Skin-Mediated Interoception: The Perception of Affective Touch and Cutaneous Pain

Abstract

The last decades have seen an increasing focus on skin-mediated interoceptive modalities, such as tactile pleasantness and pain. For touch, this interest has been partially motivated by the discovery of a specialized group of skin afferents, C-tactile (CT) afferents that are found mainly in the hairy skin of the body and have been proposed as a supporting system for the detection of slow, caress-like touch, often referred to as affective touch. Similarly, there is growing interest in the affective and motivational dimensions of pain. Although painful and pleasant interoceptive sensations are associated predominantly with the skeletomuscular system, vascular system, and inner organs, the neural processing of affective touch and cutaneous pain starts in the skin. These modalities are homeostatically relevant since they provide information about physiological safety or threat. In this chapter, we first offer an overview of neuroanatomical, physiological, and functional evidence supporting the interoceptive nature of certain types of tactile stimuli, namely, tactile pleasantness and pain. We then describe the materials, methods, and procedure of experimental tasks focused on these modalities, which offer a promising avenue for the development of somatosensory methods to measure interoception.