Chen Xiao-Jun, Liu Yan-He, Xu Ning-Long, Sun Yan-Gang
Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.
Natl Sci Rev. 2021 Dec 3;9(6):nwab218. doi: 10.1093/nsr/nwab218. eCollection 2022 Jun.
Multiple cortical areas including the primary somatosensory cortex (S1) are activated during itch signal processing, yet cortical representation of itch perception remains unknown. Using novel miniature two-photon microscopic imaging in free-moving mice, we investigated the coding of itch perception in S1. We found that pharmacological inactivation of S1 abolished itch-induced scratching behavior, and the itch-induced scratching behavior could be well predicted by the activity of a fraction of layer 2/3 pyramidal neurons, suggesting that a subpopulation of S1 pyramidal neurons encoded itch perception, as indicated by immediate subsequent scratching behaviors. With a newly established optogenetics-based paradigm that allows precisely controlled pruritic stimulation, we found that a small fraction of S1 neurons exhibited an ignition-like pattern at the detection threshold of itch perception. Our study revealed the neural mechanism underlying itch perceptual coding in S1, thus paving the way for the study of cortical representation of itch perception at the single-neuron level in freely moving animals.
在瘙痒信号处理过程中，包括初级体感皮层（S1）在内的多个皮层区域会被激活，但瘙痒感知的皮层表征仍不清楚。我们利用新型微型双光子显微镜成像技术，在自由活动的小鼠中研究了S1中瘙痒感知的编码。我们发现，S1的药理学失活消除了瘙痒引起的抓挠行为，并且瘙痒引起的抓挠行为可以通过一部分第2/3层锥体神经元的活动得到很好的预测，这表明S1锥体神经元的一个亚群编码了瘙痒感知，这由随后立即出现的抓挠行为所表明。通过一种新建立的基于光遗传学的范式，该范式允许精确控制瘙痒刺激，我们发现一小部分S1神经元在瘙痒感知的检测阈值处表现出类似点火的模式。我们的研究揭示了S1中瘙痒感知编码的神经机制，从而为在自由活动动物的单神经元水平上研究瘙痒感知的皮层表征铺平了道路。
