Localised face processing by the human prefrontal cortex: Face-selective intracerebral potentials and post-lesion deficits

The patient described in the companion paper by Vignal, Chauvel, and Halgre n (this issue) was studied with event related potentials (ERPs) recorded di rectly within the brain substance, as well as with neuropsychological tests before and after therapeutic cortectomy. Large ERPs were evoked in the pre frontal cortex to faces, as compared to sensory controls and words. The lar gest such ERPs were highly localised to the same right anterior inferior pr efrontal site where direct electrical stimulation resulted in face hallucin ations. Face-selective ERPs were also evoked in the right prefrontal sites that had shown projected activity during face hallucinations, and near the right anterior superior temporal sulcus. Selective responses began about 15 0msec after face onset. Words, but not faces or sensory controls, evoked la rge ERPs in distinct locations, mainly in the left hemisphere. A successful surgical therapy was performed by removing the cortex surrounding the righ t prefrontal site where face-selective responses were recorded and where fa ce hallucinations were evoked by stimulation. This cortectomy resulted in a severe deficit in the recognition of emotional facial expressions, especia lly fear. No change was noted, however, in the recall of emotional words, o r other tasks. The current results provide strong support for the early, sp ecific, and sustained involvement of a multi-focal network in the right inf erior fronto-temporal cortex in face-processing.