Locomotion-induced neural activity independent of auditory feedback in the mouse inferior colliculus

Accumulating evidence indicates that the auditory pathway integrates movement-related signals with auditory input, yet the precise sources and mechanisms of this integration across various processing levels are incompletely understood. The inferior colliculus (IC), a major midbrain hub in the auditory pathway, shows widespread modulation of neural activity during locomotion, indicating that auditory neurons at this level are sensitive to ongoing movement. However, in hearing animals, it has been challenging to dissociate auditory feedback from other motor-related signals. In this study, to isolate non-auditory contributions, we recorded IC neural activity during locomotion in deafened mice, thereby eliminating all auditory feedback through both air and bone conduction. Even in the absence of auditory input, IC neurons exhibited robust, bidirectional modulation during locomotion. Timing analysis using electromyography revealed both predictive and feedback components relative to locomotion onset. Furthermore, the timing and direction of modulation varied considerably across different locomotion bouts, suggesting convergence of multiple non-auditory inputs. These findings demonstrate that non-auditory, movement-related signals significantly shape auditory midbrain activity through both predictive and feedback mechanisms.