Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA.
Proc Natl Acad Sci U S A. 2012 Jun 26;109 Suppl 1(Suppl 1):10701-8. doi: 10.1073/pnas.1201885109. Epub 2012 Jun 20.
Star-nosed moles and tentacled snakes have exceptional mechanosensory systems that illustrate a number of general features of nervous system organization and evolution. Star-nosed moles use the star for active touch--rapidly scanning the environment with the nasal rays. The star has the densest concentration of mechanoreceptors described for any mammal, with a central tactile fovea magnified in anatomically visible neocortical modules. The somatosensory system parallels visual system organization, illustrating general features of high-resolution sensory representations. Star-nosed moles are the fastest mammalian foragers, able to identify and eat small prey in 120 ms. Optimal foraging theory suggests that the star evolved for profitably exploiting small invertebrates in a competitive wetland environment. The tentacled snake's facial appendages are superficially similar to the mole's nasal rays, but they have a very different function. These snakes are fully aquatic and use tentacles for passive detection of nearby fish. Trigeminal afferents respond to water movements and project tentacle information to the tectum in alignment with vision, illustrating a general theme for the integration of different sensory modalities. Tentacled snakes act as rare enemies, taking advantage of fish C-start escape responses by startling fish toward their strike--often aiming for the future location of escaping fish. By turning fish escapes to their advantage, snakes increase strike success and reduce handling time with head-first captures. The latter may, in turn, prevent snakes from becoming prey when feeding. Findings in these two unusual predators emphasize the importance of a multidisciplinary approach for understanding the evolution of brains and behavior.
星鼻鼹鼠和有触须的蛇拥有特殊的机械感觉系统，这展示了神经系统组织和进化的一些普遍特征。星鼻鼹鼠利用星状鼻进行主动触觉——快速扫描环境中的鼻射线。星鼻的机械感受器密度是所有哺乳动物中最高的，中央的触觉凹坑在解剖学上可见的新皮层模块中放大。感觉系统与视觉系统组织平行，展示了高分辨率感觉表示的普遍特征。星鼻鼹鼠是最快的哺乳动物觅食者，能够在 120 毫秒内识别和吃掉小猎物。最优觅食理论表明，星鼻是为了在竞争激烈的湿地环境中有效地利用小型无脊椎动物而进化的。有触须蛇的面部附属物表面上与鼹鼠的鼻射线相似，但它们的功能却截然不同。这些蛇完全水生，利用触须被动探测附近的鱼类。三叉神经传入神经对水的运动做出反应，并将触须信息投射到与视觉对齐的视丘中，展示了不同感觉模式整合的普遍主题。有触须的蛇作为罕见的敌人，利用鱼类的 C 型逃脱反应，将鱼类惊向它们的攻击方向——通常瞄准正在逃跑的鱼类的未来位置。通过将鱼类的逃脱转化为优势，蛇增加了攻击的成功率，并减少了用头捕获的处理时间。后者反过来可以防止蛇在进食时成为猎物。这两种不寻常的捕食者的发现强调了采用多学科方法来理解大脑和行为进化的重要性。
