Glutamate and aspartate mimic the afferent transmitter in the cochlea.

Glutamate (50 mM) and aspartate (50 mM) applied intracochlearly increase the spontaneous activity of ganglion cells of the auditory nerve. This activity may account for the decreased magnitude of the compound action potential observed with these substances in previous studies, and also may be additional evidence that these substances have a role in synaptic transmission between the hair cells and primary auditory afferent nerve cells.