Active Touch: Vibrissal Tactile Discrimination in the Rat

众所周知，当物体简单地接触皮肤时，对触摸的敏感度是不同的，而当物体通过移动的触摸感受到时，对触摸的敏感性是不同的。我们对这些差异背后的大脑机制知之甚少。这个项目利用了最近开发的一种新方法，使用啮齿动物的胡须作为模型系统。啮齿类动物通过其称为面部触须的胡须阵列的特有的“搅拌”运动来积极探索表面。最近的研究表明，老鼠用触须辨别纹理的能力很好，可以与灵长类动物用指尖辨别质地相媲美，而且分辨的行为策略也是相似的。老鼠的胡须系统特别适合研究，因为许多人都知道它优雅有序的解剖学投射到大脑，而且这些胡须很容易获得，进行无害的操作和观察。该项目使用动物训练、计算机辅助运动分析和单个神经细胞的电生理记录的新组合来研究这种主动触摸。比较了甩动接触、外周神经元活动和中枢皮层神经元活动之间的关系，并探讨了多个胡须和感觉经验的作用。这项工作的结果将超越躯体感觉神经科学，对更好地理解动物如何使用主动驱动的感觉行为，感官体验和学习如何增强辨别力，以及更广泛的大脑如何获取和处理信息产生影响。

Sensitivity to touch is known to be different between "passive" touch when an object simply touches the skin, and "active" touch when an object is felt by moving touch. We know very little about the mechanisms in the brain that underlie these differences. This project exploits a novel approach recently developed using rodent whiskers as a model system. Rodents actively explore surfaces using characteristic "whisking" movements of their array of whiskers called facial vibrissae. Recent work has shown that texture discrimination by rats using their vibrissae is excellent, comparable to primates using their fingertips, and that the behavioral strategies for discrimination are similar. The rat whisker system is particularly well-suited for study because a lot is known about its elegant anatomical orderly projection to the brain, and because the whiskers are easily accessible for harmless manipulation and observation. This project uses a novel combination of animal training, computer-assisted movement analysis, and electrophysiological recordings from single nerve cells to investigate this active touch. The relationship between whisking contact, activity in peripheral neurons and activity in central cortical neurons is compared, and the role of multiple whiskers and of sensory experience is explored. Results from this work will have an impact beyond somatosensory neuroscience toward better understanding how animals use actively driven sensory behavior in general, how sensory experience and learning enhance discrimination, and more generally how the brain acquires and processes information.