Mammals use glabrous (hairless) skin of their hands and feet to navigate and manipulate their environment. Cortical maps of the body surface across species contain disproportionately large numbers of neurons dedicated to glabrous skin sensation, in part reflecting a higher density of mechanoreceptors that innervate these skin regions. Here, we find that disproportionate representation of glabrous skin emerges over postnatal development at the first synapse between peripheral mechanoreceptors and their central targets in the brainstem. Mechanoreceptor synapses undergo developmental refinement that depends on proximity of their terminals to glabrous skin, such that those innervating glabrous skin make synaptic connections that expand their central representation. In mice incapable of sensing gentle touch, mechanoreceptors innervating glabrous skin still make more powerful synapses in the brainstem. We propose that the skin region a mechanoreceptor innervates controls the developmental refinement of its central synapses to shape the representation of touch in the brain.

哺乳动物使用手和脚的无毛（无毛）皮肤来导航和操纵它们的环境。不同物种的身体表面皮质图包含不成比例的大量专门用于无毛皮肤感觉的神经元，部分反映了支配这些皮肤区域的机械感受器的密度较高。在这里，我们发现在出生后发育过程中，外周机械感受器与其脑干中心目标之间的第一个突触处出现了不成比例的无毛皮肤。机械感受器突触经历发育细化，这取决于其末端与无毛皮肤的接近程度，使得那些支配无毛皮肤的突触连接扩大了它们的中心表征。在无法感知轻柔触摸的小鼠中，支配无毛皮肤的机械感受器仍然在脑干中产生更强大的突触。我们提出，机械感受器支配的皮肤区域控制其中央突触的发育细化，以塑造大脑中触觉的表征。