Mapping the Emotional Body

To address these questions, Walker and her colleagues asked participants to rate the pleasantness of static, slow, and fast touches as they viewed them being applied to the back, shoulder, forearm, or hand of a person on a video screen. As expected, slow touches to the back and shoulder were rated the most pleasant, while slow touches to the forearm were less so. In all three locations, participants rated slow touches as more pleasurable than fast or static touches. On the palm, however, where no CTs exist, slow strokes were not perceived as more pleasant than static touch.

The results, presented this week at SfN, suggest that people are empathetic towards such gentle touches and that, as in mice, CTs are differentially distributed throughout the body. Walker and her colleagues propose an emotional homunculus, analogous to the classical homunculus that depicts the amount of brain matter dedicated to processing signals from the body's discriminative touch neurons. Instead of big lips, hands, and feet, however, the emotional homunculus would have a big back and shoulders.

Understanding where CTs exist and how they function could inform how these nerve fibers help build and maintain social relationships, Walker said. Preterm babies, for example, benefit greatly from daily stroking, growing faster and showing reduced signs of stress. Conversely, lack of physical contact has been associated with poor outcomes in children at orphanages. It seems that “these CTs are providing that signal of safety and well-being,” Walker said.