(A) ChAT-Cre/tdTomato-positive neurons in the LSO and VNTB of the superior olivary complex co-labeled with anti-ChAT antibody (B) confirming they are cholinergic neurons (C). ChAT-Cre/tdTomato-positive neurons in the ipsilateral LSO (D) and contralateral VNTB (E) were retrogradely labeled by cochlear CTB injections. (F) Contralateral to cochlear CTB injections, 66.1% of ChAT-Cre/tdTomato-positive VNTB neurons were labeled. In ipsilateral VNTB, 28.9% of ChAT-Cre/tdTomato=positive neurons were labeled (N = 3 mice, 205 cells). Abbreviations: LNTB, lateral nucleus of the trapezoid body; LSO, lateral superior olive; VNTB, ventral nucleus of the trapezoid body; CTB, cholera toxin subunit B.