Cognitive control of saccadic selection and inhibition from within the core cortical saccadic network

Abstract

The ability to select the task-relevant stimulus for a saccadic eye movement, while inhibiting saccades to task-irrelevant stimuli, is crucial for active vision. Here, we present a novel saccade-contingent behavioral paradigm and investigate the neural basis of the central cognitive functions underpinning such behavior, saccade selection, saccade inhibition, and saccadic choice, in female and male human participants. The paradigm allows for exceptionally well-matched contrasts, with task demands formalized with stochastic accumulation-to-threshold models. Using fMRI, we replicated the core cortical eye-movement network for saccade generation (frontal eye fields, posterior parietal cortex, and higher-level visual areas). However, in contrast to previously published tasks, saccadic selection and inhibition recruited only this core network. Brain-behavior analyses further showed that inhibition efficiency may be underpinned by white-matter integrity of tracts between key saccade-generating regions, and that inhibition efficiency is associated with right inferior frontal gyrus engagement, potentially implementing general-purpose inhibition. The core network, however, was insufficient for saccadic choice, which recruited anterior regions commonly attributed to saccadic action selection, including dorsolateral prefrontal cortex and anterior cingulate cortex. Jointly, the results indicate that extra-saccadic activity observed for free choice, and in previously published tasks probing saccadic control, is likely due to increased load on higher-level cognitive processes, and not saccadic selection per se, which is achieved within the canonical cortical eye movement network.