Targeting body representation distortions in anorexia nervosa through interoceptive conditioning

Bodily self-consciousness emerges from the integration of exteroceptive and interoceptive signals, which together shape the brain’s probabilistic representation of the body as “self.” Interpersonal Multisensory Stimulation (IMS) can induce embodiment illusions and modulate body representations. In anorexia nervosa (AN), characterized by impaired interoception and distorted body image, embodying an ideal, attractive underweight avatar induces the subjective experience of being thinner than usual. Conversely, embodying an undesired, unattractive normal-weight avatar increases overestimation of body size. Integrating interoceptive signals into IMS may enhance embodiment and promote recalibration of maladaptive body representations. In Study 1, healthy participants and AN patients underwent immersive virtual reality embodiment of underweight and normalweight avatars from a first-person perspective. Interoceptive signals were manipulated by providing visual feedback of the avatar’s breathing, either synchronous or asynchronous with participants’ real breathing, combined with synchronous or asynchronous visuo-tactile stimulation delivered to the legs, creating fully synchronous and asynchronous multisensory conditions. Embodiment strength (ownership, agency, location), body image distortion (Body Image Task, Body Schema Task, subjective body size feelings), affective responses (emotional valence, touch pleasantness), and avatar perception (self-similarity, attractiveness, implicit disgust, perceived weight comparison) were assessed. Synchronous IMS increased embodiment compared to asynchronous stimulation, regardless of avatar weight, and was associated with greater pleasantness and more positive emotional responses. Neurotypical participants embodied the normalweight avatar more strongly and rated it as more self-similar and attractive, whereas the underweight avatar was perceived as thinner than their actual body. Observing the underweight avatar from a first-person perspective led participants to select thinner avatars as resembling both their real and ideal bodies. In Study 2, an interoceptive-exteroceptive conditioning paradigm paired a normalweight avatar with asynchronous breathing and visuo-tactile IMS and immediately after an underweight avatar with synchronous breathing and visuo-tactile IMS, aiming to disrupt maladaptive associations between multisensory congruence and distorted body representations. Conditioning increased perceived similarity between the underweight avatar and the real body. Data collection and analysis in AN patients are ongoing. These findings suggest that interoceptive-exteroceptive integration may provide a mechanism to recalibrate distorted body representations, supporting the development of IMS-based interventions for AN and related disorders.