Representation of auditory signals in the M-cell: role of electrical synapses.
Representation of auditory signals in the M-cell: role of electrical synapses.
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M 细胞中听觉信号的表示：电突触的作用。
DOI：
10.1152/jn.01287.2005
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Preuss,T
中科院分区：
文献类型：
--
作者：
Szabo,TM;Weiss,SA;Faber,DS;Preuss,T
硬骨鱼Mauthner（M-）细胞介导声音诱发的逃避行为。听觉输入的一个主要成分是由后VIII神经的大的有髓神经末梢传递的。奇怪的是，虽然神经刺激显示这些传入神经在M细胞的远端侧树突上具有混合的电突触和突触能突触，但成对的突触前和突触后记录表明大多数个体连接是化学沉默的。为了确定编码的感觉信息以及这两种传输模式的相对贡献，在细胞内记录了M细胞对空气中声音刺激的反应。兴奋性突触后电位（EPSP）诱发的短100至900赫兹的“点”和较长的持续振幅和频率调制的声音占主导地位的快速，重复的EPSP叠加在一个潜在的缓慢去极化。快速EPSP 1）具有与突触前动作电位相当的动力学，2）在远端外侧树突上最大，3）对GluR拮抗剂不敏感。它们可能是耦合电位，功率谱分析表明它们构成了精确跟踪声音频率和振幅的高通信号。慢EPSP的空间分布表明近端和远端树突状来源，多房室模型的预测和AMPAR拮抗剂的影响，优先减少近端组件的结果支持。因此，第二类传入神经产生的一部分慢EPSP，与声音刺激，表明在LMCE突触的主要传输模式是电的。慢EPSP是刺激强度的动态低通表示。因此，在其他系统中分离的幅度和相位信息在M单元中被忠实地表示。
The teleost Mauthner (M-) cell mediates a sound-evoked escape behavior. A major component of the auditory input is transmitted by large myelinated club endings of the posterior VIIIth nerve. Paradoxically, although nerve stimulations revealed these afferents have mixed electrical and glutamatergic synapses on the M-cell's distal lateral dendrite, paired pre- and postsynaptic recordings indicated most individual connections are chemically silent. To determine the sensory information encoded and the relative contributions of these two transmission modes, M-cell responses to acoustic stimuli in air were recorded intracellularly. Excitatory postsynaptic potentials (EPSPs) evoked by both short 100- to 900-Hz “pips” and longer-lasting amplitude- and frequency-modulated sounds were dominated by fast, repetitive EPSPs superimposed on an underlying slow depolarization. Fast EPSPs1) have kinetics comparable to presynaptic action potentials,2) are maximal on the distal lateral dendrite, and3) are insensitive to GluR antagonists. They presumably are coupling potentials, and power spectral analysis indicated they constitute a high-pass signal that accurately tracks sound frequency and amplitude. The spatial profile of the slow EPSP suggests both proximal and distal dendritic sources, a result supported by predictions of a multicompartmental model and the effects of AMPAR antagonists, which preferentially reduced the proximal component. Thus a second class of afferents generates a portion of the slow EPSP that, with sound stimuli, demonstrate that the dominant mode of transmission at LMCE synapses is electrical. The slow EPSP is a dynamic, low-pass representation of stimulus strength. Accordingly, amplitude and phase information, which are segregated in other systems, are faithfully represented in the M-cell.