Abstract
Interoception, i.e., the perception of the physiological status of the body, includes signals originating both from inside the body and from its surface, the skin. Here, we focused on the perception of temperature, a crucial modality for the maintenance of homeostasis. We used a classic thermal detection task and developed a new thermal matching task, in which participants were asked to match a previously perceived moving thermal stimulus applied to their skin to a range of colder or warmer stimuli, presented in increasing or decreasing order. We investigated both hairy (forearm) and non-hairy (palm) skin to target the potential involvement of C-tactile fibres, which are part of an afferent homeostatic system found mainly on hairy skin. We also explored the relationship between performance on the two thermal tasks and on three other tasks in different interoceptive sub-modalities: cardiac perception, affective touch, and pain detection. We found a significantly more accurate perception of dynamic temperature on hairy skin compared to non-hairy skin overall, particularly when temperature was decreasing. Static perception of cooling was also superior on hairy skin and was related to dynamic temperature and pain only on non-hairy skin. Thus, thermosensation might offer a promising avenue to investigate interoception, and different mechanisms might be involved in the perception of affective thermal stimuli in hairy and non-hairy skin. Critically, we did not find any other significant relationship in objective perceptual performance among the interoceptive modalities, which suggests independent processing and that interoception might be best quantified using a battery of tests.
Competing Interest Statement
The authors have declared no competing interest.
