Attentional cortical responses to enlarged faces are related to body fat in normal weight subjects: An electroencephalographic study

Abstract

Here we tested the hypothesis that in normal weight subjects, attentional cortical responses to the enlargement of faces are related to features of body weight, as a basis for future studies on the role of neurocognitive mechanisms in eating and weight disorders. Electroencephalographic data were recorded in 15 normal weight adults during a visual "oddball" paradigm. The subjects were given frequent (70%) and rare (30%) stimuli depicting faces (FACE), food (FOOD), and landscapes (CONTROL). The task was to click the mouse after the rare stimuli. These stimuli depicted the same frequent stimuli graphically dilated by 25% along the horizontal axis. Analysis of bioelectrical impedance indexed subjects' body fat percentage. Cortical attentional responses were probed by the difference between positive event-related potentials peaking around 200-600 ms post-stimulus for the frequent minus rare stimuli (P300). LORETA estimated P300 cortical sources. Main results showed that in the FACE condition, there was a negative correlation between the body fat percentage and the reaction time to the rare stimuli, and a positive correlation between the body fat percentage and the amplitude of prefrontal P300 sources (p<0.05). These results disclose a relationship between body fat and prefrontal attentional processes to body image in normal weight adults. The present study motivates future research testing the hypothesis that this relationship might be altered in patients with eating and weight disorders.