Stable asymmetric interhemispheric theta power in patients with anorexia nervosa during haptic perception even after weight gain: a longitudinal study.

The aim of this study was to investigate the interhemispheric brain electrical asymmetries during a resting period and during haptic tasks in theta frequency band (4-8 Hz) between healthy controls (N = 10) and patients with anorexia nervosa (AN) (N = 10). Additionally, AN patients were investigated twice in a longitudinal design (T(0)-T(1)) to analyze treatment effects. At rest, a theta asymmetry was observed in the AN group during an acute stage of starvation (T(0)) but not after weight gain (T(1)). Importantly, theta asymmetry over central regions (C3-C4) was observed in the AN group during the acute stage of starvation (T(0) as well as after weight gain (T(1)) while performing haptic exploration task. In the control group, we found no significant theta asymmetry neither at rest nor during haptic explorations. Results are interpreted as an overarousal of the right hemisphere in AN patients during complex multisensory integration processing which is possibly a result of general functional deficits of the right hemisphere.