Warm pressure increases ventral striatum and mid-insula processing of social connection.

Social touch is an underappreciated regulatory behavior that contributes to social connection. Apart from previous research on gentle stroking, scant research has systematically addressed the influence of sensory inputs on social connection and their underlying neural mechanisms. Previous research spanning non-human animal and human findings suggest that warmer and deeper pressure touch-as found during hand-holding, hugging, and swaddling-may enhance affective experience. The current study, therefore, investigates how temperature, pressure, and social context alter affective experience and neural activity. During a functional MRI scan, 66 participants experienced warm or neutral temperature packs and deeper or lighter pressure weighted blankets as they viewed images of close others and strangers. Warmth and deeper pressure together, compared to either alone, led to the greatest activity in the ventral striatum (VS) and mid-insula (MI), regions previously implicated in salience and interoceptive processing, while viewing images of close others, but not strangers. Compared to warmth and deeper pressure, connectivity between the VS and MI was weaker during neutral temperature and lighter pressure, suggesting different coupling of these regions during warm pressure. Results suggest a novel sensory-affective pathway underlying the processes that support social connection.