Abstract
A substantial body of work implicates a frontoparietal network as the source of top-down attention in humans. Studies in monkeys have shown that the frontal eye field (FEF) participates in target selection during visual search and top-down attention. Recently, we discovered a monkey homologue of the human N2pc (Woodman GF, Kang M-S, Rossi AF & Schall JD (2007) Nonhuman primate event-related potentials indexing covert shifts of attention. Proc Natl Acad Sci 38, 15111–15116), an ERP component that indexes attention. We now bridge the two bodies of literature by testing the hypothesis that the FEF is a source of top-down attention for visual cortex. We recorded event-related potentials (ERPs) over visual cortex (approximating human 10/20 locations T5 and T6) while simultaneously recording local field potentials (LFPs) and single neuron activity in the FEF of monkeys performing a T/L visual search. Target selection, measured using a common criterion, occurred earliest in the visual cortex ERPs (mean = 165.4 ms), next in the FEF LFPs (182.5 ms), and latest in the 24 FEF neurons (190.9 ms) across sessions. Thus, the FEF appears not to be the source of the monkey homologue of the N2pc.
Supported by NEI R01-EY08890, P30-EY08126 and Ingram Chair of Neuroscience.