Response properties from turtle auditory hair cell afferent fibers suggest spike generation is driven by synchronized release both between and within synapses.
Response properties from turtle auditory hair cell afferent fibers suggest spike generation is driven by synchronized release both between and within synapses.
复制标题
海龟听觉毛细胞传入纤维的响应特性表明尖峰的产生是由突触之间和突触内的同步释放驱动的。
DOI：
10.1152/jn.00121.2013
复制
发表时间：
2013
影响因子：
2.5
通讯作者：
Ricci,AJ
中科院分区：
文献类型：
--
作者：
Schnee,ME;Castellano-Muñoz,M;Ricci,AJ
内耳毛细胞传入纤维突触能够长时间、高速率、高保真地传递信息。与其他感觉突触一样，毛细胞依赖于分级的受体电位和独特的囊泡运输和带状突触的释放特性来传递强度信息。从海龟听乳头的传入纤维的突触后记录确定兴奋性突触后电流（EPSC）是快速AMPA受体为基础的反应，具有快速的开始和衰减时间。EPSC的振幅变化为每根纤维1.15 ×，动力学表现出在较大振幅下减慢的趋势。复杂的EPSC是由单个事件的时间总和产生的，可能是跨突触的。复合EPSC比单一EPSC更有效地产生动作电位。钾诱发的释放增加EPSC的频率，特别是复杂的事件，但不增加EPSC的振幅。跨突触的EPSC的时间总和可能是这些突触处的动作电位产生的基础。宽振幅直方图探讨了多泡释放的机制，减少外部Ca 2+或引入Cd 2+或Sr 2+解偶联释放。结果是一致的，由突触囊泡大小的变化和协调释放这些囊泡的组合所产生的宽振幅直方图。据推测，多泡释放在多突触带状突触中的作用比在单突触传入纤维中的作用小。
Inner ear hair cell afferent fiber synapses are capable of transferring information at high rates for long periods of time with extraordinary fidelity. As at other sensory synapses, hair cells rely on graded receptor potentials and unique vesicle trafficking and release properties of ribbon synapses to relay intensity information. Postsynaptic recordings from afferent fibers of the turtle auditory papilla identified excitatory postsynaptic currents (EPSCs) that were fast AMPA receptor-based responses with rapid onset and decay times. EPSCs varied in amplitude by ∼15× per fiber, with kinetics that showed a tendency to slow at larger amplitudes. Complex EPSCs were produced by temporal summation of single events, likely across synapses. Complex EPSCs were more efficient at generating action potentials than single EPSCs. Potassium-evoked release increased the frequency of EPSCs, in particular complex events, but did not increase EPSC amplitudes. Temporal summation of EPSCs across synapses may underlie action potential generation at these synapses. Broad amplitude histograms were probed for mechanisms of multivesicular release with reduced external Ca2+or the introduction of Cd2+or Sr2+to uncouple release. The results are consistent with broad amplitude histograms being generated by a combination of the variability in synaptic vesicle size and coordinated release of these vesicles. It is posited that multivesicular release plays less of a role in multisynaptic ribbon synapses than in single synaptic afferent fibers.