Deficits in haptic perception and right parietal theta power changes in patients with anorexia nervosa before and after weight gain.

OBJECTIVE: Our goal was to investigate whether patients with anorexia nervosa (AN) show deficits in haptic exploration tasks before and after weight gain.
METHOD: The haptic exploration tasks consisted of palpating the structure of six sunken reliefs in sequence with both hands, eyes closed. After each exploration, the structure was reproduced on a piece of paper. A 19-channel digital electroencephalogram (EEG; linked ears) was continuously recorded during rest and haptic tasks for 10 AN patients (females, mean age: 15.90) and 10 healthy controls (CO; females, mean age: 16.14). Mean spectral power density was calculated as the mean amplitude of the spectral lines of the theta band (4-8 Hz). The AN patients were examined again after weight gain (T(0) and T(1)).
RESULTS: The reproductions submitted by the AN patients were of notably poorer quality than those of the CO. Reproduction quality was unchanged after weight gain and independent of body mass index and intelligence. Mean exploration time was similiar in AN patients and CO. The analysis of spectral EEG power of both groups showed significant decrease in power data in the theta frequency band during haptic exploration compared with the rest intervals. The comparison of the theta power between CO and AN patients during haptic exploration showed major differences between the groups in both T(0) and T(1). Theta power was lower in AN patients than in the CO over the right hemisphere and right parietal regions. DISCUSSION: The quality of reproduction of the haptic stimuli and the theta-power changes indicate a cortical dysfunction and deficits in somatosensory integration processing of the right parietal cortex in AN patients even after weight gain. Copyright 2001 by John Wiley & Sons, Inc.