Active Touch: Vibrissal Tactile Discrimination in the Rat

我们知道，对触摸的敏感度在“被动”触摸和“主动”触摸之间是不同的，被动触摸是指物体仅仅接触到皮肤，而“主动”触摸是指物体通过移动触摸得到感觉。我们对这些差异背后的大脑机制知之甚少。该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。啮齿类动物积极地探索表面，使用它们的胡须阵列的特征“拂动”运动，称为面部触须。最近的研究表明，老鼠使用触须辨别纹理的能力非常出色，与灵长类动物使用指尖的能力相当，而且辨别纹理的行为策略也很相似。老鼠的须系统特别适合于研究，因为人们对它在解剖学上有序地投射到大脑有很多了解，而且因为须很容易进行无害的操作和观察。这个项目采用了一种新颖的方法，结合了动物训练、计算机辅助运动分析和单个神经细胞的电生理记录来研究这种主动触摸。比较了须接触、外周神经元活动和中枢皮质神经元活动之间的关系，并探讨了多须和感觉经验的作用。这项工作的结果将对躯体感觉神经科学以外的领域产生影响，以更好地理解动物如何使用主动驱动的感觉行为，感觉经验和学习如何增强辨别能力，以及更广泛地说，大脑如何获取和处理信息。

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.