Neural correlates of proactive and reactive inhibition of saccadic eye movements
Although research on goal-directed, proactive inhibitory control (IC) and stimulus-driven, reactive IC is growing, no previous study has compared proactive IC in conditions of uncertainty with regard to upcoming inhibition to conditions of certain upcoming IC. Therefore, we investigated effects of certainty and uncertainty on behavior and blood oxygen level dependent (BOLD) signal in proactive and reactive IC. In two studies, healthy adults performed saccadic go/no-go and prosaccade/antisaccade tasks. The certainty manipulation had a highly significant behavioral effect in both studies, with inhibitory control being more successful under certain than uncertain conditions on both tasks (p ≤ 0.001). Saccadic go responses were significantly less efficient under conditions of uncertainty than certain responding (p < 0.001). Event-related functional magnetic resonance imaging (fMRI) (one study) revealed a dissociation of certainty- and uncertainty-related proactive inhibitory neural correlates in the go/no-go task, with lateral and medial prefrontal and occipital cortex showing stronger deactivations during uncertainty than during certain upcoming inhibition, and lateral parietal cortex being activated more strongly during certain upcoming inhibition than uncertainty or certain upcoming responding. In the antisaccade task, proactive BOLD effects arose due to stronger deactivations in uncertain response conditions of both tasks and before certain prosaccades than antisaccades. Reactive inhibition-related BOLD increases occurred in inferior parietal cortex and supramarginal gyrus (SMG) in the go/no-go task only. Proactive IC may imply focusing attention on the external environment for encoding salient or alerting events as well as inhibitory mechanisms that reduce potentially distracting neural processes. SMG and inferior parietal cortex may play an important role in both proactive and reactive IC of saccades.
KeywordsProactive inhibition Eye movements Antisaccade task Go/no-go task Event-related fMRI Reactive inhibition Go/no-go Antisaccade Eye tracking fMRI
The authors would like to thank Bertalan Polner (Budapest University of Technology and Economics, Budapest) for his valuable contribution to a pilot of this study.
This study was funded by the DFG (Et 31/2–1).
Compliance with ethical standards
The study was approved by the ethics committee of the Department of Psychology at the University of Bonn and conducted in conformity with the Declaration of Helsinki.
Conflict of interest
The authors declare no conflict of interest.
All participants gave informed consent before participating in the study.
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