A distributed network of cortical and subcortical brain areas controls our oculomotor behavior. This network includes the superior colliculus (SC), which coordinates an ancient visual grasp reflex via outputs that ramify widely within the brainstem and spinal cord, accessing saccadic and other premotor and autonomic circuits. In this Review, we discuss recent results correlating subliminal SC activity in the absence of saccades with diverse components of the visual grasp reflex, including neck and limb muscle recruitment, pupil dilation, andmicrosaccade propensity. Such subtle manifestations of covert orienting are accessible in the motor periphery and may provide the next generation of oculomotor biomarkers in health and disease. Corneil and Munoz discuss the role of the superior colliculus (SC) during orienting. Because of differences in how SC outputs are processed, neck and limb muscle recruitment, pupil dilation, and microsaccades reflect covert oculomotor processes in the absence of saccades.
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