Premium
Warm hands, cold heart: progressive whole‐body cooling increases warm thermosensitivity of human hands and feet in a dose‐dependent fashion
Author(s) -
Filingeri Davide,
Morris Nathan B.,
Jay Ollie
Publication year - 2016
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/ep085955
Subject(s) - stimulus (psychology) , skin temperature , conditioning , thermoregulation , dorsum , inhibitory postsynaptic potential , receptive field , endogeny , audiology , psychology , medicine , neuroscience , anatomy , biomedical engineering , cognitive psychology , mathematics , statistics
New FindingsWhat is the central question of this study? Investigations on inhibitory/facilitatory modulation of vision, touch and pain show that conditioning stimuli outside the receptive field of testing stimuli modulate the central processing of visual, touch and painful stimuli. We asked whether contextual modulation also exists in human temperature integration.What is the main finding and its importance? Progressive decreases in whole‐body mean skin temperature (the conditioning stimulus) significantly increased local thermosensitivity to skin warming but not cooling (the testing stimuli) in a dose‐dependent fashion. In resembling the central mechanisms underlying endogenous analgesia, our findings point to the existence of an endogenous thermosensory system in humans that could modulate local skin thermal sensitivity to facilitate thermal behaviour.Although inhibitory/facilitatory central modulation of vision and pain has been investigated, contextual modulation of skin temperature integration has not been explored. Hence, we tested whether progressive decreases in whole‐body mean skin temperature ( T sk ; a large conditioning stimulus) alter the magnitude estimation of local warming and cooling stimuli applied to hairy and glabrous skin. On four separate occasions, eight men (27 ± 5 years old) underwent a 30 min whole‐body cooling protocol (water‐perfused suit; temperature, 5°C), during which a quantitative thermosensory test, consisting of reporting the perceived magnitude of warming and cooling stimuli (±8°C from 30°C baseline) applied to the hand (palm/dorsum) and foot (sole/dorsum), was performed before cooling and every 10 min thereafter. The cooling protocol resulted in large progressive reductions in T sk [10 min, −3.36°C (95% confidence interval −2.62 to −4.10); 20 min, −5.21°C (−4.47 to −5.95); and 30 min, −6.32°C (−5.58 to −7.05); P < 0.001], with minimal changes (∼0.08°C) in rectal temperature. While thermosensitivity to local skin cooling remained unchanged ( P = 0.831), sensitivity to skin warming increased significantly at each level of T sk for all skin regions [10 min, +4.9% (−1.1 to +11.0); 20 min, +6.1% (+0.1–12.2); and 30 min, +7.9% (+1.9–13.9); P = 0.009]. Linear regression indicated a 1.2% °C −1 increase in warm thermosensitivity with whole‐body skin cooling. Overall, large decreases in T sk significantly facilitated warm but not cold sensory processing of local thermal stimuli, in a dose‐dependent fashion. In highlighting a novel feature of human temperature integration, these findings point to the existence of an endogenous thermosensory system that could modulate local skin thermal sensitivity in relationship to whole‐body thermal states.