Functional properties of spontaneous excitatory currents and encoding of light/dark transitions in horizontal cells of the mouse retina
Functional properties of spontaneous excitatory currents and encoding of light/dark transitions in horizontal cells of the mouse retina
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DOI：
10.1111/ejn.13016
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发表时间：
2015-11-01
影响因子：
3.4
通讯作者：
Babai, Norbert
中科院分区：
文献类型：
--
作者：
Feigenspan, Andreas;Babai, Norbert
由于所有的视觉信息都表现在光感受器释放的递质的时空动态和二级神经元的突触后反应中，因此适当的突触传递函数对于视觉世界的有意义感知是至关重要的。水平细胞的功能贡献，以获得控制和组织的双极和神经节细胞感受野只能评估与信号处理水平细胞的深入了解。因此，建立了小鼠视网膜的水平切片制备，以记录来自水平细胞体的树突区完整并接收来自视锥光感受器的功能性突触输入。水平细胞体显示单相和更复杂的多峰波形的自发兴奋电流（spEPSC）。spEPSC由突触前锥体以3 pA的单位振幅的谷氨酸的量子释放诱导。非稳态噪声分析显示，spEPSC具有单指数衰减，由7-8个谷氨酸受体介导，单通道幅度为1.55pA。对明视全场照明的响应的特征在于强直内向电流或超极化的减少，spEPSCs的抑制，随后在光偏移时快速和瞬时内向电流。对不同频率周期性暗/光转换的响应取决于细胞的适应状态，其极限频率为10 Hz。光反应的开和关成分都由AMPA和红藻氨酸受体介导。水平细胞突触生理学的详细分析是理解光感受器带状突触的信号编码和处理的先决条件。
As all visual information is represented in the spatio-temporal dynamics of transmitter release from photoreceptors and the combined postsynaptic responses of second-order neurons, appropriate synaptic transfer functions are fundamental for a meaningful perception of the visual world. The functional contribution of horizontal cells to gain control and organization of bipolar and ganglion cell receptive fields can only be evaluated with an in-depth understanding of signal processing in horizontal cells. Therefore, a horizontal slice preparation of the mouse retina was established to record from horizontal cell bodies with their dendritic fields intact and receiving functional synaptic input from cone photoreceptors. Horizontal cell bodies showed spontaneous excitatory currents (spEPSCs) of monophasic and more complex multi-peak waveforms. spEPSCs were induced by quantal release of glutamate from presynaptic cones with a unitary amplitude of 3pA. Non-stationary noise analysis revealed that spEPSCs with a monoexponential decay were mediated by 7-8 glutamate receptors with a single-channel amplitude of 1.55pA. Responses to photopic full-field illumination were characterized by reduction of a tonic inward current or hyperpolarization, inhibition of spEPSCs, followed by a fast and transient inward current at light offset. The response to periodic dark/light transitions of different frequencies was dependent on the adaptational status of the cell with a limiting frequency of 10Hz. Both on and off components of the light response were mediated by AMPA and kainate receptors. Detailed analysis of horizontal cell synaptic physiology is a prerequisite for understanding signal coding and processing at the photoreceptor ribbon synapse.