Superior colliculus encodes visual saliency during smooth pursuit eye movements.

Area of Science:

• Neuroscience
• Visual Attention
• Oculomotor Control

Background:

• The saliency map is crucial for visual attention models and theories, with neurobiological support from various brain regions.
• Visual saliency computation is established during fixation, but its role during smooth pursuit eye movements remains unclear.
• The superior colliculus (SC) is a midbrain structure implicated in attention and gaze control.

Purpose of the Study:

• To investigate extrafoveal saliency coding in the superior colliculus (SC) during smooth pursuit eye movements.
• To determine if the SC maintains its role as a saliency map when tracking moving stimuli.

Main Methods:

• Electrophysiological recordings from superior colliculus (SC) neurons in awake subjects.
• Presentation of peripheral visual stimuli during smooth pursuit eye movements.
• Analysis of neuronal responses in superficial visual and intermediate saccade-related layers of the SC.

Main Results:

• Neurons in the superficial visual layers of the SC demonstrated a strong representation of peripheral saliency during smooth pursuit.
• Visuomotor neurons in the intermediate saccade-related layers showed limited saliency representation, despite visual responsiveness.
• The SC's role in monitoring peripheral vision extends to dynamic conditions involving smooth pursuit.

Conclusions:

• The superficial layers of the SC act as a saliency map, effectively coding peripheral visual information during smooth pursuit.
• The intermediate saccade-related layers of the SC are less involved in saliency coding during smooth pursuit compared to superficial layers.
• These findings confirm and expand the SC's established function in monitoring peripheral vision during both static and dynamic gaze behaviors.