In May of 2013, the final data was collected on a project in collaboration with India Morrison and Irene Perini, researchers at the University of Gothenburg. The project began in autumn 2011 and focused on a group of rare mutation carriers, most of whom live in Norrland.
Carriers of the mutation show reduced density in thinly-myelinated and unmyelinated sensory nerve fibers in the skin, which play crucial roles in signaling pain and touch information (Minde et al, Muscle Nerve, 2004). The Gothenburg team's project investigated the effects of the mutation on the structural and functional neuroanatomy of the brain. The thin-diameter sensory afferents affected by the mutation are associated primarily with pain, yet the carrier group's thermal pain thresholds did not differ from those of controls (Perini et al, in prep). This implies that their low density of fibers is sufficient for simple thermal detection. Any differences in cutaneous pain processing might lie elsewhere. The Gothenburg team's research asked whether this "elsewhere" might involve pain behavior - not in how one detects pain, but how one reacts to it. Part of the project therefore explored pain behavior using a task that requires using pain information in a behavioral context (Perini et al, J Neurosci, 2013). Another main part of the project investigated touch. Evidence is emerging that a particular type of thin-diameter sensory afferent, the tactile C or CT afferent, plays a role in affective touch. Affective touch is the loving, affectionate kind of touch you use with your family and close friends. Mutation carriers show an altered subjective evaluation of affective touch stimulation in the form of caressing (Morrison et al, Brain, 2011). A major aim of the project was therefore to chart the neuroanatomy of affective touch pathways in the carrier group. This research also explores the possibility that the carriers have a unique organization of sensory neural pathways in the brain - an organization that might also affect the way social, affective touch modulates stress responses.