In the somatosensory system, hedonic information is coded by mechanoreceptors at the point of contact. Pleasure and pain signals travel along peripheral nerve pathways distinct from those for discriminative touch. Yet it remains unknown whether the central nervous system represents tactile hedonic information in sensory cortices as another dimension of exteroceptive information, similar to discriminative touch signals, or if tactile hedonic information is instantiated in regions mediating internal interoceptive states. Employing representational similarity analysis with a new approach of pattern component modeling, we decomposed multivoxel patterns to demonstrate that signals of painful but not pleasurable touch are represented in primary somatosensory cortices. By contrast, all hedonic touch representations were identified in regions associated with affect and interoception. This suggests that touch should be divided into external-exteroceptive and internal-interoceptive dimensions, with hedonic touch represented as an internal state, even though evoked by external stimulation.
bioRxiv Subject Collection: Neuroscience