Probing interoception via thermosensation: No specific relationships across multiple interoceptive sub-modalities

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.

Cardiac interoception is enhanced in blind individuals

“…It has also been proposed that blind individuals might rely more on internal hunger cues rather than taste in food choices (Gagnon, Kupers, & Ptito, 2013). Although it may suggest that the current findings could be generalizable, recent studies in sighted individuals have found that perceptual abilities on different interoceptive tasks that probe different submodalites are independent and uncorrelated (Garfinkel et al, 2016b; Ferentzi et al, 2018; Crucianelli, Enmalm, & Ehrsson, 2021) and that cardiac interoceptive accuracy does not correlate significantly with accuracy measures in skin-based interoceptive tasks (Crucianelli et al, 2021). Thus, to obtain a more complete picture of how visual deprivation affects interception, future studies should employ a battery of tests and investigate how different interoceptive submodalities are affected by visual deprivation and if some are more influenced than others.…”

Modeling tactile pleasantness across skin types at the individual level reveals a reliable and stable basic function

“…The study was conducted in accordance with the provisions of the Declaration of Helsinki 1975, as revised in 2008. Part of the data obtained in Experiment 1 was analyzed using a different statistical method for different purposes and has been published as part of another manuscript (Crucianelli, Enmalm & Ehrsson, 2021).…”

“…Consistent with the idea of affective touch as an interoceptive modality, our results showed that higher cardiac interoceptive accuracy as measured by means of a classic heartbeat counting task (Schandry, 1981) was related to a better fit of the negative quadratic model for the perception of touch on hairy skin (with a similar but non-significant statistical trend observed for non-hairy skin). In this regard, recent studies have reported non-significant relationships between the perception of affective touch and cardiac interoceptive accuracy (Crucianelli et al, 2018;Crucianelli, Enmalm & Ehrsson, 2021); however, interoceptive accuracy was a predictor of tactile pleasantness in a multisensory integration paradigm only when touch was delivered at the borderline velocity for CT optimality (9 cm/s, Crucianelli et al, 2018). Taken together, these findings suggest that the link between cardiac interoception and tactile pleasantness is more complex than originally thought, and modeling approaches might be better suited to describe such relationships.…”

Discrepancies in the Definition and Measurement of Interoception: A Comprehensive Discussion and Suggested Ways Forward

“…However, although we exclude the processing of signals through the external surface of the skin, we acknowledge that homeostatically-relevant external stimulations can induce internal signals (e.g., Crucianelli et al, 2021). Thermal and painful external stimuli, as well as affective touch, are all instances of external stimulations inducing internal physiological consequences or affect (Björnsdotter et al, 2010;Craig, 2008).…”