Multiple groups of neurons in the superior colliculus convert value signals into saccadic vigor

Eye movements toward high-valued objects are executed with greater vigor. To test how neurons in the superior colliculus (SC), a subcortical structure that controls these movements, are modulated by value, we recorded four SC neuron subtypes while monkeys made saccades to objects previously associated with high or low reward volumes. High-value objects elicited greater activity in three neuron subtypes (visual, visuomotor, motor). Using a bootstrapping method, we identified three distinct activity phases: early visual response (E_VIS), late visual response (L_VIS), and pre-saccadic (Pre_SAC) motor response. Value was positively correlated with activity in the L_VIS and Pre_SAC phases, but not in the E_VIS phase, suggesting that value modulates visual and motor stages of visuomotor transformation. Additionally, we discovered a class of tonically active neurons that decrease their activity upon object onset, and remain inhibited till the end of the saccade, potentially enhancing saccade execution by disinhibiting interactions among other SC neurons.