Institute of Neuroinformatics, University of Zurich and ETH Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
J R Soc Interface. 2013 Jan 2;10(80):20121013. doi: 10.1098/rsif.2012.1013. Print 2013 Mar 6.
In many animals, rhythmic motor activity is governed by neural limit cycle oscillations under the control of sensory feedback. In the fruit fly Drosophila melanogaster, the wingbeat rhythm is generated myogenically by stretch-activated muscles and hence independently from direct neural input. In this study, we explored if generation and cycle-by-cycle control of Drosophila's wingbeat are functionally separated, or if the steering muscles instead couple into the myogenic rhythm as a weak forcing of a limit cycle oscillator. We behaviourally tested tethered flying flies for characteristic properties of limit cycle oscillators. To this end, we mechanically stimulated the fly's 'gyroscopic' organs, the halteres, and determined the phase relationship between the wing motion and stimulus. The flies synchronized with the stimulus for specific ranges of stimulus amplitude and frequency, revealing the characteristic Arnol'd tongues of a forced limit cycle oscillator. Rapid periodic modulation of the wingbeat frequency prior to locking demonstrates the involvement of the fast steering muscles in the observed control of the wingbeat frequency. We propose that the mechanical forcing of a myogenic limit cycle oscillator permits flies to avoid the comparatively slow control based on a neural central pattern generator.
在许多动物中，节奏性运动活动受神经极限环振荡的控制，受感觉反馈的调节。在果蝇 Drosophila melanogaster 中，翅膀的拍打节奏是由拉伸激活的肌肉产生的，因此独立于直接的神经输入。在这项研究中，我们探讨了果蝇的翅膀拍打运动的产生和周期性控制是否功能上是分离的，或者引导肌肉是否作为弱极限环振荡器的驱动力耦合到肌源性节律中。我们对系绳飞行的果蝇进行了行为测试，以检查其是否具有极限环振荡器的特征属性。为此，我们对果蝇的“陀螺”器官——平衡棒进行机械刺激，并确定翅膀运动和刺激之间的相位关系。当刺激的幅度和频率在特定范围内时，果蝇会与刺激同步，显示出强迫极限环振荡器的特征 Arnol'd 舌。在锁定之前，翅膀拍打频率的快速周期性调制证明了快速引导肌肉参与了观察到的翅膀拍打频率的控制。我们提出，肌源性极限环振荡器的机械强迫允许果蝇避免基于神经中枢模式发生器的相对较慢的控制。
