Submitted Abstract
Individuals with anorexia nervosa (AN) overestimate their body size, i.e. body image distortion (BID). BID and its underlying mechanisms are not yet fully understood, although this would be crucial for improved interventions. The allocentric lock hypothesis posits that AN are locked in a negative body memory because of insufficient integration of exteroceptive and interoceptive information. Interoceptive deficits have been reported repeatedly in AN. Nevertheless, the integration of interoception and exteroception has not yet been examined sufficiently. The current project investigates cardio-visual integration (CVI) as a possible mechanism of BID in AN.Study 1 comprises the detailed investigation of mechanisms linking CVI to BID. Using virtual reality, participants will view a 3D image of their body, flashing in red in synchronicity to their heartbeat. We expect this cardio-visual full-body illusion (cFBI) to reduce BID. Moreover, we hypothesize for the effect of cFBI on BID to be mediated by enhanced cortical processing of cardio-afferent stimuli (heartbeat evoked potentials, HEPs).Studies 2 and 3 investigate CVI in patients with AN. Study 2 examines the relative importance of visceroception vs. CVI in BID. We expect that a task requiring CVI (“Whitehead task”) will explain variance in BID over and above a task relying merely on visceroception (“Schandry task”). Study 3 investigates the effect of cardiac feedback on the neurophysiological processing of body images in AN. We assume that presenting body images in synchrony with the participant’s heartbeat will have an effect on event-related potentials (ERPs) of the electroencephalogram (EEG), e.g. N170. This effect is expected to be weaker in AN, due to impaired CVI, and related to BID.Results will inform current theories of BID in AN with CVI as underlying mechanism. This will provide the basis for specifically targeting CVI in treatment and prevention, thus eventually improving the unsatisfactory outcome of current treatments.