Electrophysiological and neuroimaging studies of voluntary and reflexive attention.

Powerful brain systems specialized for voluntary and reflexive attentional control influence visual information processing. Studies of voluntary selective attention have shown that the amplitudes of visual event-related potentials (ERPs) are greater for events occurring at attended locations. Using ERPs, we recently investigated the neural correlates of reflexive attention and found that early visual processing in the cortex is also modulated by reflexive orienting. By integrating functional imaging with ERP recording, we related ERP signs of voluntary attention to underlying neural mechanisms. We used event-related functional magnetic resonance imaging (fMRI) and trial-by-trial spatial cuing to investigate the time course and functional anatomy of these attentional control systems. Attentional mechanisms in frontal, parietal, and temporal cortex were found to produce changes in visual cortical processing at multiple loci in the visual hierarchy, facilitating or attenuating information from competing loci to reduce interference from irrelevant events during perception and performance.