Direction Selectivity in Drosophila Emerges from Preferred-Direction Enhancement and Null-Direction Suppression
Direction Selectivity in Drosophila Emerges from Preferred-Direction Enhancement and Null-Direction Suppression
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DOI：
10.1523/jneurosci.1272-16.2016
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发表时间：
2016-08-03
影响因子：
5.3
通讯作者：
Clandinin, Thomas Robert
中科院分区：
文献类型：
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作者：
Leong, Jonathan Chit Sing;Esch, Jennifer Judson;Clandinin, Thomas Robert
在整个动物门类中，运动视觉依赖于神经元对以一个优先方向移动的刺激的优先反应，而不是相反的零方向。在果蝇的初级运动检测器中，方向选择性出现在两种神经元类型T4和T5中，但这种选择性背后的计算算法仍不清楚。我们发现T4和T5的感受野在时空上都表现出偏光和偏暗的子场，每个子场在时空上都是倾斜的。在线性-非线性模型框架中，T5感受野的时空组织预测了T5对运动刺激的反应。这些发现表明，方向选择性来自于对优先方向运动反应的增强，以及对零方向运动反应的抑制。因此，值得注意的是，T5结合了Hassenstein-Reichardt相关器和Barlow-Levick检测器使用的基本算法策略。我们的T5模型还为T5移动暗边缘的选择性提供了一个算法解释：我们的模型捕获了与这一刺激类别中的运动相关的所有两点和三点时空关联。更广泛地说，我们的发现揭示了输入路径视觉加工，特别是中心-周围，时间双相感受野，在T5中对方向选择性的产生的贡献。由于果蝇中T5的时空感受野对于脊椎动物视觉皮质中的简单细胞是常见的，我们的T5刺激反应模型将在实验容易处理的背景下提供信息，以确定更详细的、普遍计算的机械模型。
Across animal phyla, motion vision relies on neurons that respond preferentially to stimuli moving in one, preferred direction over the opposite, null direction. In the elementary motion detector of Drosophila, direction selectivity emerges in two neuron types, T4 and T5, but the computational algorithm underlying this selectivity remains unknown. We find that the receptive fields of both T4 and T5 exhibit spatiotemporally offset light-preferring and dark-preferring subfields, each obliquely oriented in spacetime. In a linear-nonlinear modeling framework, the spatiotemporal organization of the T5 receptive field predicts the activity of T5 in response to motion stimuli. These findings demonstrate that direction selectivity emerges from the enhancement of responses to motion in the preferred direction, as well as the suppression of responses to motion in the null direction. Thus, remarkably, T5 incorporates the essential algorithmic strategies used by the Hassenstein-Reichardt correlator and the Barlow-Levick detector. Our model for T5 also provides an algorithmic explanation for the selectivity of T5 for moving dark edges: our model captures all two-and three-point spacetime correlations relevant to motion in this stimulus class. More broadly, our findings reveal the contribution of input pathway visual processing, specifically center-surround, temporally biphasic receptive fields, to the generation of direction selectivity in T5. As the spatiotemporal receptive field of T5 in Drosophila is common to the simple cell in vertebrate visual cortex, our stimulus-response model of T5 will inform efforts in an experimentally tractable context to identify more detailed, mechanistic models of a prevalent computation.