Attentional control guides the strategic filtering of potential distraction as revealed by behavior and Fmri

When dealing with significant sensory stimuli, performance can be hampered by distracting events. Attention mechanisms lessen such negative effects, enabling selection of relevant information while blocking potential distraction. Recent work shows that preventing the negative impact of forthcoming distraction is actively achieved by attentional selection processes. Thus, I hypothesize that the engagement of a distraction-filtering mechanism to counteract distraction, although indisputably beneficial when distraction occurs, also taxes cognitive-brain systems when distraction is expected but does not occur, leading to performance costs. In my thesis, I seek the behavioral and brain signature of a mechanism for the filtering of potential distraction within and between sensory modalities. I show that, when potential distraction is foreseen in a stimulus-processing context, a cognitive mechanism is engaged for limiting negative impact of irrelevant stimuli on behavioral performance, yet its engagement is resource-demanding and thus incurs a performance cost when distraction does not occur. This cost consists of slower response times to a simple sensory stimulus when presented alone but in a potentially-distracting context, as compared to the same stimulus presented in a completely distraction-free context. This cost generalizes across different target and distracters sensory modalities, such as touch, vision and audition, and to both space-based and feature-based attention tasks. The activation of the filtering mechanism relies on both strategic and reactive processes, as shown by its dynamic dependence on probabilistic and cross-trial contingencies. Probability of conflict substantially modulates the magnitude of the filtering cost, which results larger in contexts where the probability of experiencing conflict is high. Crucially, across participants, the observed strategic cost is inversely related to the interference exerted by a distracter on distracter-present trials. The strategic filtering mechanism is predominantly adopted as a longer-term, sustained, cognitive set throughout an extended time period. Its activation is associated with sustained brain activity in prefrontal areas and in the frontoparietal attentional network. Sustained brain activity in prefrontal areas correlates across participants with the filtering cost, thus confirming a close relationship between this sustained activation and the observed behavioral cost. I also show that the recruitment of the distraction filtering mechanism in a potentially distracting context guides attention and behavior through different top-down modulations. In fact, when potential distraction is foreseen, the activation of a filtering mechanism promotes both the attenuation of sensory representation of distracting stimuli in extrastriate visual cortex and the prevention of involuntary activations of conflict-driven motor responses in the premotor cortex. These results attest to the existence of a system for the monitoring and filtering of potential distraction in the human brain that likely reflects a general mechanism of cognitive-attentional control.