ARE THERE SEPARATE ON AND OFF CHANNELS IN FLY MOTION VISION
ARE THERE SEPARATE ON AND OFF CHANNELS IN FLY MOTION VISION
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DOI：
10.1017/s0952523800009317
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发表时间：
1992-02-01
影响因子：
1.9
通讯作者：
BORST, A
中科院分区：
文献类型：
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作者：
EGELHAAF, M;BORST, A
视觉信息在一系列后续步骤中进行处理。这些步骤中的每个步骤的性能不仅取决于它本身执行的计算，而且还取决于它操作的视觉环境的表示。在这里，我们研究了信号预处理对苍蝇运动检测系统性能的影响。特别是，我们分析了视网膜输入信号是否经过整流并分离到单独的开和关通道，这些通道然后馈送独立的并行运动检测路径。我们记录了已识别的定向选择性中间神经元(H1细胞)对表观运动刺激的反应，即视野中两个相邻位置的连续亮度变化，以及仅在一个位置的亮度变化。对于明显的运动刺激，运动相关反应成分是通过从总体反应中减去单独呈现时对个别刺激成分的反应来确定的。可以得出以下结论：(1)由视野中两个位置亮度增加或降低的序列组成的表观运动具有相同的最佳刺激间时间间隔(图3)。(2)相同极性的亮度阶跃序列(递增或递减)分别在模仿细胞首选方向和零方向的运动时引起正和负的运动相关反应分量。当刺激序列的亮度阶跃具有不同的极性时，运动相关反应分量在符号中反转(图7)。(3)对亮度脉冲开始和结束的响应取决于脉冲持续时间。对于小于2的脉冲持续时间，S，两个事件相互作用(图9)。所有这些结果都没有提供任何迹象表明苍蝇在独立的开和关运动检测器中处理运动信息。两个标志的亮度变化更多地表示在相同运动检测器的输入端，并且由亮度增加和减少所产生的信号之间的交互考虑了它们的标志。视网膜输入的这种类型的预处理被认为可以使运动检测系统对噪声特别健壮。
Visual information is processed in a series of subsequent steps. The performance of each of these steps depends not only on the computations it performs itself but also on the representation of the visual surround on which it operates. Here we investigate the consequences of signal preprocessing for the performance of the motion-detection system of the fly. In particular, we analyze whether the retinal input signals are rectified and segregate into separate ON and OFF channels, which then feed independent parallel motion-detection pathways. We recorded the activity of an identified directionally selective interneuron (H1-cell) in response to apparent motion stimuli, i.e. sequential brightness changes at two neighboring locations in the visual field, as well as to brightness changes at only a single location. For apparent motion stimuli, the motion-dependent response component was determined by subtracting from the overall response the responses to the individual stimulus components when presented alone. The following conclusions could be derived: (1) Apparent motion consisting of a sequence of increased or decreased brightness at two locations in the visual field have the same optimum interstimulus time interval (Fig. 3). (2) Sequences of brightness steps of like polarity (either increments or decrements) elicit positive and negative motion-dependent response components when mimicking motion in the cell's preferred and null direction, respectively. The motion-dependent response components are inverted in sign when the brightness steps of a stimulus sequence have a different polarity (Fig. 7). (3) The responses to the beginning and the end of a brightness pulse depend on the pulse duration. For pulse durations of less than 2 s, both events interact with each other (Fig. 9). All of these results do not provide any indication that the fly processes motion information in independent ON and OFF motion detectors. Brightness changes of both signs are rather represented at the input of the same movement detectors, and interactions between signals resulting from both brightness increments and decrements take their sign into account. This type of preprocessing of the retinal input is argued to render a motion-detection system particularly robust against noise.