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首页> 外文期刊>Journal of Neurophysiology >Functional circuitry for peripheral suppression in Mammalian Y-type retinal ganglion cells.
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Functional circuitry for peripheral suppression in Mammalian Y-type retinal ganglion cells.

机译：哺乳动物Y型视网膜神经节细胞外周抑制的功能电路。

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摘要

A retinal ganglion cell receptive field is made up of an excitatory center and an inhibitory surround. The surround has two components: one driven by horizontal cells at the first synaptic layer and one driven by amacrine cells at the second synaptic layer. Here we characterized how amacrine cells inhibit the center response of on- and off-center Y-type ganglion cells in the in vitro guinea pig retina. A high spatial frequency grating (4-5 cyc/mm), beyond the spatial resolution of horizontal cells, drifted in the ganglion cell receptive field periphery to stimulate amacrine cells. The peripheral grating suppressed the ganglion cell spiking response to a central spot. Suppression of spiking was strongest and observed most consistently in off cells. In intracellular recordings, the grating suppressed the subthreshold membrane potential in two ways: a reduced slope (gain) of the stimulus-response curve by approximately 20-30% and, in off cells, a tonic approximately 1-mV hyperpolarization. In voltage clamp, the grating increased an inhibitory conductance in all cells and simultaneously decreased an excitatory conductance in off cells. To determine whether center response inhibition was presynaptic or postsynaptic (shunting), we measured center response gain under voltage-clamp and current-clamp conditions. Under both conditions, the peripheral grating reduced center response gain similarly. This result suggests that reduced gain in the ganglion cell subthreshold center response reflects inhibition of presynaptic bipolar terminals. Thus amacrine cells suppressed ganglion cell center response gain primarily by inhibiting bipolar cell glutamate release.
机译：视网膜神经节细胞感受野由兴奋中心和抑制周围区域组成。周围有两个部分：一个由第一突触层的水平细胞驱动，另一个由第二突触层的无长突细胞驱动。在这里，我们表征了无长突细胞如何在体外豚鼠视网膜中抑制中心和偏心Y型神经节细胞的中心反应。超出水平细胞空间分辨率的高空间频率光栅（4-5 cyc / mm）漂移到神经节细胞接受野周围以刺激无长突细胞。外围光栅抑制了神经节细胞对中心点的尖峰响应。尖峰的抑制作用最强，在离体细胞中观察到的现象最一致。在细胞内记录中，光栅以两种方式抑制亚阈值膜电位：将刺激-响应曲线的斜率（增益）降低约20-30％，而在细胞外，则进行约1 mV的强直性超极化。在电压钳制中，光栅增加了所有细胞的抑制电导，同时降低了离细胞的兴奋性电导。为了确定中心反应抑制是突触前还是突触后（分流），我们在电压钳位和电流钳位条件下测量了中心响应增益。在两种情况下，外围光栅都类似地降低了中心响应增益。该结果表明，神经节细胞阈下中心反应的增益降低反映了突触前双极末端的抑制。因此无长突细胞主要通过抑制双极细胞谷氨酸的释放来抑制神经节细胞中心反应的获得。

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