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Attentional Modulation (attentional + modulation)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Perceptual load interacts with stimulus processing across sensory modalities

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2009
J. Klemen
Abstract According to perceptual load theory, processing of task-irrelevant stimuli is limited by the perceptual load of a parallel attended task if both the task and the irrelevant stimuli are presented to the same sensory modality. However, it remains a matter of debate whether the same principles apply to cross-sensory perceptual load and, more generally, what form cross-sensory attentional modulation in early perceptual areas takes in humans. Here we addressed these questions using functional magnetic resonance imaging. Participants undertook an auditory one-back working memory task of low or high perceptual load, while concurrently viewing task-irrelevant images at one of three object visibility levels. The processing of the visual and auditory stimuli was measured in the lateral occipital cortex (LOC) and auditory cortex (AC), respectively. Cross-sensory interference with sensory processing was observed in both the LOC and AC, in accordance with previous results of unisensory perceptual load studies. The present neuroimaging results therefore warrant the extension of perceptual load theory from a unisensory to a cross-sensory context: a validation of this cross-sensory interference effect through behavioural measures would consolidate the findings. [source]

Effects of attention and arousal on early responses in striate cortex

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2005
Vahe Poghosyan
Abstract Humans employ attention to facilitate perception of relevant stimuli. Visual attention can bias the selection of a location in the visual field, a whole visual object or any visual feature of an object. Attention draws on both current behavioral goals and/or the saliency of physical attributes of a stimulus, and it influences activity of different brain regions at different latencies. Attentional effect in the striate and extrastriate cortices has been the subject of intense research interest in many recent studies. The consensus emerging from them places the first attentional effects in extrastriate areas, which in turn modulate activity of V1 at later latencies. In this view attention influences activity in striate cortex some 150 ms after stimulus onset. Here we use magnetoencephalography to compare brain responses to foveally presented identical stimuli under the conditions of passive viewing, when the stimuli are irrelevant to the subject and under an active GO/NOGO task, when the stimuli are cues instructing the subject to make or inhibit movement of his/her left or right index finger. The earliest striate activity was identified 40,45 ms after stimulus onset, and it was identical in passive and active conditions. Later striate response starting at about 70 ms and reaching a peak at about 100 ms showed a strong attentional modulation. Even before the striate cortex, activity of the right inferior parietal lobule was modulated by attention, suggesting this region as a candidate for mediating attentional signals to the striate cortex. [source]

Effects of Distraction Versus Spatial Discrimination on Laser-Evoked Potentials in Migraine

HEADACHE, Issue 3 2008
Marina De Tommaso MD
Objectives., To evaluate whether migraine patients exhibit less inhibition to painful stimuli when distracted from pain as compared to healthy subjects, testing the spatial discrimination of painful stimuli, the performance during the mental arithmetic task used to contrast the discrimination performance and the behavior of N1 and N2-P2 laser-evoked potentials (LEPs) amplitudes during spatial discrimination and during distraction. Methods., Eight migraine patients and 8 healthy controls were examined. During repetitive series of painful laser stimulation of the hand, they had to (1) perform a spatial discrimination task, contrasted by (2) a mental arithmetic task that served as distraction. Results., Patients made 50% to 100% more mistakes than controls in the spatial discrimination task (P < .001) as well as during mental arithmetic (P < .05). Whereas healthy subjects showed a marked decrease of the LEP vertex potential amplitudes during distraction compared to the discrimination task, no such attenuation of LEPs was seen in migraine patients (group × task interaction, P < .05). N1 amplitude exhibited a left-hemisphere dominance in both groups, significantly smaller amplitude in migraine patients, but no significant task modulation. Conclusion., Migraine patients exhibited reduced inhibition by attentional modulation of pain processing, accompanied by impaired spatial discrimination of painful stimuli. [source]

Brain mechanisms of involuntary visuospatial attention: An event-related potential study

HUMAN BRAIN MAPPING, Issue 4 2005
Shimin Fu
Abstract The brain mechanisms mediating visuospatial attention were investigated by recording event-related potentials (ERPs) during a line-orientation discrimination task. Nonpredictive peripheral cues were used to direct participant's attention involuntarily to a spatial location. The earliest attentional modulation was observed in the P1 component (peak latency about 130 ms), with the valid trials eliciting larger P1 than invalid trials. Moreover, the attentional modulations on both the amplitude and latency of the P1 and N1 components had a different pattern as compared to previous studies with voluntary attention tasks. In contrast, the earliest visual ERP component, C1 (peak latency about 80 ms), was not modulated by attention. Low-resolution brain electromagnetic tomography (LORETA) showed that the earliest attentional modulation occurred in extrastriate cortex (middle occipital gyrus, BA 19) but not in the primary visual cortex. Later attention-related reactivations in the primary visual cortex were found at about 110 ms after stimulus onset. The results suggest that involuntary as well as voluntary attention modulates visual processing at the level of extrastriate cortex; however, at least some different processes are involved by involuntary attention compared to voluntary attention. In addition, the possible feedback from higher visual cortex to the primary visual cortex is faster and occurs earlier in involuntary relative to voluntary attention task. Hum Brain Mapp, 2005. © 2005 Wiley-Liss, Inc. [source]

Looking for faces: Attention modulates early occipitotemporal object processing

PSYCHOPHYSIOLOGY, Issue 3 2004
Andreas Lueschow
Abstract Looking for somebody's face in a crowd is one of the most important examples of visual search. For this goal, attention has to be directed to a well-defined perceptual category. When this categorically selective process starts is, however, still unknown. To this end, we used magnetoencephalography (MEG) recorded over right human occipitotemporal cortex to investigate the time course of attentional modulation of perceptual processes elicited by faces and by houses. The first face-distinctive MEG response was observed at 160,170 ms (M170). Nevertheless, attention did not start to modulate face processing before 190 ms. The first house-distinctive MEG activity was also found around 160,170 ms. However, house processing was not modulated by attention before 280 ms (90 ms later than face processing). Further analysis revealed that the attentional modulation of face processing is not due to later, for example, back-propagated activation of the M170 generator. Rather, subsequent stages of occipitotemporal object processing were modulated in a category-specific manner and with preferential access to face processing. [source]

Attentional blink modulation during sustained and after discrete lead stimuli presented in three sensory modalities

PSYCHOPHYSIOLOGY, Issue 2 2003
Ottmar V. Lipp
Abstract Previous studies found larger attentional modulation of acoustic blinks during task-relevant than during task-irrelevant acoustic or visual, but not tactile, lead stimuli. Moreover, blink modulation was larger overall during acoustic lead stimuli. The present experiment investigated whether these results reflect modality specificity of attentional blink modulation or effects of continuous stimulation. Participants performed a discrimination and counting task with acoustic, visual, or tactile lead stimuli. Stimuli were presented sustained or consisted of two short discrete stimuli. The sustained condition replicated previous results. In the discrete condition, blinks were larger during task-relevant than during task-irrelevant stimuli in all groups regardless of lead stimulus modality. Thus, previous results that seemed consistent with modality-specific accounts of attentional blink modulation reflect effects of continuous stimulus input. [source]

Automatic and controlled attentional processes in startle eyeblink modification: Effects of habituation of the prepulse

PSYCHOPHYSIOLOGY, Issue 4 2000
Anne M. Schell
The effect of prehabituation of the prepulse on startle eyeblink modification was studied in two experiments. In Experiment 1, college student participants were either prehabituated or nonhabituated to a tone that served as a prepulse in a startle modification passive attention paradigm. Neither short lead interval (60 and 120 ms) prepulse inhibition (PPI) nor long lead interval (2,000 ms) prepulse facilitation (PPF) was affected by the prehabituation procedure. In Experiment 2, participants were presented with an active attention paradigm in which one of two tone prepulses was attended while the other was ignored. One group was prehabituated to the prepulses and the other was not. Unlike the results with the passive paradigm in Experiment 1, prehabituation did significantly diminish attentional modulation of PPI and PPF. These results are consistent with the hypothesis that passive PPI and PPF are primarily automatic processes, whereas attentional modulation involves controlled cognitive processing. [source]