Gain control of synaptic transfer from second- to third-order neurons of cockroach ocelli.
Gain control of synaptic transfer from second- to third-order neurons of cockroach ocelli.
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从蟑螂Ocelli的二阶神经元转移突触转移。
DOI：
10.1085/jgp.107.1.121
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发表时间：
1996-01
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从第二至第三阶神经元的蟑螂ocelli的突触传递发生在一个指数上升的一部分，整个S形特征曲线相关的突触前和突触后电压。由于突触的非线性性质，二级神经元对光强度变化的线性响应是半波整流的，即，对光衰减的响应被放大，而对光增量的响应被压缩。在这里，我报告说，从第二至第三阶神经元的突触传递的增益的变化，由环境光水平和风刺激施加到尾索。通过同时细胞内记录二级和三级神经元来研究突触的传递特征。电位的变化引起的二级神经元的正弦调制光与各种平均亮度。随着平均亮度的降低，（a）二级神经元的平均膜电位被去极化，（B）二级和三级神经元之间的突触在指数特征曲线的较陡范围内工作，其中传递调制信号的增益较高，以及（c）三级神经元检测光衰减的增益增加。当风或触觉刺激施加到身体的各个部位，包括尾索时，二级神经元去极化。在风诱发的去极化，突触在一个陡峭的范围内的特征曲线，这导致了增加的增益的三阶神经元检测光递减。我的结论是，二阶和三阶神经元之间的突触的非线性性质提供了一个机会，调整增益传输信号的强度变化。类似的增益控制可能发生在其他视觉系统中，并成为更高级视觉功能的基础，即，运动的检测。
Synaptic transmission from second- to third-order neurons of cockroach ocelli occurs in an exponentially rising part of the overall sigmoidal characteristic curve relating pre- and postsynaptic voltage. Because of the nonlinear nature of the synapse, linear responses of second-order neurons to changes in ligh intensity are half-wave rectified, i.e., the response to a decrement in light is amplified whereas that to an increment in light is compressed. Here I report that the gain of synaptic transmission from second- to third-order neurons changes by ambient light levels and by wind stimulation applied to the cerci. Transfer characteristics of the synapse were studied by simultaneous intracellular recordings of second- and third-order neurons. Potential changes were evoked in second-order neurons by a sinusoidally modulated light with various mean luminances. With a decrease in the mean luminance (a) the mean membrane potential of second-order neurons was depolarized, (b) the synapse between the second- and third-order neurons operated in a steeper range of the exponential characteristic curve, where the gain to transmit modulatory signals was higher, and (c) the gain of third-order neurons to detect a decrement in light increased. Second-order neurons were depolarized when a wind or tactile stimulus was applied to various parts of the body including the cerci. During a wind-evoked depolarization, the synapse operated in a steeper range of the characteristic curve, which resulted in an increased gain of third-order neurons to detect light decrements. I conclude that the nonlinear nature of the synapse between the second- and third-order neurons provides an opportunity for an adjustment of gain to transmit signals of intensity change. The possibility that a similar gain control occurs in other visual systems and underlies a more advanced visual function, i.e., detection of motion, is discussed.