Deconstructing Reorienting of Attention: Cue Predictiveness Modulates the Inhibition of the No-target Side and the Hemispheric Distribution of the P1 Response to Invalid Targets.

Orienting of attention produces a "sensory gain" in the processing of visual targets at attended locations and an increase in the amplitude of target-related P1 and N1 ERPs. P1 marks gain reduction at unattended locations; N1 marks gain enhancement at attended ones. Lateral targets that are preceded by valid cues also evoke a larger P1 over the hemisphere contralateral to the no-target side, which reflects inhibition of this side of space [Slagter, H. A., Prinssen, S., Reteig, L. C., & Mazaheri, A. Facilitation and inhibition in attention: Functional dissociation of pre-stimulus alpha activity, P1, and N1 components. Neuroimage , 125 , 25-35, 2016]. To clarify the relationships among cue predictiveness, sensory gain, and the inhibitory P1 response, we compared cue- and target-related ERPs among valid, neutral, and invalid trials with predictive (80% valid/20% invalid) or nonpredictive (50% valid/50% invalid) directional cues. Preparatory facilitation over the visual cortex contralateral to the cued side of space (lateral directing attention positivity component) was reduced during nonpredictive cueing. With predictive cues, the target-related inhibitory P1 was larger over the hemisphere contralateral to the no-target side not only in response to valid but also in response to neutral and invalid targets: This result highlights a default inhibitory hemispheric asymmetry that is independent from cued orienting of attention. With nonpredictive cues, valid targets reduced the amplitude of the inhibitory P1 over the hemisphere contralateral to the no-target side whereas invalid targets enhanced the amplitude of the same inhibitory component. Enhanced inhibition was matched with speeded reorienting to invalid targets and drop in attentional costs. These findings show that reorienting of attention is modulated by the combination of cue-related facilitatory and target-related inhibitory activity.