Janus in thermosensation: the dual interoceptive-exteroceptive nature of thermal signals in body ownership

Thermosensation has traditionally been studied for its essential role in survival, enabling detection of environmental thermal stimuli and the maintenance of thermal homeostasis. Interestingly, unlike most sensory systems, thermosensation provides information about both the external world and the body's internal physiological state. In this review, we conceptualize these two dimensions as exteroceptive thermosensation, which conveys information about the thermal properties of external objects and the environment, and interoceptive thermosensation, which conveys information about the body's thermal state. Growing evidence suggests that this dual nature serves functions that extend beyond survival and homeostasis. Alterations in both thermal perception and thermoregulation have been associated with changes in body ownership, the experience that one's body belongs to oneself, while manipulations of thermal signals can influence ownership itself. Here, we review the physiological and neural bases of exteroceptive and interoceptive thermosensation, from peripheral encoding to central processing, and examine their relationship with body ownership in healthy and clinical populations. We discuss evidence suggesting partially distinct yet potentially convergent neural substrates for these two dimensions of thermosensation, highlighting the insular cortex and its broader connectivity network as a candidate through which thermal information may sustain body ownership. Finally, we consider how emerging neurotechnologies offer new opportunities to investigate the contribution of thermosensation to body ownership while also opening novel avenues for neurorehabilitation. We propose that thermosensation represents an underexplored contributor to body ownership, opening new avenues for future research on how bodily and environmental thermal signals are integrated to support the sense of self.