Emotional impairment after right orbitofrontal lesion in a patient without cognitive deficits.

The present study describes a patient, M.L., with right orbitofrontal lesion, who showed no impairment on main neuropsychological tests, including those measuring frontal functions. Nevertheless, he had deeply affected emotional responses. In line with Damasio's work, the patient had lower skin conductance during the projection of a standardized set of emotional slides. Furthermore, he showed altered facial expressions to unpleasant emotions, displaying low corrugator supercilii electromyographical activity associated with reduced recall of unpleasant stimuli. During a task focusing on imagery of emotional situations, M.L.'s heart rate and skin conductance responses were affected during both pleasant and unpleasant conditions. Facial expressions to unpleasant imagery scripts were also impaired. Thus, the orbitofrontal cortex proved to play a critical role in retrieval of psychophysiological emotional patterns, particularly to unpleasant material. These results provide the first evidence that orbitofrontal lesions are associated with emotional impairment at several psychophysiological levels.