended to one hand to perform a tactile target-nontarget discrimination while they gazed at the same or opposite hand. Spatial attention resulted in enhancements of the somatosensory P100 and Nd components. In contrast, gaze resulted in modulations of the N140 component with more positive ERPs for gazed than non gazed stimuli. This dissociation in the pattern and timing of the effects of gaze and attention on somatosensory processing reveals that gaze and attention have independent effects on touch
Earth observation: data, processing and applications
No full textHarrison, B.A., Jupp, D.L.B., Lewis, M.M., Forster, B., Mueller, N., Smith, C., Phinn, S., Hudson, D., Grant, I., Coppa, I
Attention to the body depends on eye-in-orbit position
Full text linkAttentional selectivity in touch is modulated by the position of the body in external space. For instance, during endogenous attention tasks in which tactile stimuli are presented to the hands, the effect of attention is reduced when the hands are placed far apart than when they are close together and when the hands are crossed as compared to when they are placed in their anatomical position. This suggests that both somatotopic and external spatial reference frames coding the hands’ locations contribute to the spatial selection of the relevant hand. Here we investigate whether tactile selection of hands is also modulated by the position of other body parts, not directly involved in tactile perception, such as eye-in-orbit (gaze direction). We asked participants to perform the same sustained tactile attention task while gazing laterally towards an eccentric fixation point (Eccentric Gaze) or towards a central fixation point (Central Gaze). SEPs recorded in response to tactile non-target stimuli presented to the attended or unattended hand were compared as a function of gaze direction (Eccentric vs. Central conditions). Results revealed that attentional modulations were reduced in the Eccentric gaze condition as compared to the Central gaze condition in the time range of the Nd component (200-260 ms post-stimulus), demonstrating for the first time that the attentional selection of one of the hands is affected by the position of the eye in the orbit. Directing the eyes towards an eccentric position might be sufficient to create a misalignment between external and somatotopic frames of references reducing tactile attention. This suggests that the eye-in-orbit position contributes to the spatial selection of the task relevant body part
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