Lenting B P, Mastebroek H A, Zaagman W H
Vision Res. 1984;24(10):1341-7. doi: 10.1016/0042-6989(84)90189-5.
In the third optic lobe of the fly large-field spiking neurons are found which detect movement in a directionally selective way. For a wide variety of stimuli the responses of one of these, the H1 neuron, can very well be described and predicted by Reichardt's correlation model which is based on behavioural optomoter responses. However, when the spike rate is driven to large values with intense stimuli, the correlation model needs to be extended in order to account for the saturation phenomena that occur. Saturation can take place in all the elements of the large and extensive movement detecting system which contains interneurons in the optic lobes which process and guide the signals from the peripheral receptors to the central H1 neuron. To separate saturation at the peripheral site from that at the central level of the H1 neuron, a special stimulation technique was chosen. In measuring the saturation at the central level the stimulus parameter was the size of the stimulus field, while the modulation depth of the moving grating in this field stayed constant. Saturation at the peripheral site of the system was studied with a stimulus in which the modulation depth of the moving grating was the parameter and the size of the stimulus field was small and constant. When a simple feedback loop is incorporated in the final stage of the correlation model the saturation phenomena at the central level for steady-state stimulus conditions can very well be described. Saturation phenomena at the peripheral site of the system can also be explained by the same kind of feedback mechanisms in the input channels.
在果蝇的第三视叶中发现了大视野脉冲神经元，它们以方向选择性的方式检测运动。对于各种各样的刺激，其中一个名为H1神经元的反应可以很好地用基于行为视动反应的赖夏特相关模型来描述和预测。然而，当用强烈刺激使脉冲频率达到很高值时，相关模型需要扩展以解释所出现的饱和现象。饱和现象可能发生在大型且广泛的运动检测系统的所有元件中，该系统包含视叶中的中间神经元，这些中间神经元处理并将信号从外周感受器传导至中枢H1神经元。为了区分外周部位的饱和与H1神经元中枢水平的饱和，选择了一种特殊的刺激技术。在测量中枢水平的饱和时，刺激参数是刺激场的大小，而该场中移动光栅的调制深度保持恒定。系统外周部位的饱和是通过一种刺激来研究的，其中移动光栅的调制深度是参数，刺激场的大小小且恒定。当在相关模型的最后阶段纳入一个简单的反馈回路时，可以很好地描述稳态刺激条件下中枢水平的饱和现象。系统外周部位的饱和现象也可以用输入通道中相同类型的反馈机制来解释。
