Relationship-specific Encoding of Social Touch in Somatosensory and Insular Cortices

Humans use touch to maintain their social relationships, and the emotional qualities of depend on who touches whom. However, it is not known how affective dimensions are processed in brain. We measured haemodynamic brain activity with functional magnetic resonance imaging (fMRI) from 19 subjects (10 males), while they were touched upper thigh by either romantic partner, or an unfamiliar female male confederate saw hand one these individuals near but touched. used multi-voxel pattern analysis pre-defined regions interest reveal areas that encode a relationship-specific manner. The accuracy machine learning classifier identify actor for both feeling seeing exceeded chance level primary somatosensory cortex, insular cortex was above only condition. When classifying relationship (partner stranger), keeping toucher sex fixed, amygdala (AMYG), orbitofrontal (OFC), secondary cortices able discriminate significantly level. These results suggest information consistently across several regions. More complex about identity cortices, which can be considered early sensory areas.