Severson Kyle S, Xu Duo, Van de Loo Margaret, Bai Ling, Ginty David D, O'Connor Daniel H
Kavli Neuroscience Discovery Institute, Brain Science Institute, The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Neuroscience Training Program, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Kavli Neuroscience Discovery Institute, Brain Science Institute, The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Neuron. 2017 May 3;94(3):666-676.e9. doi: 10.1016/j.neuron.2017.03.045. Epub 2017 Apr 20.
Touch perception depends on integrating signals from multiple types of peripheral mechanoreceptors. Merkel-cell associated afferents are thought to play a major role in form perception by encoding surface features of touched objects. However, activity of Merkel afferents during active touch has not been directly measured. Here, we show that Merkel and unidentified slowly adapting afferents in the whisker system of behaving mice respond to both self-motion and active touch. Touch responses were dominated by sensitivity to bending moment (torque) at the base of the whisker and its rate of change and largely explained by a simple mechanical model. Self-motion responses encoded whisker position within a whisk cycle (phase), not absolute whisker angle, and arose from stresses reflecting whisker inertia and activity of specific muscles. Thus, Merkel afferents send to the brain multiplexed information about whisker position and surface features, suggesting that proprioception and touch converge at the earliest neural level.
触觉感知依赖于整合来自多种外周机械感受器的信号。 Merkel细胞相关传入神经被认为通过编码被触摸物体的表面特征在形状感知中起主要作用。然而，主动触摸过程中Merkel传入神经的活动尚未被直接测量。在这里，我们表明，行为小鼠的触须系统中的Merkel和未识别的慢适应性传入神经对自身运动和主动触摸都有反应。触摸反应主要由触须基部的弯矩（扭矩）及其变化率的敏感性决定，并且很大程度上可以由一个简单的力学模型来解释。自身运动反应编码触须周期（相位）内的触须位置，而不是绝对触须角度，并且源于反映触须惯性和特定肌肉活动的应力。因此，Merkel传入神经向大脑发送关于触须位置和表面特征的多路复用信息，这表明本体感觉和触觉在最早的神经水平上汇聚。
