TY - JOUR T1 - Hyperpolarization-Activated Cyclic Nucleotide-Gated Cation Channels Regulate Auditory Coincidence Detection in Nucleus Laminaris of the Chick JF - The Journal of Neuroscience JO - J. Neurosci. SP - 8867 LP - 8877 DO - 10.1523/JNEUROSCI.2541-05.2005 VL - 25 IS - 39 AU - Rei Yamada AU - Hiroshi Kuba AU - Takahiro M. Ishii AU - Harunori Ohmori Y1 - 2005/09/28 UR - http://www.jneurosci.org/content/25/39/8867.abstract N2 - Coincidence detection of bilateral acoustic signals in nucleus laminaris (NL) is the first step in azimuthal sound source localization in birds. Here, we demonstrate graded expression of hyperpolarization-activated cyclic nucleotide-gated (HCN) cation channels along the tonotopic axis of NL and its role in the regulation of coincidence detection. Expression of HCN1 and HCN2, but not HCN3 or HCN4, was detected in NL. Based on measurement of both subtype mRNA and protein, HCN1 varied along the tonotopic axis and was minimal in high-characteristic frequency (CF) neurons. In contrast, HCN2 was evenly distributed. The resting conductance was larger and the steady-state activation curve of Ih was more positive in neurons of middle to low CF than those of high CF, consistent with the predominance of HCN1 channels in these neurons. Application of 8-Br-cAMP or noradrenaline generated a depolarizing shift of the Ih voltage activation curve. This shift was larger in neurons of high CF than in those of middle CF. The shift in the activation voltage of Ih depolarized the resting membrane, accelerated the EPSP time course, and significantly improved the coincidence detection in neurons of high CF, suggesting that Ih may improve the localization of sound sources. ER -