The Role of the Skin in Interoception: A Neglected Organ?

Abstract

In the past 2 decades, interoception has received increasing attention in the fields of psychology and cognitive science, as well as neuroscience and physiology. A plethora of studies adopted the perception of cardiac signals as a proxy for interoception. However, recent findings have cast doubt on the methodological and intrinsic validity of the tasks used thus far. Therefore, there is an ongoing effort to improve the existing cardiac interoceptive tasks and to identify novel channels to target the perception of the physiological state of the body. Amid such scientific abundancy, one could question whether the field has been partially neglecting one of our widest organs in terms of dimensions and functions: the skin. According to some views grounded on anatomical and physiological evidence, skin-mediated signals such as affective touch, pain, and temperature have been redefined as interoceptive. However, there is no agreement in this regard. Here, we discuss some of the anatomical, physiological, and experimental arguments supporting the scientific study of interoception by means of skin-mediated signals. We argue that more attention should be paid to the skin as a sensory organ that monitors the bodily physiological state and further propose thermosensation as a particularly attractive model of skin-mediated interoception.

Keywords: body awareness; insula; interoception; skin; thermosensation.

Fig. 1.

Pathways from the skin to the brain.

Fig. 2.

Summary of the methods, results, and conclusions of the thermal matching task, fully described in Crucianelli et al. (2022). In line with classic approaches in the cardiac interoceptive field (e.g., Schandry, 1981), we applied a formula that allowed us to conveniently obtain a number between 0 and 1, where 0 indicates lower ability to detect changes from thermoneutrality (worst performance at the task) and 1 indicates higher such ability (better performance at the task). This index of thermal interoceptive ability can then be compared with similar indexes calculated for other interoceptive tasks in a “battery” of tests to probe different interoceptive submodalities.