An inhibitory brainstem pathway reduces visual detection during background motion.

Moving backgrounds profoundly impact object perception, a crucial process for parsing complex visual scenes. This motion-induced modulation has traditionally been attributed to visual cortical circuits. However, recent evidence that brainstem activity is also influenced by background motion raises the intriguing question of whether subcortical circuits play a role in this perceptual phenomenon. Here, we demonstrate that inhibitory projections from mouse nucleus of the optic tract (NOT)-a brainstem structure mediating reflexive behaviors-impair superior colliculus (SC)-dependent visual detection during background motion. Specifically, the inhibitory NOT projections to SC are selectively activated by global, but not local, background motion to suppress SC activity. Remarkably, silencing this NOT-SC pathway relieves the suppression of SC activity in such motional context and alleviates the motion-induced impairments in visual detection. Our findings reveal that motion-sensitive brainstem circuits suppress subcortical processing to shape visual perception, underscoring the underappreciated role of the brainstem in visual cognition.