Data from: Food vibrations: Asian spice sets lips trembling

Szechuan pepper, a widely used ingredient in the cuisine of many Asian countries, is known for the tingling sensation it induces on the tongue and lips. While the molecular mechanism by which Szechuan pepper activates tactile afferent fibres has been clarified, the tingling sensation itself has been less studied, and it remains unclear which fibres are responsible. We investigated the somatosensory perception of tingling in humans to identify the characteristic temporal frequency and compare this to the established selectivity of tactile afferents. Szechuan pepper was applied to the lower lip of participants. Participants judged the frequency of the tingling sensation on the lips by comparing this with the frequencies of mechanical vibrations applied to their right index finger. The perceived frequency of the tingling was consistently at around 50 Hz, corresponding to the range of tactile RA1 afferent fibres. Furthermore, adaptation of the RA1 channel by prolonged mechanical vibration reliably reduced the tingling frequency induced by Szechuan pepper, confirming that the frequency-specific tactile channel is shared between Szechuan pepper and mechanical vibration. Combining information about molecular reactions at peripheral receptors with quantitative psychophysical measurement may provide a unique method for characterizing unusual experiences by decomposing them into identifiable minimal units of sensation.

四川花椒（Szechuan pepper）是诸多亚洲国家料理中广泛使用的食材，其可使舌头与唇部产生麻刺感而闻名。尽管四川花椒激活触觉传入纤维（tactile afferent fibres）的分子机制已被阐明，但麻刺感本身的相关研究仍较为匮乏，且目前尚不清楚具体是哪一类纤维介导了该感受。本研究针对人类的麻刺感体感知觉展开探究，旨在明确其特征性时间频率，并将其与已明确的触觉传入纤维的选择性特征进行对比。研究人员将四川花椒施用于受试者的下唇，受试者通过将唇部感受到的麻刺感频率，与施加于右手食指的机械振动频率进行比对，以此判断该麻刺感的频率。结果显示，受试者感知到的麻刺感频率始终稳定在50 Hz左右，这一频率与RA1型触觉传入纤维（RA1 afferent fibres）的响应频率范围相匹配。此外，通过长时间机械振动使RA1通路产生适应后，四川花椒诱导的麻刺感频率显著降低，这证实了四川花椒与机械振动共享具有频率特异性的触觉通路。将外周受体的分子反应信息与定量心理物理测量相结合，或可提供一种独特的研究方法：通过将异常体感体验分解为可识别的最小感觉单元，实现对其特征的刻画。