title: Preparatory attention in visual cortex.
abstract: Top-down attention is the mechanism that allows us to selectively process goal-relevant aspects of a scene while ignoring irrelevant aspects. A large body of research has characterized the effects of attention on neural activity evoked by a visual stimulus. However, attention also includes a preparatory phase before stimulus onset in which the attended dimension is internally represented. Here, we review neurophysiological, functional magnetic resonance imaging, magnetoencephalography, electroencephalography, and transcranial magnetic stimulation (TMS) studies investigating the neural basis of preparatory attention, both when attention is directed to a location in space and when it is directed to nonspatial stimulus attributes (content-based attention) ranging from low-level features to object categories. Results show that both spatial and content-based attention lead to increased baseline activity in neural populations that selectively code for the attended attribute. TMS studies provide evidence that this preparatory activity is causally related to subsequent attentional selection and behavioral performance. Attention thus acts by preactivating selective neurons in the visual cortex before stimulus onset. This appears to be a general mechanism that can operate on multiple levels of representation. We discuss the functional relevance of this mechanism, its limitations, and its relation to working memory, imagery, and expectation. We conclude by outlining open questions and future directions.
authors.affiliation: Center for Mind/Brain Sciences, University of Trento, Rovereto, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Battistoni
authors.affiliation: Center for Mind/Brain Sciences, University of Trento, Rovereto, Italy.|Department of Psychology, University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Timo
authors.initials: T
authors.lastname: Stein
authors.affiliation: Center for Mind/Brain Sciences, University of Trento, Rovereto, Italy.
authors.forename: Marius V
authors.initials: MV
authors.lastname: Peelen
mesh_terms: D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography / Q000379:methods; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D015225:Magnetoencephalography / Q000379:methods; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D014793:Visual Cortex / Q000000981:diagnostic imaging* / Q000502:physiology
keywords: biased competition; neuroimaging; search template; top-down attention; visual search