[Functional refinement of bushy cells in the anterior ventral cochlear nucleus precedes hearing onset in neonatal rats].

OBJECTIVE To investigate the development of the electrophysiological property of bushy cells in the anterior ventral cochlear nucleus (AVCN) of neonatal Sprague Dawley (SD) rats. METHODS The development of action potential and spontaneous miniature excitatory postsynaptic currents (mEPSCs) in AVCN bushy cells were investigated by whole-cell patch-clamp technique in SD rats during the postnatal days 5-21 (P5-21). The half band width of the action potential (AP), 10%-90% risetime and decay tau of the mEPSCs were analyzed. RESULTS The AP of the bushy cells became faster with age from P5 to P21 and stopped changing around the period of hearing onset, as evidenced by the alteration of half band width of the AP. The time accuracy of mEPSCs of the bushy cells also increased with age and stabilized around hearing onset as shown by briefer 10%-90% rise time and decay tau of mEPSCs in P14/P21 than in P7. CONCLUSION The functional refinement of the bushy cells in the AVCN precedes hearing onset in neonatal rats.