Current models to explain how signals emanating from cutaneous mechanoreceptors generate representations of touch are based on comparisons of the tactile responses of mechanoreceptor subtypes and neurons in somatosensory cortex^{1,2,3,4,5,6,7,8}. Here we used mouse genetic manipulations to investigate the contributions of peripheral mechanoreceptor subtypes to cortical responses to touch. Cortical neurons exhibited remarkably homogeneous and transient responses to skin indentation that resembled rapidly adapting (RA) low-threshold mechanoreceptor (LTMR) responses. Concurrent disruption of signals from both Aβ RA-LTMRs and Aβ slowly adapting (SA)-LTMRs eliminated cortical responses to light indentation forces. However, disruption of either LTMR subtype alone caused opposite shifts in cortical sensitivity but otherwise largely unaltered tactile responses, indicating that both subtypes contribute to normal cortical responses. Selective optogenetic activation of single action potentials in Aβ RA-LTMRs or Aβ SA-LTMRs drove low-latency responses in most mechanically sensitive cortical neurons. Similarly, most somatosensory thalamic neurons were also driven by activation of Aβ RA-LTMRs or Aβ SA-LTMRs. These findings support a model in which signals from physiologically distinct mechanoreceptor subtypes are extensively integrated and transformed within the subcortical somatosensory system to generate cortical representations of touch.

目前解释皮肤机械感受器发出的信号如何产生触觉表征的模型是基于对机械感受器亚型和体感皮层神经元的触觉反应的比较^{1,2,3,4,5,6,7,8}. 在这里，我们使用小鼠基因操作来研究外周机械感受器亚型对皮质触摸反应的贡献。皮质神经元对皮肤压痕表现出非常均匀和瞬态的反应，类似于快速适应 (RA) 低阈值机械感受器 (LTMR) 反应。同时中断来自 Aβ RA-LTMR 和 Aβ 缓慢适应 (SA)-LTMR 的信号消除了皮质对光压痕力的反应。然而，单独破坏任一 LTMR 亚型会导致皮层敏感性发生相反的变化，但触觉反应在很大程度上没有改变，这表明这两种亚型都有助于正常的皮层反应。Aβ RA-LTMR 或 Aβ SA-LTMR 中单个动作电位的选择性光遗传学激活驱动了大多数机械敏感皮层神经元的低延迟反应。同样，大多数体感丘脑神经元也由 Aβ RA-LTMR 或 Aβ SA-LTMR 的激活驱动。这些发现支持一个模型，在该模型中，来自生理上不同的机械感受器亚型的信号在皮质下体感系统内广泛整合和转换，以产生皮质的触觉表征。