Effects of Multimodal Load on Spatial Monitoring as Revealed by ERPs.
While the role of selective attention in filtering out irrelevant information has been extensively studied, its characteristics and neural underpinnings when multiple environmental stimuli have to be processed in parallel are much less known. Building upon a dual-task paradigm that induced spatial awareness deficits for contralesional hemispace in right hemisphere-damaged patients, we investigated the electrophysiological correlates of multimodal load during spatial monitoring in healthy participants. The position of appearance of briefly presented, lateralized targets had to be reported either in isolation (single task) or together with a concurrent task, visual or auditory, which recruited additional attentional resources (dual-task). This top-down manipulation of attentional load, without any change of the sensory stimulation, modulated the amplitude of the first positive ERP response (P1) and shifted its neural generators, with a suppression of the signal in the early visual areas during both visual and auditory dual tasks. Furthermore, later N2 contralateral components elicited by left targets were particularly influenced by the concurrent visual task and were related to increased activation of the supramarginal gyrus. These results suggest that the right hemisphere is particularly affected by load manipulations, and confirm its crucial role in subtending automatic orienting of spatial attention and in monitoring both hemispaces.
Department of Experimental Psychology, Ghent University, Ghent, Belgium; Department of General Psychology, University of Padova, Padova, Italy.
Mario
M
Bonato
Department of General Psychology, University of Padova, Padova, Italy; Center for Cognitive Neuroscience, University of Padova, Padova, Italy.
Chiara
C
Spironelli
Laboratoire Psychologie de la Perception (CNRS UMR 8242), Université Paris Descartes, Paris, France; Department of General Psychology, University of Padova, Padova, Italy.
Matteo
M
Lisi
Department of General Psychology, University of Padova, Padova, Italy.
Konstantinos
K
Priftis
Department of General Psychology, University of Padova, Padova, Italy; Center for Cognitive Neuroscience, University of Padova, Padova, Italy; IRCSS San Camillo Hospital, Lido-Venice, Italy.
Marco
M
Zorzi
D000161:Acoustic Stimulation; D000328:Adult; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D013647:Task Performance and Analysis; D055815:Young Adult