TY - JOUR T1 - Tonotopic Specialization of Auditory Coincidence Detection in Nucleus Laminaris of the Chick JF - The Journal of Neuroscience JO - J. Neurosci. SP - 1924 LP - 1934 DO - 10.1523/JNEUROSCI.4428-04.2005 VL - 25 IS - 8 AU - Hiroshi Kuba AU - Rei Yamada AU - Iwao Fukui AU - Harunori Ohmori Y1 - 2005/02/23 UR - http://www.jneurosci.org/content/25/8/1924.abstract N2 - The interaural time difference (ITD) is a cue for localizing a sound source along the horizontal plane and is first determined in the nucleus laminaris (NL) in birds. Neurons in NL are tonotopically organized, such that ITDs are processed separately at each characteristic frequency (CF). Here, we investigated the excitability and coincidence detection of neurons along the tonotopic axis in NL, using a chick brainstem slice preparation. Systematic changes with CF were observed in morphological and electrophysiological properties of NL neurons. These properties included the length of dendrites, the input capacitance, the conductance of hyperpolarization-activated current, and the EPSC time course. In contrast to these gradients, the conductance of low-threshold K+ current and the expression of Kv1.2 channel protein were maximal in the central (middle-CF) region of NL. As a result, the middle-CF neuron had the smallest input resistance and membrane time constant, and consequently the fastest EPSP, and exhibited the most accurate coincidence detection. The specialization of middle-CF neurons as coincidence detectors may account for the high resolution of sound-source localization in the middle-frequency range observed in avians. ER -