Oscillatory alpha-band mechanisms and the deployment of spatial attention to anticipated auditory and visual targetlocations: Supramodal or sensory-specific control mechanisms?

Oscillatory alpha-band activity (8 -15 Hz) over parieto-occipital cortex in humans plays an important role in suppression of processingfor inputs at to-be-ignored regions of space, with increased alpha-band power observed over cortex contralateral to locations expected tocontain distractors. It is unclear whether similar processes operate during deployment of spatial attention in other sensory modalities.Evidence from lesion patients suggests that parietal regions house supramodal representations of space. The parietal lobes are prominentgenerators of alpha oscillations, raising the possibility that alpha is a neural signature of supramodal spatial attention. Furthermore,when spatial attention is deployed within vision, processing of task-irrelevant auditory inputs at attended locations is also enhanced,pointing to automatic links between spatial deployments across senses. Here, we asked whether lateralized alpha-band activity is alsoevident in a purely auditory spatial-cueing task and whether it had the same underlying generator configuration as in a purely visuospatialtask. If common to both sensory systems, this would provide strong support for "supramodal" attention theory. Alternately, alphabanddifferences between auditory and visual tasks would support a sensory-specific account. Lateralized shifts in alpha-band activitywere indeed observed during a purely auditory spatial task. Crucially, there were clear differences in scalp topographies of this alphaactivity depending on the sensory system within which spatial attention was deployed. Findings suggest that parietally generated alphabandmechanisms are central to attentional deployments across modalities but that they are invoked in a sensory-specific manner. Thedata support an "interactivity account," whereby a supramodal system interacts with sensory-specific control systems during deploymentof spatial attention. Copy; 2011 the authors.