The mouse superior colliculus promotes competing actions independently of sensory inputs

The superior colliculus (SC) is thought to integrate visual and auditory signals and help select actions, but it is unknown if and how these capabilities jointly contribute to behavior. Here, we show that the SC promotes competing actions independently of stimuli. We trained mice to locate an audiovisual stimulus on their left or right, and found that auditory, visual, and action-related signals are largely carried by separate SC neurons in different layers. Unilateral SC inactivation did not affect sensory sensitivity but reduced contralateral actions in favor of inaction. Bilateral inactivation restored left-right balance. A simple 3-option logistic classification model captured the results, with prefrontal cortex summing sensory signals from sensory cortices and the two sides of SC contributing stimulus-independent signals promoting both eligible actions. The role of SC in perceptual decisions is thus to promote competing actions independently of sensory inputs. HighlightsO_LIMouse choices in a left-right audiovisual task obey a 3-option logistic classifier C_LIO_LIThe superior colliculus (SC) encodes vision, audition, and action independently C_LIO_LIThe SC provides stimulus-independent pressures favoring all competing actions C_LIO_LISensory stimuli affect the competition through sensory and prefrontal cortex C_LI