Abstract
A role for the frontal eye fields (FEFs) in visual search has been supported by converging evidence from numerous cognitive neuroscience approaches, including fMRI and TMS in humans and single-cell recording and inactivation studies in monkeys. However, evidence for FEF involvement from human focal lesion studies is conspicuously absent from the literature. Here, we report data from feature and conjunction search tasks in patients with focal FEF lesions and controls. For both search tasks, arrays of either four or eight search items were used to calculate set size effects. To diminish the influence of response on visual search, we employed an adaptive procedure which estimated the stimulus duration necessary for 75% accuracy in each task. Importantly, target detection was assessed separately for the left and right visual fields, and left and right staircases were interleaved within a block. As in healthy participants, patients required longer presentation durations for conjunction compared to feature search. Initial results from two patients with right FEF lesions indicate that the set size effect in contralesional conjunction search was disproportionately impaired compared to ipsilesional conjunction search. Results will be discussed in the context of other neurodisruptive findings.