title: On the origin of event-related potentials indexing covert attentional selection during visual search: timing of selection by macaque frontal eye field and event-related potentials during pop-out search.
abstract: Event-related potentials (ERPs) have provided crucial data concerning the time course of psychological processes, but the neural mechanisms producing ERP components remain poorly understood. This study continues a program of research in which we investigated the neural basis of attention-related ERP components by simultaneously recording intracranially and extracranially from macaque monkeys. Here, we compare the timing of attentional selection by the macaque homologue of the human N2pc component (m-N2pc) with the timing of selection in the frontal eye field (FEF), an attentional-control structure believed to influence posterior visual areas thought to generate the N2pc. We recorded FEF single-unit spiking and local field potentials (LFPs) simultaneously with the m-N2pc in monkeys performing an efficient pop-out search task. We assessed how the timing of attentional selection depends on task demands by direct comparison with a previous study of inefficient search in the same monkeys (e.g., finding a T among Ls). Target selection by FEF spikes, LFPs, and the m-N2pc was earlier during efficient pop-out search rather than during inefficient search. The timing and magnitude of selection in all three signals varied with set size during inefficient but not efficient search. During pop-out search, attentional selection was evident in FEF spiking and LFP before the m-N2pc, following the same sequence observed during inefficient search. These observations are consistent with the hypothesis that feedback from FEF modulates neural activity in posterior regions that appear to generate the m-N2pc even when competition for attention among items in a visual scene is minimal.
authors.affiliation: Department of Psychology, Center for Integrative & Cognitive Neuroscience, Vanderbilt Vision Research Center, Vanderbilt University, Nashville, Tennessee 37240-7817, USA.
authors.forename: Braden A
authors.initials: BA
authors.lastname: Purcell
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Schall
authors.forename: Geoffrey F
authors.initials: GF
authors.lastname: Woodman
mesh_terms: D000818:Animals; D001070:Appetitive Behavior; D001288:Attention; D058256:Brain Waves; D002540:Cerebral Cortex / Q000502:physiology; D005074:Evoked Potentials, Visual; D030141:Feedback, Psychological; D008255:Macaca radiata; D008297:Male; D013647:Task Performance and Analysis; D014794:Visual Fields