Abstract
The Calyx of Held (CoH) synapse is the largest synapse in mammals. It is located in the medial nucleus of the trapezoid body (MNTB) and forms part of the auditory pathway. Modest GABAergic signaling is present in the CoH before hearing onset, when glutamatergic transmission predominates. In mice, after postnatal day 12, the absolute strength of glycinergic transmission increases markedly, while GABAergic signaling remains constant.