Thermosensory micromapping of warm and cold sensitivity across glabrous and hairy skin of male and female hands and feet

Abstract

The ability of hands and feet to convey skin thermal sensations is an important contributor to our experience of the surrounding world. Surprisingly, the detailed topographical distribution of warm and cold thermosensitivity across hands and feet has not been mapped, although sensitivity maps exist for touch and pain. Using a recently developed quantitative sensory test, we mapped warm and cold thermosensitivity of 103 skin sites over glabrous and hairy skin of hands and feet in male (M; 30.2 ± 5.8 yr) and female (F; 27.7 ± 5.1 yr) adults matched for body surface area (M: 1.77 ± 0.2 m; F: 1.64 ± 0.1 m; P = 0.155). Findings indicated that warm and cold thermosensitivity varies by fivefold across glabrous and hairy skin of hands and feet and that hands (warm/cold sensitivity: 1.25/2.14 vote/°C) are twice as sensitive as the feet (warm/cold sensitivity: 0.51/0.99 vote/°C). Opposite to what is known for touch and pain sensitivity, we observed a characteristic distal-to-proximal increase in thermosensitivity over both hairy and glabrous skin (i.e., from fingers and toes to body of hands and feet), and found that hairy skin is more sensitive than glabrous. Finally, we show that body surface area-matched men and women presented small differences in thermosensitivity and that these differences are constrained to glabrous skin only. Our high-density thermosensory micromapping provides the most detailed thermosensitivity maps of hands and feet in young adults available to date. These maps offer a window into peripheral and central mechanisms of thermosensory integration in humans and will help guide future developments in smart skin and sensory neuroprostheses, in wearable, energy-efficient personal comfort systems, and in sport and protective clothing. NEW & NOTEWORTHY We provide the most detailed thermosensitivity maps across glabrous and hairy skin of hands and feet in men and women available to date. Our maps show that thermosensitivity varies by fivefold across hands and feet, distal regions (e.g., fingers, toes) are less sensitive than proximal (e.g., palm, sole), hands are twice as sensitive as feet, and men and women present small thermosensitivity differences. These findings will help guide developments in sensory neuroprostheses, wearable comfort systems, and sport/protective clothing.

Thermosensory mapping of skin wetness sensitivity across the body of young males and females at rest and following maximal incremental running

“…); yet sex differences in thermal sensitivity are often ambiguous (Stevens & Choo, ), and so it remains to be fully clarified whether sex has an independent physiological role in those difference (Filingeri et al . ).…”

“…In this respect, we have recently shown that BSA‐size matched males and females present limited differences in warm and cold sensitivity across their hands and feet (Filingeri et al . ). It could be speculated that the greater female cold (and wetness) sensitivity observed here is driven by the fact that our female group had a smaller BSA than males (Table ) and that this translated in a greater proportion of their skin being stimulated by the fixed size (1.32 cm 2 ) thermal probe used (Table ).…”

“…In accordance with previous studies (Filingeri et al . , , ), all participants were blinded to the nature and application of the stimuli to limit expectation biases, and they were only informed about the location of the stimulation. Furthermore, participants underwent a systematic familiarization and calibration to the testing procedures and perceptual scales prior to testing (Filingeri et al .…”

“…Furthermore, participants underwent a systematic familiarization and calibration to the testing procedures and perceptual scales prior to testing (Filingeri et al . , ). The same investigator performed all testing, to limit any inter‐individual variability arising from the procedures carried out.…”

“…; Filingeri et al . ) and present more sensitive thermal behaviours during exercise (Vargas et al . ), yet male and female skin wetness sensitivity has never been formally compared.…”