Dendritic Calcium Channels and Their Activation by Synaptic Signals in Auditory Coincidence Detector Neurons
Dendritic Calcium Channels and Their Activation by Synaptic Signals in Auditory Coincidence Detector Neurons
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DOI：
10.1152/jn.90513.2008
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发表时间：
2009-08-01
影响因子：
2.5
通讯作者：
Trussell, Laurence O.
中科院分区：
文献类型：
--
作者：
Blackmer, Trillium;Kuo, Sidney P.;Trussell, Laurence O.
刘国强，郭国强，刘国强，刘国强。听觉重合检测神经元树突钙通道及其突触信号的激活。[J]中国生物医学工程学报，2009,31(2):518 - 526。首次发表于2009年6月24日；doi: 10.1152 / jn.90513.2008。鸟类层状核（NL）通过检测双耳信号的重合来编码低频声源的方位位置。准确的巧合检测需要精确的发育调节精细的、沥青状树突的长度，这是NL神经元的特征。这种调节被认为是由局部的、突触介导的树突信号（如Ca2+）驱动的。我们通过膜片钳和离子成像实验检测了胚胎鸡层状核切片中的Ca2+信号。位于NL的神经元的电压钳记录显示存在两种类型的大Ca2+电流，一种是低压激活的，类似哺乳动物t型通道的Ni2+敏感通道，一种是高压激活的，缓慢失活的Cd2+敏感通道。双光子Ca2+成像显示两种通道类型都集中在树突上，甚至在它们的远端尖端。通过突触或体细胞电流注射触发的单动作电位立即升高整个细胞的Ca2+。阈下突触活动触发的Ca2+信号高度局域化。因此，当电活动超过阈值时，Ca2+通道确保所有树突中的Ca2+上升，即使是那些突触不活跃的树突。
Blackmer T, Kuo SP, Bender KJ, Apostolides PF, Trussell LO. Dendritic calcium channels and their activation by synaptic signals in auditory coincidence detector neurons. J Neurophysiol 102: 1218-1226, 2009. First published June 24, 2009; doi:10.1152/jn.90513.2008. The avian nucleus laminaris (NL) encodes the azimuthal location of low-frequency sound sources by detecting the coincidence of binaural signals. Accurate coincidence detection requires precise developmental regulation of the lengths of the fine, bitufted dendrites that characterize neurons in NL. Such regulation has been suggested to be driven by local, synaptically mediated, dendritic signals such as Ca2+. We examined Ca2+ signaling through patch clamp and ion imaging experiments in slices containing nucleus laminaris from embryonic chicks. Voltage-clamp recordings of neurons located in the NL showed the presence of large Ca2+ currents of two types, a low voltage-activated, fast inactivating Ni2+ sensitive channel resembling mammalian T-type channels, and a high voltage-activated, slowly inactivating Cd2+ sensitive channel. Two-photon Ca2+ imaging showed that both channel types were concentrated on dendrites, even at their distal tips. Single action potentials triggered synaptically or by somatic current injection immediately elevated Ca2+ throughout the entire cell. Ca2+ signals triggered by subthreshold synaptic activity were highly localized. Thus when electrical activity is suprathreshold, Ca2+ channels ensure that Ca2+ rises in all dendrites, even those that are synaptically inactive.