Tactile stimulus discrimination in adolescents with anorexia nervosa: a behavioral and neurophysiological study.

Body image disturbance (BID) is a key symptom of anorexia nervosa (AN) and involves body size overestimation. Although this overestimation might be related to perceptual deficits, little is known about tactile perception in AN. To clarify the role of putative tactile deficits in BID, the present study investigated 36 adolescent female AN patients and 41 matched healthy controls (HC) using a tactile oddball paradigm during parallel EEG and MEG (EMEG) measurement. Tactile perception was behaviorally tested via the Touch Test (tactile perception threshold), a deviant count task, and a tactile stimulus discrimination task. Compared to HC participants, AN patients had similar tactile perception thresholds, but performance in the deviant count task and the tactile stimulus discrimination task was poor. Non-parametric cluster permutation tests on estimated neural source activity of evoked EMEG responses revealed that AN patients and HC did not differ regarding the neural differentiation between deviant and standard stimuli (oddball effect). However, estimated neural activity was globally reduced in the inferior temporal cortex and (by trend) in the posterior parietal cortex. These findings argue against the idea that behavioral discrimination deficits of tactile stimuli in AN are grounded in neural stimulus discrimination deficits. Instead, the overall reduced neural activity in the inferior temporal and posterior parietal cortex might reflect aberrant integration of neural tactile representations into a coherent multisensory body representation.