Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA.
J Exp Biol. 2013 Dec 15;216(Pt 24):4530-41. doi: 10.1242/jeb.083477.
Animals can expend energy to acquire sensory information by emitting signals and/or moving sensory structures. We propose that the energy from locomotion itself could permit control of a sensor, whereby animals use the energy from movement to reconfigure a passive sensor. We investigated high-speed, antenna-mediated tactile navigation in the cockroach Periplaneta americana. We discovered that the passive antennal flagellum can assume two principal mechanical states, such that the tip is either projecting backward or forward. Using a combination of behavioral and robotic experiments, we demonstrate that a switch in the antenna's state is mediated via the passive interactions between the sensor and its environment, and this switch strongly influences wall-tracking control. When the tip of the antenna is projected backward, the animals maintain greater body-to-wall distance with fewer body collisions and less leg-wall contact than when the tip is projecting forward. We hypothesized that distally pointing mechanosensory hairs at the tip of the antenna mediate the switch in state by interlocking with asperities in the wall surface. To test this hypothesis, we performed laser ablation of chemo-mechanosensory hairs and added artificial hairs to a robotic antenna. In both the natural and artificial systems, the presence of hairs categorically increased an antenna's probability of switching state. Antennal hairs, once thought to only play a role in sensing, are sufficient for mechanically reconfiguring the state of the entire antenna when coupled with forward motion. We show that the synergy between antennal mechanics, locomotion and the environment simplifies tactile sensing.
动物可以通过发出信号和/或移动感觉结构来消耗能量来获取感觉信息。我们提出，运动本身的能量可以控制传感器，使动物能够利用运动能量重新配置被动传感器。我们研究了蟑螂美洲大蠊的高速天线介导触觉导航。我们发现，被动的触角鞭毛可以呈现两种主要的机械状态，使得尖端要么向后突出，要么向前突出。通过行为和机器人实验的组合，我们证明了天线状态的切换是通过传感器与其环境之间的被动相互作用介导的，并且这种切换强烈影响壁跟踪控制。当触角的尖端向后突出时，与尖端向前突出相比，动物保持更大的身体与墙壁之间的距离，身体碰撞和腿部与墙壁接触的次数更少。我们假设，触角尖端指向远侧的机械感觉毛通过与墙壁表面的突起互锁来介导状态切换。为了验证这一假设，我们对化学机械感觉毛进行了激光消融，并在机器人天线中添加了人工毛发。在自然和人工系统中，毛发的存在都显著增加了天线切换状态的概率。触角毛发曾经被认为只在感觉中起作用，但当与向前运动结合时，足以机械地重新配置整个天线的状态。我们表明，触角力学、运动和环境之间的协同作用简化了触觉感知。
