Grimes William N, Hoon Mrinalini, Briggman Kevin L, Wong Rachel O, Rieke Fred
Department of Physiology and Biophysics, Howard Hughes Medical Institute, University of Washington, Seattle, United States.
Department of Biological Structure, University of Washington, Seattle, United States.
Elife. 2014 Sep 1;3:e03892. doi: 10.7554/eLife.03892.
Cross-synaptic synchrony--correlations in transmitter release across output synapses of a single neuron--is a key determinant of how signal and noise traverse neural circuits. The anatomical connectivity between rod bipolar and A17 amacrine cells in the mammalian retina, specifically that neighboring A17s often receive input from many of the same rod bipolar cells, provides a rare technical opportunity to measure cross-synaptic synchrony under physiological conditions. This approach reveals that synchronization of rod bipolar cell synapses is near perfect in the dark and decreases with increasing light level. Strong synaptic synchronization in the dark minimizes intrinsic synaptic noise and allows rod bipolar cells to faithfully transmit upstream signal and noise to downstream neurons. Desynchronization in steady light lowers the sensitivity of the rod bipolar output to upstream voltage fluctuations. This work reveals how cross-synaptic synchrony shapes retinal responses to physiological light inputs and, more generally, signaling in complex neural networks.
跨突触同步——单个神经元输出突触间递质释放的相关性——是信号和噪声如何通过神经回路的关键决定因素。哺乳动物视网膜中视杆双极细胞与A17无长突细胞之间的解剖学连接，特别是相邻的A17细胞通常从许多相同的视杆双极细胞接收输入，这提供了一个罕见的技术机会来测量生理条件下的跨突触同步。这种方法表明，视杆双极细胞突触的同步在黑暗中近乎完美，并随着光照水平的增加而降低。黑暗中强烈的突触同步可将内在突触噪声降至最低，并使视杆双极细胞能够将上游信号和噪声忠实地传递给下游神经元。稳定光照下的去同步降低了视杆双极输出对上游电压波动的敏感性。这项工作揭示了跨突触同步如何塑造视网膜对生理光输入的反应，更普遍地说，揭示了复杂神经网络中的信号传递方式。
