Harley Cynthia M, Wagenaar Daniel A
Department of Entomology, University of Minnesota, St Paul, Minnesota, United States of America.
Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, United States of America.
PLoS One. 2014 Jan 21;9(1):e86120. doi: 10.1371/journal.pone.0086120. eCollection 2014.
While moving through their environment, medicinal leeches stop periodically and wave their head or body back and forth. This activity has been previously described as two separate behaviors: one called 'head movement' and another called 'body waving'. Here, we report that these behaviors exist on a continuum, and provide a detailed description of what we now call 'scanning'. Scanning-related behavior has been thought to be involved in orientation; its function has never before been assessed. While previous studies suggested an involvement of scanning in social behavior, or sucker placement, our behavioral studies indicate that scanning is involved in orienting the leech towards prey stimuli. When such stimuli are present, scanning behavior is used to re-orient the leech in the direction of a prey-like stimulus. Scanning, however, occurs whether or not prey is present, but in the presence of prey-like stimuli scanning becomes localized to the stimulus origin. Most likely, this behavior helps the leech to gain a more detailed picture of its prey target. The display of scanning, regardless of the presence or absence of prey stimuli, is suggestive of a behavior that is part of an internally driven motor program, which is not released by the presence of sensory stimuli. The data herein include first steps to understanding the neural mechanisms underlying this important behavior.
在其所处环境中移动时，医用水蛭会周期性地停下，并前后摆动头部或身体。这种活动此前被描述为两种不同的行为：一种称为“头部移动”，另一种称为“身体摆动”。在此，我们报告这些行为存在一个连续谱，并详细描述了我们现在所称的“扫描”。与扫描相关的行为一直被认为与定向有关；其功能此前从未被评估过。虽然之前的研究表明扫描与社会行为或吸盘放置有关，但我们的行为学研究表明，扫描参与使水蛭朝向猎物刺激定向。当存在此类刺激时，扫描行为用于使水蛭重新定向到类似猎物刺激的方向。然而，无论猎物是否存在，扫描都会发生，但在存在类似猎物刺激的情况下，扫描会局限于刺激源。很可能，这种行为有助于水蛭更详细地了解其猎物目标。无论是否存在猎物刺激，扫描的表现都表明这是一种由内部驱动的运动程序的一部分的行为，它不是由感觉刺激的存在所触发的。本文中的数据包括理解这一重要行为背后神经机制的初步步骤。
