The impact of temperature and a chemesthetic cooling agent on lingual roughness sensitivity

The objective of the present study was to assess the influence of thermal sensations on lingual roughness sensitivity. Just-noticeable difference thresholds (JNDs) were determined using the staircase method for surface roughness from stainless steel coupons (Ra; 0.177-0.465 µm). Thresholds were assessed when cooling or heating the metal stimuli (n=32 subjects). Compared to the JND threshold obtained at an ambient stimulus temperature (21°C: 0.055±0.010μm), a cold (8°C) temperature significantly (p=0.019) reduced tongue sensitivity (i.e. increased JND) to surface roughness (0.109±0.016μm, respectively) whereas warm and hot temperatures had no significant effect (35°C: 0.084±0.012μm; 45°C: 0.081±0.011μm). To assess whether the effect of cooling on roughness thresholds is TRPM8-dependent, we collected roughness thresholds in a second cohort of subjects (n=27) following lingual application of the cooling compound Evercool 190 (24.3 µM). Interestingly, when Evercool 190 was used to elicit the cold sensation, lingual roughness JND's were unaffected compared to the control application of water (EC: 0.112±0.016μm; water: 0.102±0.017μm; p=0.604). That lingual roughness sensitivity is decreased by cold temperature, but not chemicals evoking cold sensations, suggests the mechanism underpinning thermal modulation is not TRPM8 dependent.PMID:38526180 | DOI:10.1093/chemse/bjae013
Source: Chemical Senses - Category: Biochemistry Authors: Source Type: research