A Diencephalic Dopamine Source Provides Input to the Superior Colliculus, where D1 and D2 Receptors Segregate to Distinct Functional Zones

•RNA-seq describes dopamine-related gene expression in the superior colliculus (SC)•D1+ and D2+ neurons segregate to functionally distinct SC layers•D1+ and D2+ neurons in the SC differentially express the inhibitory marker VGAT•Retrograde tracing points to A13 as the source of dopamine to the SC•Patch-clamp analysis suggests functional consequences of SC dopamine

SummaryModulation of neural responses is frequently observed in the superior colliculus (SC), a retinorecipient midbrain structure that controls orienting and the localization of attention. Although behavioral contingencies that influence SC responses are well documented, the neural pathways and molecular mechanisms responsible for this modulation are not completely understood. Here, we illustrate a dopaminergic system that strongly impacts neural responses in the SC. After using RNA sequencing (RNA-seq) to detail the transcriptome of dopamine-related genes in the SC, we show that D1 receptors are enriched in the superficial visual SC, while D2 receptors segregate to the intermediate multimodal/motor SC. Retrograde injections into the SC consistently label A13, a small dopamine cell group located in the zona incerta. We surmise that A13 mimics dopaminergic effects that we observed in SC slices, which suggests that dopamine in the SC may reduce the tendency of an animal to orient or attend to salient stimuli.

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