Prefrontal control of visual distraction

Avoiding distraction by salient irrelevant stimuli is critical to accomplishing daily tasks. Regions of prefrontal cortex control attention by enhancing the representation of task-relevant information in sensory cortex, which can be measured directly in modulation of both single neurons and averaging of the scalp-recorded electroencephalogram [1,2]. However, when irrelevant information is particularly conspicuous, it may distract attention and interfere with the selection of behaviorally relevant information. Many studies have shown that that distraction can be minimized via top-down control [3-5], but the cognitive and neural mechanisms giving rise to this control over distraction remain uncertain and vigorously debated [6-8]. Bridging neurophysiology to electrophysiology, we simultaneously recorded neurons in prefrontal cortex and event-related potentials (ERPs) over extrastriate visual cortex to track the processing of salient distractors during a visual search task. Critically, we observed robust suppression of salient distractor representations in both cortical areas, with suppression arising in prefrontal cortex before being manifest in the ERP signal over extrastriate cortex. Furthermore, only prefrontal neurons that participated in selecting the task-relevant target also showed suppression of the task-irrelevant distractor. This suggests a common prefrontal mechanism for target selection and distractor suppression, with input from prefrontal cortex being responsible for both selecting task-relevant and suppressing task-irrelevant information in sensory cortex. Taken together, our results resolve a long-standing debate over the mechanisms that prevent distraction, and provide the first evidence directly linking suppressed neural firing in prefrontal cortex with surface ERP measures of distractor suppression.