Visual field position shapes input sampling and output routing in the superior colliculus

Animals use the location of visual stimuli to select appropriate actions, and the upper and lower visual field often carry different ecological and behavioral meaning. In mice, the superior colliculus is a key cen-tral hub that transforms visual input into orienting, defensive, and approach behaviors. Its superficial layers receive retinotopically organized input from the retina and contain genetically defined cell types with distinct downstream projections, including wide-field neurons that project to the lateral posterior thalamus and narrow-field neurons that target the parabigeminal nucleus and deeper collicular layers. These fea-tures raise the question of whether circuits of the superior colliculus are repeated across visual space or ex-hibit visual-field-dependent specializations. Here, we show that the mouse superficial superior colliculus contains visual-field-dependent circuit modules. Dual-color rabies tracing revealed that wide-field and nar-row-field neurons receive input from a largely shared set of brain regions, whereas upper- and lower-field domains differ in how they sample those inputs. Some source regions preferentially innervate one visual-field domain, producing biased regional input strength, while others contain topographically segregated pro-jecting neurons that target upper- or lower-field domains. MAPseq showed that most superficial collicular neurons project to single downstream targets, with upper- and lower-field populations differing in target probability. Two-photon calcium imaging further showed that wide-field neurons in upper- and lower-field domains differ in stimulus selectivity. Together, these findings reveal a visual-field-dependent wiring logic that biases how the superior colliculus samples inputs and routes signals to downstream pathways.