Somatosensory coding in rodents has been mostly studied in the whisker system and hairy skin, whereas the function of low-threshold mechanoreceptors (LTMRs) in the rodent glabrous skin has received scant attention, unlike in primates where the glabrous skin has been the focus. The relative activation of different LTMR subtypes carries information about vibrotactile stimuli, as does the rate and temporal patterning of LTMR spikes. Rate coding depends on the probability of a spike occurring on each stimulus cycle (reliability), whereas temporal coding depends on the timing of spikes relative to the stimulus cycle (precision). Using in vivo extracellular recordings in male rats and mice of either sex, we measured the reliability and precision of LTMR responses to tactile stimuli including sustained pressure and vibration. Similar to other species, rodent LTMRs were separated into rapid-adapting (RA) or slow-adapting based on their response to sustained pressure. However, unlike the dichotomous frequency preference characteristic of RA1 and RA2/Pacinian afferents in other species, rodent RAs fell along a continuum. Fitting generalized linear models to experimental data reproduced the reliability and precision of rodent RAs. The resulting model parameters highlight key mechanistic differences across the RA spectrum; specifically, the integration window of different RAs transitions from wide to narrow as tuning preferences across the population move from low to high frequencies. Our results show that rodent RAs can support both rate and temporal coding, but their heterogeneity suggests that coactivation patterns play a greater role in population coding than for dichotomously tuned primate RAs.

啮齿动物的体感编码主要在胡须系统和毛状皮肤中进行研究，而啮齿动物无毛皮肤中的低阈值机械感受器 （LTMR） 的功能很少受到关注，这与无毛皮肤一直是重点的灵长类动物不同。不同 LTMR 亚型的相对激活携带有关振动触觉刺激的信息，LTMR 尖峰的速率和时间模式也是如此。速率编码取决于每个刺激周期上出现尖峰的概率（可靠性），而时间编码取决于相对于刺激周期的尖峰时间（精度）。使用雄性大鼠和任一性别的小鼠的体内细胞外记录，我们测量了 LTMR 对触觉刺激（包括持续压力和振动）反应的可靠性和精度。与其他物种类似，啮齿动物 LTMR 根据它们对持续压力的反应分为快速适应 （RA） 或慢适应。然而，与其他物种中 RA1 和 RA2/Pacinian 传入神经的二分频率偏好特征不同，啮齿动物 RA 呈连续体下降。将广义线性模型拟合到实验数据中，再现了啮齿动物 RAs 的可靠性和精密度。由此产生的模型参数突出了整个 RA 谱中的关键机制差异;具体来说，随着整个群体的优化偏好从低频变为高频，不同 RA 的集成窗口从宽到窄。我们的结果表明，啮齿动物 RAs 可以同时支持速率和时间编码，但它们的异质性表明，共激活模式在种群编码中的作用比二分调节的灵长类动物 RAs 更大。