Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden.
School of Medicine, Western Sydney University, Sydney, Australia.
Sci Rep. 2024 Nov 14;14(1):27943. doi: 10.1038/s41598-024-79693-5.
Among the various classes of fast-adapting (FA) tactile afferents found in hairy and glabrous skin, FA2 afferents, associated with Pacinian corpuscles (PC), preferentially signal high-frequency sinusoidal events corresponding with vibration percepts, in contrast to other classes associated with lower frequency flutter percepts. The FA2-PC complex is also uniquely sensitive to distant sources of vibration mechanically transmitted through anatomical structures. In the present study, we used a pulsatile waveform to assess the contribution of FA2 afferents to the perception of flutter-range frequency stimuli (~ 20 Hz) in combination with two methods to abolish local FA inputs and force a dependence on FA2 via transmission from adjacent structures. Firstly, we examined frequency discrimination and perception of vibration applied to the hairy skin overlying the ulnar styloid before and during the blockade of intradermal receptors by local anaesthesia. Secondly, we tested frequency discrimination on the digital glabrous skin before and during the blockade of myelinated fibres by ulnar nerve compression. Despite reliance on vibration transmission to activate remote PCs, we found that flutter-range frequency discrimination was unimpeded across both skin types. Comparisons with stimuli applied to the contralateral side also indicated that perceived frequency was unaffected. This confirms that flutter-range frequency perception can be encoded by the FA2-PC system. Our results demonstrate that input from receptors specialised for low-frequency signalling is not mandatory for flutter-range frequency perception. This explains how the constancy of frequency perception might be achieved across different skin regions, irrespective of the afferent type activated for transmitting these signals.
在毛发和无毛发皮肤中发现的各种快速适应（FA）触突类群中，FA2 触突与Pacinian 小体（PC）相关，优先传递与振动感知相对应的高频正弦事件，而其他与较低频率颤动感知相关的类群则不同。FA2-PC 复合体还对通过解剖结构机械传递的远距离振动源具有独特的敏感性。在本研究中，我们使用脉动波形来评估 FA2 传入神经对颤动范围频率刺激（~20 Hz）感知的贡献，同时使用两种方法来消除局部 FA 输入，并通过来自相邻结构的传输迫使依赖 FA2。首先，我们检查了在局部麻醉阻断皮内受体之前和期间施加于尺骨茎突上方的毛发皮肤的振动频率辨别和感知。其次，我们在尺神经压迫阻断有髓纤维之前和期间测试了数字无毛发皮肤的频率辨别。尽管依赖于振动传递来激活远程 PC，但我们发现颤动范围的频率辨别在两种皮肤类型中都不受阻碍。与施加于对侧的刺激进行比较也表明感知频率不受影响。这证实了颤动范围的频率感知可以通过 FA2-PC 系统进行编码。我们的结果表明，专门用于低频信号的受体的输入对于颤动范围的频率感知并非必需。这解释了频率感知的恒定性如何在不同的皮肤区域中实现，而与传递这些信号的传入类型无关。
