Dissociating top-down attentional control from selective perception and action

Research into the neural mechanisms of attention has revealed a complex net work of brain regions that are involved in the execution of attention-deman ding tasks. Recent advances in human neuroimaging now permit investigation of the elementary processes of attention being subserved by specific compon ents of the brain's attention system. Here we describe recent studies of sp atial selective attention that made use of positron emission tomography (PE T), functional magnetic resonance imaging (fMRI), and event-related brain p otentials (ERPs) to investigate the spatio-temporal dynamics of the attenti on-related neural activity. We first review the results from an event-relat ed fMRI study that examined the neural mechanisms underlying top-down atten tional control versus selective sensory perception. These results defined a fronto-temporal-parietal network involved in the control of spatial attent ion. Activity in these areas biased the neural activity in sensory brain st ructures coding the spatial locations of upcoming target stimuli, preceding a modulation of subsequent target processing in visual cortex. We then pre sent preliminary evidence from a fast-rate event-related fMRI study of spat ial attention that demonstrates how to disentangle the potentially overlapp ing hemodynamic responses elicited by temporally adjacent stimuli in studie s of attentional control. Finally, we present new analyses from combined ne uroimaging (PET) and event-related brain potential (ERP) studies that toget her reveal the timecourse of activation of brain regions implicated in atte ntional control and selective perception. (C) 2001 Elsevier Science Ltd. Al l rights reserved.