Human hairy skin contains a special type of nerve fibers, so-called CT-fibers that respond to slow stroking across the skin, such as a caress. Oxytocin, a hypothalamic nonapeptide, is released e.g. through light touch, caresses, warm temperature etc. Oxytocin release can be linked to well-being, stress reduction and other health-promoting effects. These anti-stress effects are particularly strong when oxytocin is released in response to low-intensity stimulation of the skin. In this project, we want to study the relationship between activation of CT-fibers and release/activation of the oxytocin system in response to light touch. Some genetic variations that have previously been linked to touch responses will also be studied.
Touch in social interactions is affective, yet the mechanisms by which touch modulates emotion and behavior remain unexplored.
The project´s guiding hypothesis is that neural pathways for affective touch mediate a calming effect via modulation of the parasympathetic branch of the human autonomic nervous system. The research will investigate brain responses using functional magnetic resonance imaging (fMRI), as well as measures of connectivity within brain networks. Particular focus is placed on the recently-discovered tactile C (CT) afferent. During a gentle caress, CTs discharge in patterns that correlate with touch pleasantness. The project also investigates the role of key neurotransmitters in humans, including endogenous oxytocin release during social touch. Relationships between these factors and genetic information will be tested by exploring variance in single nucleotide polymorphisms (SNPs).