GABA co-release guides the functional maturation of glycinergic synapses in an auditory sound localization circuit

Glycinergic neurons in the brainstem and spinal cord often co-release GABA during development, but the role of this co-release in circuit refinement or synapse maturation remains poorly understood. This study found that disruption of developmental GABA co-release at the MNTB-LSO synapse, a key part of the sound localization circuit, did not affect topographic refinement by synapse elimination or strengthening. However, impaired GABA co-release prevented synapses from developing the characteristic features that enable the high-fidelity, temporally accurate transmission required for sound localization. This highlights a critical role for developmental GABA co-release in shaping the specialized functional architecture of glycinergic synapses critical for binaural processing and sound localization.