Superior colliculus encodes visual saliency during smooth pursuit eye movements

The saliency map has played a long‐standing role in models and theories of visual attention, and it is now supported by neurobiological evidence from several cortical and subcortical brain areas. While visual saliency is computed during moments of active fixation, it is not known whether the same is true while engaged in smooth pursuit of a moving stimulus, which is very common in real‐world vision. Here, we examined extrafoveal saliency coding in the superior colliculus, a midbrain area associated with attention and gaze, during smooth pursuit eye movements. We found that SC neurons from the superficial visual layers showed a robust representation of peripheral saliency evoked by a conspicuous stimulus embedded in a wide‐field array of goal‐irrelevant stimuli. In contrast, visuomotor neurons from the intermediate saccade‐related layers showed a poor saliency representation, even though most of these neurons were visually responsive during smooth pursuit. These results confirm and extend previous findings that place the SCs in a unique role as a saliency map that monitors peripheral vision during foveation of stationary and now moving objects. We examined the role of the superior colliculus, a midbrain area closely associated with gaze/attention, in extrafoveal saliency processing during smooth pursuit eye movements. SC neurons from the superficial visual layers showed a gradual increase then decrease in response to a salient, yet goal‐irrelevant, oddball‐stimulus as the receptive field was drawn over it by virtue of a pursuit movement that tracked a separate stimulus. These results extend previous findings showing that SCs functions qualitatively similar during foveation of stationary or moving stimuli, and provide another layer of validation for models and theories of the saliency map.