The transfer of signals from photoreceptor cells to large second-order neurones in the ocellar visual system of the locust Locusta migratoria
The transfer of signals from photoreceptor cells to large second-order neurones in the ocellar visual system of the locust Locusta migratoria
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蝗虫眼部视觉系统中感光细胞到大二级神经元的信号传递
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发表时间：
1995
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通讯作者：
Simmons
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作者：
Simmons
通过对光感受器和大的二阶 L-神经元进行同步细胞内记录，研究了蝗虫 Locusta migratoria 眼细胞通路中第一个突触的运作。 1. 突触的传递曲线是通过绘制两个细胞对彼此的光脉冲的初始峰值响应的幅度而获得的，表明 L-神经元对光感受器电位的变化极其敏感，并且该连接在黑暗中处于紧张活跃状态。 2. L-神经元中的突触后电流是从黑暗背景发出光脉冲时产生的，在比突触后电位稍亮的光强度下达到饱和。 3. 信噪比随着两个细胞中光强度的增加而提高，但是当信号从光感受器传输到 L-神经元时噪声的减少小于可能会聚在每个 L-神经元上的光感受器数量所预期的。 4. 在两个细胞中，在存在不同强度的背景照明的情况下，当曲线沿光强度轴移动时，强度响应曲线的斜率保持不变。适应相对较慢，因此，至少在背景照明增加后的几分钟内，两个细胞都保持持续的反应，并且对增加照明的刺激的反应幅度减小。在持续的背景照明期间，光感受器和 L-神经元之间的突触的传递曲线沿两个轴移动，但其最大斜率没有变化。 5. 突触传递曲线的斜率取决于光变化的速度和幅度。 6. 当向光感受器注入去极化电流脉冲时，L-神经元会产生短暂的超极化反应。反应的幅度取决于去极化刺激的强度和速度。 L 神经元做出初始响应后，后续响应的幅度会降低 200 毫秒。 7.当超极化恒定电流注入感光器时，L-神经元对感光器电刺激的反应幅度增加。
The operation of the first synapse in the ocellar pathway of the locust Locusta migratoria has been studied by making simultaneous intracellular recordings from photoreceptors and large, second-order L-neurones. 1. The transfer curve for the synapse, obtained by plotting the amplitudes of the initial peak responses by the two cells to pulses of light against each other, shows that L-neurones are extremely sensitive to changes in photoreceptor potential and that the connection is tonically active in darkness. 2. Postsynaptic current in an L-neurone, produced when pulses of light are delivered from a dark background, saturates at a slightly brighter light intensity than does the postsynaptic potential. 3. The signal-to-noise ratio improves with increases in light intensity in both cells, but the reduction in noise as signals are transmitted from photoreceptors to L-neurones is less than would be expected from the number of photoreceptors that probably converge on each L-neurone. 4. In both cells, in the presence of different intensities of background illumination, the slope of the intensityresponse curve is maintained as the curve moves along the light intensity axis. Adaptation is relatively slow so that, at least for several minutes after an increase in background illumination, both cells maintain a sustained response and the responses to stimuli of increased illumination are reduced in amplitude. During sustained background illumination, the transfer curve for the synapse between a photoreceptor and an L-neurone shifts along both axes without a change in its maximum slope. 5. The slope of the synaptic transfer curve depends on the speed as well as the amplitude of changes in light. 6. In response to injection of depolarising pulses of current into a photoreceptor, an L-neurone generates brief, hyperpolarising responses. The amplitude of the responses depends on the strength and speed of the depolarising stimuli. After an initial response by an L-neurone, subsequent responses are reduced in amplitude for 200 ms. 7. The amplitude of L-neurone responses to electrical stimulation of a photoreceptor increases when the hyperpolarising constant current is injected into the photoreceptor.