Two complimentary codes in the superior colliculus differentiate external from self-generated tactile cues

During tactile localization, animals must differentiate stimuli caused by their own volitional movement from externally generated object motion. To determine a neural basis for this ability, we examined the mouse superior colliculus (SC), which contains multiple egocentric maps of sensorimotor space. By placing mice in a whisker-guided virtual reality, we discovered a rapidly adapting neural response that strongly preferred external over self-generated changes in tactile space. This transient response only emerged when external motion gained contact with a whisker, arguing that stimulus adaptation was whisker-specific. The accumulation of sensory evidence through active sensing and repetitions in external motion controlled the size of the transient response. Population-level firing rates among transiently responsive neurons accurately encoded the direction of external motion. These data reveal that stimulus-specific adaptation together with accumulating sensorimotor predictions in SC neurons enhance the localization of unexpected motion in the environment.