Localised face processing by the human prefrontal cortex: stimulation-evoked hallucinations of faces.

Left and right prefrontal, premotor, and anterior temporal sites were stereotaxically implanted in order to direct surgical therapy for epilepsy. Direct electrical stimulation of the right anterior inferior frontal gyrus resulted in face-related hallucinations and illusions. When the patient was viewing a blank background, stimulation induced the experience of a rapid succession of faces. When the patient was viewing a real face, stimulation induced a series of modifications to that face. Effective stimulations induced afterdischarges that remained localised to right ventrolateral prefrontal cortex (VLPFC). Stimulation of other frontal and anterior temporal sites, bilaterally, induced no face-related hallucinations or illusions. This result supports a contribution of right VLPFC to face processing, and is consistent with models wherein it activates representations in working or declarative memories.