Department of Molecular and Cell Biology, University of California, 385 LSA, Berkeley, CA, 94720-3200, USA.
Division of Biological Sciences, University of California San Diego, 3119 Pacific Hall, La Jolla, CA, 92093, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2019 Apr;205(2):191-202. doi: 10.1007/s00359-019-01317-5. Epub 2019 Feb 5.
Leeches in the wild are often found on smooth surfaces, such as vegetation, smooth rocks or human artifacts such as bottles and cans, thus exhibiting what appears to be a "substrate texture preference". Here, we have reproduced this behavior under controlled circumstances, by allowing leeches to step about freely on a range of silicon carbide substrates (sandpaper). To begin to understand the neural mechanisms underlying this texture preference behavior, we have determined relevant parameters of leech behavior both on uniform substrates of varying textures, and in a behavior choice paradigm in which the leech is confronted with a choice between rougher and smoother substrate textures at each step. We tested two non-exclusive mechanisms which could produce substrate texture preference: (1) a Differential Diffusion mechanism, in which a leech is more likely to stop moving on a smooth surface than on a rough one, and (2) a Smoothness Selection mechanism, in which a leech is more likely to attach its front sucker (prerequisite for taking a step) to a smooth surface than to a rough one. We propose that both mechanisms contribute to the texture preference exhibited by leeches.
野生蚂蟥通常在光滑的表面上被发现，例如植被、光滑的岩石或人类制品，如瓶子和罐子，因此表现出一种“基底纹理偏好”。在这里，我们通过让蚂蟥在一系列碳化硅基底（砂纸）上自由行走，在受控环境下再现了这种行为。为了开始理解这种纹理偏好行为的神经机制，我们已经确定了在均匀基底和具有不同纹理的基底上以及在行为选择范式中，蚂蟥在每一步面临更粗糙和更光滑基底纹理之间的选择时，蚂蟥行为的相关参数。我们测试了两种非排他性机制，这些机制可以产生基底纹理偏好：（1）差异扩散机制，在该机制中，蚂蟥更有可能在光滑表面上停止移动而不是在粗糙表面上停止移动，和（2）平滑性选择机制，在该机制中，蚂蟥更有可能将其前吸盘（前进的先决条件）附着在光滑表面上而不是粗糙表面上。我们提出，这两种机制都有助于蚂蟥表现出的纹理偏好。
