Temporal contrast adaptation in the input and output signals of salamander retinal ganglion cells
Temporal contrast adaptation in the input and output signals of salamander retinal ganglion cells
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DOI：
10.1523/jneurosci.21-01-00287.2001
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发表时间：
2001-01-01
影响因子：
5.3
通讯作者：
Rieke, F
中科院分区：
文献类型：
--
作者：
Kim, KJ;Rieke, F
我们研究了蝾螈视网膜神经节细胞的光诱发输入和输出信号如何适应时间对比度的变化，即，光强度在平均值附近的时间波动的深度的变化。增加时间对比度加速动力学，并降低了在神经节细胞索马和细胞的输出锋电位序列处测量的光诱发输入电流的灵敏度。对比度增加后，输入电流的灵敏度下降有两个不同的动力学成分，具有快速（10秒）的时间常数。对比度降低后的灵敏度恢复主要由具有中间（4-18秒）时间常数的单一组分决定。对比度适应ON和OFF细胞不同，OFF细胞的光诱发电流的动力学和幅度比ON细胞适应更强烈。然而，神经节细胞的输入电流中的对比度适应无法解释细胞的输出尖峰序列中的适应程度，这表明神经节细胞内在的机制起了作用。事实上，当波动的电流注入神经节细胞，尖峰产生的敏感性随着电流方差的增加而降低。药理学实验表明，适应穗代目前的变化是由于河豚毒素敏感的Na+通道的属性。
We investigated how the light-evoked input and output signals of salamander retinal ganglion cells adapt to changes in temporal contrast, i.e., changes in the depth of the temporal fluctuations in the light intensity about the mean. Increasing the temporal contrast sped the kinetics and reduced the sensitivity of both the light-evoked input currents measured at the ganglion cell soma and the output spike trains of the cell. The decline in sensitivity of the input currents after an increase in contrast had two distinct kinetic components with fast (10 sec) time constants. The recovery of sensitivity after a decrease in contrast was dominated by a single component with an intermediate (4-18 sec) time constant. Contrast adaptation differed for ON and OFF cells, with both the kinetics and amplitude of the light-evoked currents of OFF cells adapting more strongly than those of ON cells. Contrast adaptation in the input currents of a ganglion cell, however, was unable to account for the extent of adaptation in the output spike trains of the cell, indicating that mechanisms intrinsic to the ganglion cell contributed. Indeed, when fluctuating currents were injected into a ganglion cell, the sensitivity of spike generation decreased with increased current variance. Pharmacological experiments indicated that adaptation of spike generation to the current variance was attributable to properties of tetrodotoxin-sensitive Na+ channels.