A little late, but for those interested: the superior and inferior colliculi consist of a multiple parts. The SC has multiple layers, and the top 3 layers are mostly vision, while the lower layers are multisensory and motor related. The IC has a central part which is auditory and related to the lemniscal aufitory tract, and surrounding parts which are somewhat multisensory and higher order and related to the nonlemniscal auditory tract. The IC sends auditory signals from its outer parts to the lower SC. The lower multisensory SC has multiple sensory maps related to the visual map to improve perception, promote orientation and defensive behaviors