Retinal synaptic pathways underlying the response of the rabbit local edge detector.
Retinal synaptic pathways underlying the response of the rabbit local edge detector.
复制标题
兔子局部边缘检测器响应的视网膜突触通路。
DOI：
10.1152/jn.00987.2009
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发表时间：
2010
影响因子：
2.5
通讯作者：
Werblin,FrankS
中科院分区：
文献类型：
--
作者：
Russell,ThomasL;Werblin,FrankS
通过测量全细胞电压箝位下的兴奋和抑制电流的时空特性，研究了局部边缘检测器（LED）视网膜神经节细胞行为的电路机制。先前的研究表明，LED的激发受到周围活动的抑制。然而，外层和内部视网膜对这一特征的贡献以及所使用的神经递质目前尚不清楚。阻断视网膜抑制通路（GABAA、GABAC和甘氨酸）消除边缘选择性。条带尺寸为50 μm的反相光栅没有刺激水平细胞，但抑制了大约60%的donandoffexcitation，表明双极终端受到抑制（反馈抑制）。在药理学阻断方面，我们发现反馈抑制使用gabaa和gabac受体，但不使用甘氨酸。甘氨酸能抑制抑制gaba能反馈抑制在中心，使更大的兴奋电流响应亮度变化。激发、反馈抑制和直接（前馈）抑制对20- 50 μm宽度的亮度中性翻转光栅有响应，表明它们是由它们的接受域内的独立亚基驱动的，这赋予了对纹理和非纹理区域之间边界的敏感性。前馈抑制是甘氨酸能抑制，其上升时间比衰减时间快，并且在刺激开始时不起延迟尖峰的作用。在持续时间短至33毫秒的亮度变化中都可以触发正反相位，并且可以在已经产生高基线前馈抑制的场景中触发。我们的研究结果表明，LED电路如何利用亚感受野灵敏度，通过激发和反馈抑制之间的相互作用来检测视觉边缘，并通过产生前馈抑制来响应快速变化的场景中的快速亮度变化。
We studied the circuitry that underlies the behavior of the local edge detector (LED) retinal ganglion cell in rabbit by measuring the spatial and temporal properties of excitatory and inhibitory currents under whole cell voltage clamp. Previous work showed that LED excitation is suppressed by activity in the surround. However, the contributions of outer and inner retina to this characteristic and the neurotransmitters used are currently unknown. Blockage of retinal inhibitory pathways (GABAA, GABAC, and glycine) eliminated edge selectivity. Inverting gratings in the surround with 50-μm stripe sizes did not stimulate horizontal cells, but suppressedonandoffexcitation by roughly 60%, indicating inhibition of bipolar terminals (feedback inhibition). On pharmacologic blockage, we showed that feedback inhibition used both GABAAand GABACreceptors, but not glycine. Glycinergic inhibition suppressed GABAergic feedback inhibition in the center, enabling larger excitatory currents in response to luminance changes. Excitation, feedback inhibition, and direct (feedforward) inhibition responded to luminance-neutral flipping gratings of 20- to 50-μm widths, showing they are driven by independent subunits within their receptive fields, which confers sensitivity to borders between areas of texture and nontexture. Feedforward inhibition was glycinergic, its rise time was faster than decay time, and did not function to delay spiking at the onset of a stimulus. Both theonandoffphases could be triggered by luminance shifts as short in duration as 33 ms and could be triggered during scenes that already produced a high baseline level of feedforward inhibition. Our results show how LED circuitry can use subreceptive field sensitivity to detect visual edges via the interaction between excitation and feedback inhibition and also respond to rapid luminance shifts within a rapidly changing scene by producing feedforward inhibition.