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

The location of visual stimuli influences the actions animals select, reflecting the distinct ecological and behavioral significance of the upper and lower visual fields. In mice, the superior colliculus transforms visual information into defensive and approach behaviors, with its superficial layers containing genetically defined cell types with distinct projections. Whether these circuits are repeated across visual space or are specialized by visual-field position remains unclear. Dual-color rabies tracing demonstrated that wide- and narrow-field neurons receive input from a largely shared set of brain regions, whereas upper- and lower-field domains sample these inputs differently. Some regions preferentially innervate one visual field domain; others contain spatially segregated neurons innervating each domain. Multiplexed analysis of projections by sequencing (MAPseq) showed that most superficial collicular neurons project to a single downstream target, but target probabilities differ between upper- and lower-field populations. Together, these findings identify visual-field position as a major organizing principle of input and output connectivity in the superficial superior colliculus.