Emotional impairment after right orbitofrontal lesion in a patient withoutcognitive deficits

THE present study describes a patient, M.L., with right orbitofrontal lesio n, who showed no impairment on main neuropsychological tests, including tho se measuring frontal functions. Nevertheless, he had deeply affected emotio nal responses. In line with Damasio's work, the patient had lower skin cond uctance during the projection of a standardized set of emotional slides. Fu rthermore, he showed altered facial expressions to unpleasant emotions, dis playing low corrugator supercilii electromyographical activity associated w ith 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 expres sions to unpleasant imagery scripts were also impaired. Thus, the orbitofro ntal cortex proved to play a critical role in retrieval of psychophysiologi cal emotional patterns, particularly to unpleasant material. These results provide the first evidence that orbitofrontal lesions are associated with e motional impairment at several psychophysiological levels. NeuroReport 10:1 741-1746 (C) 1999 Lippincott Williams & Wilkins.