Endogenous and exogenous attentional interplay through mixed prefrontal cortex resources

Spatial attention can be either involuntarily drawn to salient, unexpected events (exogenous attention) or voluntarily directed (endogenous attention). Evidence suggests a distinction between the two forms of attention, with only endogenous attention believed to operate independently of the motor system. We investigated the role of the lateral prefrontal cortex (lPFC) in this relationship, using a task that spatially dissociated attention from motor goals in two monkeys. Our findings show that some lPFC units exhibit highly dynamic encoding, flexibly representing either the attended location or the motor target, simultaneously or at different time points. We show that these neural resources are crucial in exogenous attention. However, they can also be recruited by endogenous deployment of attention, resulting in two main effects: (1) a reduction in interference between the motor and attention systems; and (2) modulation of exogenous shifts for attentional capture, with stronger shifts occurring when endogenous attention is weak. Overall, our results suggest that exogenous attention helps refine attentional control by rapidly mobilizing neural units shared between the attention and motor systems, even during endogenous attention deployment. We refer to these units as overlapping resources, as they enable a dynamic balance between internal goals and external demands, similar to adaptive buffer systems.