Effects of emotional stimuli on event-related potentials and reaction times in orbitofrontal patients

We examined the effects of bilateral orbitofrontal damage on emotional processing and hemispheric attention capacity. Participants (four bilateral orbitofrontal patients and age-matched controls) discriminated between upright and inverted triangles (target). Targets were randomly presented in the left (LVF) or right visual hemifield (RVF, 150 ms). Emotional (pleasant or unpleasant; 150 ms) or neutral stimuli were presented centrally 350 ms prior to the target. Pleasant stimuli decreased whereas unpleasant stimuli increased RTs to LVF targets, with exaggerated effects in patients. Orbitofrontal damage differentially altered processing of emotional stimuli. In addition, orbitofrontal patients showed altered target ERPs, with evidence of increased activity over frontal sites for only LVF targets. The results suggest an interplay between orbitofrontal cortex and the right hemisphere.