022-22 – Neural underpinnings of vicarious ratings of social touch in women at risk from eating disorders: A Transcranial Magnetic Stimulation (TMS) study

Anorexia Nervosa (AN) is an eating pathology characterized by restricted eating, body image distortions and an impaired social cognitive ability. Recent evidence suggests that altered responses to affective touch − a pleasant interoceptive stimulus involving activation of the C-Tactile (CT) system, may contribute to aetiology and maintenance of AN. Impairment of key neural networks involved in social perception and cognition such including the ventral medial Prefrontal Cortex (vmPFC) and the Somatosensory cortex (S1) might contribute towards atypical affective touch responses in AN. This current investigation aimed to establish whether inhibition of the right vmPFC and S1 is causative of atypical affective touch responses and reduced interoceptive accuracy associated with AN symptomatology. Self-report measures of interoceptive awareness and touch experiences were collected. Eighteen women received continuous theta burst TMS (cTBS) to right vmPFC, S1 and Vertex before providing third-party ratings of touch pleasantness delivered across 5 body sites (Cheek/back/ventral forearm/upper arm/palm) and 3 velocities (0cm/s, 5cm/s, 30cm/s) for two tasks (self-directed vs. other-directed touch). Findings revealed that vmPFC is casually involved in other- but not self-directed touch, as cTBS over this area significantly reduced pleasantness ratings for touch to another person compared to the Vertex and S1. On the other hand, cTBS over S1 led to a significant increase of pleasantness for touch to the self. Furthermore, this effect was positively associated to women’ levels of emotional awareness. Findings suggest that self vs. other-directed touch responses might depend on the involvement of key social networks in affective touch processing. Non-invasive brain stimulation interventions for AN should focus on improving the impairments in regions involved in social cognition.