Suzuki Yoshinori, Morimoto Takako, Miyakawa Hiroyoshi, Aonishi Toru
Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan.
School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachio-ji, Tokyo, Japan.
PLoS One. 2014 Jan 23;9(1):e85790. doi: 10.1371/journal.pone.0085790. eCollection 2014.
How is binocular motion information integrated in the bilateral network of wide-field motion-sensitive neurons, called lobula plate tangential cells (LPTCs), in the visual system of flies? It is possible to construct an accurate model of this network because a complete picture of synaptic interactions has been experimentally identified. We investigated the cooperative behavior of the network of horizontal LPTCs underlying the integration of binocular motion information and the information representation in the bilateral LPTC network through numerical simulations on the network model. First, we qualitatively reproduced rotational motion-sensitive response of the H2 cell previously reported in vivo experiments and ascertained that it could be accounted for by the cooperative behavior of the bilateral network mainly via interhemispheric electrical coupling. We demonstrated that the response properties of single H1 and Hu cells, unlike H2 cells, are not influenced by motion stimuli in the contralateral visual hemi-field, but that the correlations between these cell activities are enhanced by the rotational motion stimulus. We next examined the whole population activity by performing principal component analysis (PCA) on the population activities of simulated LPTCs. We showed that the two orthogonal patterns of correlated population activities given by the first two principal components represent the rotational and translational motions, respectively, and similar to the H2 cell, rotational motion produces a stronger response in the network than does translational motion. Furthermore, we found that these population-coding properties are strongly influenced by the interhemispheric electrical coupling. Finally, to test the generality of our conclusions, we used a more simplified model and verified that the numerical results are not specific to the network model we constructed.
在果蝇视觉系统中，双目运动信息是如何在被称为小叶板切向细胞（LPTCs）的宽视野运动敏感神经元的双边网络中整合的？构建这个网络的精确模型是可能的，因为突触相互作用的完整图景已通过实验确定。我们通过对网络模型进行数值模拟，研究了水平LPTCs网络在双目运动信息整合以及双边LPTC网络中信息表征方面的协同行为。首先，我们定性地重现了先前在体内实验中报道的H2细胞的旋转运动敏感反应，并确定其主要可由双边网络的协同行为通过半球间电耦合来解释。我们证明，与H2细胞不同，单个H1和Hu细胞的反应特性不受对侧视觉半视野中运动刺激的影响，但这些细胞活动之间的相关性会因旋转运动刺激而增强。接下来，我们通过对模拟LPTCs的群体活动进行主成分分析（PCA）来检查整个群体活动。我们表明，前两个主成分给出的两种相关群体活动的正交模式分别代表旋转和平移运动，并且与H2细胞类似，旋转运动在网络中产生的反应比平移运动更强。此外，我们发现这些群体编码特性受到半球间电耦合的强烈影响。最后，为了检验我们结论的普遍性，我们使用了一个更简化的模型，并验证了数值结果并非特定于我们构建的网络模型。
