谢菲尔德大学的T.Prescott教授带领他的研究团队,利用高速数码摄像仪与自动追踪系统,对老鼠如何前后左右快速移动胡须进行了研究。老鼠通过摆动胡须能够感知周围环境的变化,确定物体的位置、形状和材质,从而建立环境信息网络,以作出快速反应。研究团队通过将老鼠与其远亲有袋类(marsupial)进行对比后发现,可移动胡须的出现是爬行动物进化为哺乳动物道路上重要的、具有里程碑意义的变化。
当沿着直线行动时,老鼠前后摆动胡须的次数是相同的,当移动方向行动时,它们在转弯侧的胡须摆动更加迅速。当它们的头部某一边接触到物体时,另一边的胡须就开始加速运转以获取更多的信息,并对物体做出反应。
在最近的研究中,研究团队发现这些啮齿动物所使用的感观策略同样能够在南美一些小型有袋类中见到,比如家短尾负鼠(grey short-tailed opossum)。这种动物在地球上存在超过了1.25亿年,与早期哺乳类有诸多共同点,它们在进化树上早早便与啮齿类分枝了。这表明一些早期哺乳类也可能拥有能够摆动的胡须,可移动胡须的出现是哺乳动物进化的关键步骤。早期哺乳动物行夜间、树栖生活,因此,为了成功地在黑暗中生存,它们的感觉器官必定极为高效,包括视觉、听觉、嗅觉和触觉,可移动胡须的出现为它们提供了新型触觉感知方式,让它们在黑暗中生活更加便利。
除了继续研究啮齿类与有袋类之间的异同,研究团队还打算利用仿生学原理研制“长”有胡须的仿制机器人,这种机器人能在没有视觉的情况下导航,在灾难搜寻与营救方面必能大展身手。Tony说,可移动胡须与其他关键性状,比如温血、胎生、大脑容量等一样,是哺乳动物进化历程中的关键节点,虽然现代人类不再拥有它。(生物谷 Bioon.com)
doi:10.1098/rstb.2011.0156
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Active vibrissal sensing in rodents and marsupials
Ben Mitchinson, Robyn A. Grant, Kendra Arkley, Vladan Rankov, Igor Perkon and Tony J. Prescott
In rats, the long facial whiskers (mystacial macrovibrissae) are repetitively and rapidly swept back and forth during exploration in a behaviour known as ‘whisking’. In this paper, we summarize previous evidence from rats, and present new data for rat, mouse and the marsupial grey short-tailed opossum (Monodelphis domestica) showing that whisking in all three species is actively controlled both with respect to movement of the animal's body and relative to environmental structure. Using automatic whisker tracking, and Fourier analysis, we first show that the whisking motion of the mystacial vibrissae, in the horizontal plane, can be approximated as a blend of two sinusoids at the fundamental frequency (mean 8.5, 11.3 and 7.3 Hz in rat, mouse and opossum, respectively) and its second harmonic. The oscillation at the second harmonic is particularly strong in mouse (around 22 Hz) consistent with previous reports of fast whisking in that species. In all three species, we found evidence of asymmetric whisking during head turning and following unilateral object contacts consistent with active control of whisker movement. We propose that the presence of active vibrissal touch in both rodents and marsupials suggests that this behavioural capacity emerged at an early stage in the evolution of therian mammals.