2002b, Interaction of excitation and inhibition in anteroventral cochlear nucleus neurons that receive large endbulb synaptic endings

Spherical bushy cells (SBCs) of the anteroventral cochlear nu-cleus (AVCN) receive their main excitatory input from auditory nerve fibers (ANFs) through large synapses, endbulbs of Held. These cells are also the target of inhibitory inputs whose func-tion is not well understood. The present study examines the role of inhibition in the encoding of low-frequency sounds in the gerbil’s AVCN. The presynaptic action potentials of endbulb terminals and postsynaptic action potentials of SBCs were monitored simultaneously in extracellular single-unit recordings in vivo. An input–output analysis of presynaptic and postsyn-aptic activity was performed for both spontaneous and acous-tically driven activity. Two-tone stimulation and neuropharma-cological experiments allowed the effects of neuronal inhibition and cochlear suppression on SBC activity to be distinguished. Ninety-one percent of SBCs showed significant neurona