Integration of celestial compass cues in the central complex of the locust brain
Integration of celestial compass cues in the central complex of the locust brain
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DOI：
10.1242/jeb.171207
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发表时间：
2018-01-01
影响因子：
2.8
通讯作者：
Homberg, Uwe
中科院分区：
文献类型：
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作者：
Pegel, Uta;Pfeiffer, Keram;Homberg, Uwe
许多昆虫依靠天文罗盘提示，如天空的偏振模式来确定空间方向。在沙漠蝗虫的中央复合体(CX)中，有多组神经元，对偏振光的振荡面敏感，因此可能起到内部偏振罗盘的作用。我们调查了其他天空罗盘信号，如阳光直射或天空的色度梯度是否可能对这个罗盘有贡献。我们记录了偏振敏感的Cx神经元，当一个未偏振的绿色或紫外线光点在动物头部周围移动时。对动物上方的偏振面(E矢量)敏感的所有类型的神经元也以方位依赖的方式对非偏振光点做出反应。对非偏振光点的调谐与波长无关，这表明神经元基于阳光直射而不是天空色度梯度来编码太阳方位。两种电池类型代表了太阳方位和天顶E矢量方向之间的自然90度关系，为太阳方位信息支持内部偏振罗盘提供了证据。大多数神经元对E矢量和非偏振光点的调谐取决于旋转方向，这与预期信号一致。反应的幅度及其变异性取决于背景放电的水平，可能表明不同的内部状态。偏振和太阳方位角信息的综合有力地表明，除了天空的偏振模式外，直射阳光可能是蝗虫天空罗盘导航的重要线索。
Many insects rely on celestial compass cues such as the polarization pattern of the sky for spatial orientation. In the desert locust, the central complex (CX) houses multiple sets of neurons, sensitive to the oscillation plane of polarized light and thus probably acts as an internal polarization compass. We investigated whether other sky compass cues like direct sunlight or the chromatic gradient of the sky might contribute to this compass. We recorded from polarizationsensitive CX neurons while an unpolarized green or ultraviolet light spot was moved around the head of the animal. All types of neuron that were sensitive to the plane of polarization (E-vector) above the animal also responded to the unpolarized light spots in an azimuthdependent way. The tuning to the unpolarized light spots was independent of wavelength, suggesting that the neurons encode solar azimuth based on direct sunlight and not on the sky chromatic gradient. Two cell types represented the natural 90 deg relationship between solar azimuth and zenithal E-vector orientation, providing evidence to suggest that solar azimuth information supports the internal polarization compass. Most neurons showed advances in their tuning to the E-vector and the unpolarized light spots dependent on rotation direction, consistent with anticipatory signaling. The amplitude of responses and its variability were dependent on the level of background firing, possibly indicating different internal states. The integration of polarization and solar azimuth information strongly suggests that besides the polarization pattern of the sky, direct sunlight might be an important cue for sky compass navigation in the locust.