PT  - JOURNAL ARTICLE
AU  - Dominik Oliver
AU  - Annette M. Taberner
AU  - Henrike Thurm
AU  - Matthias Sausbier
AU  - Claudia Arntz
AU  - Peter Ruth
AU  - Bernd Fakler
AU  - M. Charles Liberman
TI  - The Role of BK<sub>Ca</sub> Channels in Electrical Signal Encoding in the Mammalian Auditory Periphery
AID  - 10.1523/JNEUROSCI.1047-06.2006
DP  - 2006 Jun 07
TA  - The Journal of Neuroscience
PG  - 6181--6189
VI  - 26
IP  - 23
4099  - http://www.jneurosci.org/content/26/23/6181.short
4100  - http://www.jneurosci.org/content/26/23/6181.full
SO  - J. Neurosci.2006 Jun 07; 26
AB  - Large-conductance voltage- and Ca2+-activated K+ channels (BKCa) are involved in shaping spiking patterns in many neurons. Less is known about their role in mammalian inner hair cells (IHCs), mechanosensory cells with unusually large BKCa currents. These currents may be involved in shaping the receptor potential, implying crucial importance for the properties of afferent auditory signals. We addressed the function of BKCa by recording sound-induced responses of afferent auditory nerve (AN) fibers from mice with a targeted deletion of the pore-forming α-subunit of BKCa (BKα−/−) and comparing these with voltage responses of current-clamped IHCs. BKCa-mediated currents in IHCs were selectively abolished in BKα−/−, whereas cochlear physiology was essentially normal with respect to cochlear sensitivity and frequency tuning. BKα−/− AN fibers showed deteriorated precision of spike timing, measured as an increased variance of first spike latency in response to tone bursts. This impairment could be explained by a slowed voltage response in the presynaptic IHC resulting from the reduced K+ conductance in the absence of BKCa. Maximum spike rates of AN fibers were reduced nearly twofold in BKα−/−, contrasting with increased voltage responses of IHCs. In addition to presynaptic changes, which may be secondary to a modest depolarization of BKα−/− IHCs, this reduction in AN rates suggests a role of BKCa in postsynaptic AN neurons, which was supported by increased refractory periods. In summary, our results indicate an essential role of IHC BKCa channels for precise timing of high-frequency cochlear signaling as well as a function of BKCa in the primary afferent neuron.