School of Mechanical, Aerospace and Systems Engineering, Division of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea.
J Exp Biol. 2011 May 1;214(Pt 9):1554-9. doi: 10.1242/jeb.052092.
When crawling on a solid surface, the nematode Caenorhabditis elegans (C. elegans) moves forward by propagating sinusoidal dorso-ventral retrograde contraction waves. A uniform propagating wave leads to motion that undulates about a straight line. When C. elegans turns as it forages or navigates its environment, it uses several different strategies of reorientation. These modes include the well-known omega turn, in which the worm makes a sharp angle turn forming an Ω-shape, and the reversal, in which the worm draws itself backwards. In these two modes of reorientation, C. elegans strongly disrupts its propagating sinusoidal wave, either in form or in direction, leading to abrupt directional change. However, a third mode of reorientation, the shallow turn, involves a gentler disruption of the locomotory gait. Analyzing the statistics of locomotion suggests that the shallow turn is by far the most frequent reorienting maneuver in navigation in the absence of food. We show that the worm executes a shallow turn by modulating the amplitude and wavelength of its curvature during forward movement, and provide a minimal description of the process using a three-parameter mathematical model. The results of our study augment the understanding of how these parameters are controlled at the neuromotor circuit level.
当线虫 Caenorhabditis elegans（秀丽隐杆线虫）在固体表面爬行时，它通过传播正弦形背腹向逆行收缩波向前移动。均匀传播的波导致波浪状的直线运动。当线虫在觅食或导航环境时，它会使用几种不同的重新定向策略。这些模式包括众所周知的ω 转弯，其中蠕虫形成一个 Ω 形的急转弯，以及反转，其中蠕虫向后拉自己。在这两种重新定向的模式中，线虫强烈地破坏其传播的正弦波，无论是在形式上还是在方向上，导致方向的突然变化。然而，第三种重新定向的模式，浅转弯，涉及到对运动步态的更温和的破坏。分析运动学的统计数据表明，在没有食物的情况下，浅转弯是迄今为止导航中最常见的重新定向操作。我们表明，线虫通过在向前运动时调节曲率的幅度和波长来执行浅转弯，并使用一个三参数数学模型提供了对该过程的最小描述。我们研究的结果增加了对线虫如何在神经运动电路水平上控制这些参数的理解。
