Probing the Neural Mechanisms for Distractor Filtering and Their History-Contingent Modulation by Means of TMS

Abstract

In visual search, the presence of a salient, yet task-irrelevant, distractor in the stimulus array interferes with target selection and slows down performance. Neuroimaging data point to a key role of the frontoparietal dorsal attention network in dealing with visual distractors; however, the respective roles of different nodes within the network and their hemispheric specialization are still unresolved. Here, we used transcranial magnetic stimulation (TMS) to evaluate the causal role of two key regions of the dorsal attention network in resisting attentional capture by a salient singleton distractor: the frontal eye field (FEF) and the cortex within the intraparietal sulcus (IPS). The task of the participants (male/female human volunteers) was to discriminate the pointing direction of a target arrow while ignoring a task-irrelevant salient distractor. Immediately after stimulus onset, triple-pulse 10 Hz TMS was delivered either to IPS or FEF on either side of the brain. Results indicated that TMS over the right FEF significantly reduced the behavioral cost engendered by the salient distractor relative to left FEF stimulation. No such effect was obtained with stimulation of IPS on either side of brain. Interestingly, this FEF-dependent reduction in distractor interference interacted with the contingent trial history, being maximal when no distractor was present on the previous trial relative to when there was one. Our results provide direct causal evidence that the right FEF houses key mechanisms for distractor filtering, pointing to a pivotal role of the frontal cortex of the right hemisphere in limiting interference from an irrelevant but attention-grabbing stimulus.

Commentary: Probing the Neural Mechanisms for Distractor Filtering and Their History-Contingent Modulation by Means of TMS

“…A second explanation is that the stimulation impaired attention biasing, or pop-out detection, processes by disrupting neural circuits responsible for attentional capture from salient visual features. Lega et al (2019) favor the enhancement of distractor filtering explanation and rule out the disruption of attentional capture explanation, but this interpretation warrants further discussion. Lega et al (2019) argued that if stimulation of the right FEF disrupted attentional capture by impairing saliency computation, performance on distractor-absent trials should also be impacted.…”

“…Lega et al (2019) favor the enhancement of distractor filtering explanation and rule out the disruption of attentional capture explanation, but this interpretation warrants further discussion. Lega et al (2019) argued that if stimulation of the right FEF disrupted attentional capture by impairing saliency computation, performance on distractor-absent trials should also be impacted. Specifically, the authors suggest that target detection in and of itself also involves some saliency computation and that if this process was disrupted, RT even on distractor-absent trials should be slowed by TMS over the right FEF relative to the sham location.…”

“…Probing the Neural Mechanisms for Distractor Filtering and Their History-Contingent Modulation by Means of TMS by Lega, C., Ferrante, O., Marini, F., Santandrea, E., Cattaneo, L., and Chelazzi, L. (2019). J.…”

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The ability to suppress irrelevant but attention grabbing stimuli in our environment is critical for maintaining goal-directed control during many daily activities, such as avoiding junk foods while dieting or ignoring distractions while driving. Although we know much about the properties of environmental cues that make them susceptible to attentional capture (e.g., bright lights, loud sounds, fast movements), we know far less about how to disengage from such distractions, particularly the neural mechanisms involved in these processes.In a recent paper by Lega et al (2019), the authors examined whether non-invasive brain stimulation, using transcranial magnetic stimulation (TMS), could be used to modulate distractor filtering when applied over the dorsal frontoparietal attentional networks, specifically the frontal eye field (FEF) and the intraparietal sulcus (IPS). The authors used a visual search task in which participants had to identify a target within a four-item array.

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“…In a recent paper by Lega et al (2019), the authors examined whether non-invasive brain stimulation, using transcranial magnetic stimulation (TMS), could be used to modulate distractor filtering when applied over the dorsal frontoparietal attentional networks, specifically the frontal eye field (FEF) and the intraparietal sulcus (IPS). The authors used a visual search task in which participants had to identify a target within a four-item array.…”