Adaptation of response transients in fly motion vision. II: Model studies
Adaptation of response transients in fly motion vision. II: Model studies
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DOI：
10.1016/s0042-6989(03)00092-0
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发表时间：
2003-05-01
期刊：
影响因子：
1.8
通讯作者：
Haag, J
中科院分区：
文献类型：
--
作者：
Borst, A;Reisenman, C;Haag, J
所谓的“Reichardt检测器”可以成功地解释苍蝇运动视觉的许多特性。在其最简单的形式中，来自相邻图像位置的信号在低通滤波器延迟其中一个信号后相乘。该操作以镜像对称的形式进行两次，最终得到的输出信号被减去。正如这个模型所预测的那样，苍蝇的神经元对一个短暂的运动脉冲做出反应，活动突然增加，随后呈指数衰减。这种衰减的时间常数在提供适应性运动刺激后被证明缩短了。就检测器模型而言，这不可避免地意味着低通滤波器的时间常数是自适应的。考虑到这一点，人们可以预期稳态响应会随之向更高的速度转移，然而，这一点无法通过实验得到证实。在这里，我们展示了给定一个模型，在检测器的横臂上有一个额外的时间高通滤波器，只有高通滤波器决定脉冲响应的时间过程。因此，假设高通滤波器的时间常数是自适应轨迹，解决了上述冲突。此外，这种具有自适应时间常数的精细模型忠实地模拟了在苍蝇运动敏感神经元中观察到的瞬态响应振荡的特定对比依赖性。2003爱思唯尔科学有限公司版权所有。
The so-called 'Reichardt detector' can successfully account for many properties of fly motion vision. In its simplest form, the signals derived from neighboring image locations become multiplied after a low-pass filter has delayed one of them. This operation is done twice in a mirror-symmetrical form and the resulting output signals become finally subtracted. As predicted by this model, fly neurons respond to a brief motion pulse with a sudden rise in activity followed by an exponential decay. The time constant of this decay has been shown to shorten when tested after presentation of an adapting motion stimulus. In terms of the detector model this inevitably implies that the time constant of the low-pass filter is adapting. Given that, one would expect a concomitant shift of the steady-state response towards higher velocities, which, however, could not be experimentally verified. Here, we show that given a model with an additional temporal high-pass filter in the cross-arms of the detector, only the high-pass filter determines the time course of the impulse response. Assuming consequently that the time constant of the high-pass filter is the locus of adaptation resolves the conflicts mentioned above. Moreover, such an elaborated model with an adaptive time-constant faithfully mimics a particular contrast-dependency of transient response oscillations observed in fly motion sensitive neurons. (C) 2003 Elsevier Science Ltd. All rights reserved.